the geek computers

As a CCNA and/or CCNP candidate, you've got to be able to spot situations where Cisco router features can save your client money and time.  For example, if a spoke router is calling a hub router and the toll charges at the spoke site are higher than that of the hub router, having the hub router hang up initially and then call the spoke router back can save the client money (and make you look good!)

A popular method of doing this is using PPP callback, but as we all know, it's a good idea to know more than one way to do things in Cisco World!  A lesser-known but still effective method of callback is Caller ID Screening & Callback.  Before we look at the callback feature, though, we need to know what Caller ID Screening is in the first place!

This feature is often referred to simply as "Caller ID", which can be a little misleading if you've never seen this service in operation before. To most of us, Caller ID is a phone service that displays the source phone number of an incoming call.  Caller ID Screening has a different meaning, though.  Caller ID Screening on a Cisco router is really another kind of password - it defines the phone numbers that are allowed to call the router.

The list of acceptable source phone numbers is created with the isdn caller command.  Luckily for us, this command allows the use of x to specify a wildcard number.  The command isdn caller 555xxxx results in calls being accepted from any 7-digit phone number beginning with 555, and rejected in all other cases.  We'll configure R2 to do just that and then send a ping from R1 to R2.  To see the results of the Caller ID Screening, debug dialer will be run on R1 before sending the ping.  I’ve edited this output, since the output you see here will be repeated fire times – once for each ping packet.

R2(config-if)#isdn caller 555xxxx

R1#debug dialer

Dial on demand events debugging is on

R1#ping 172.12.12.2

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.12.12.2, timeout is 2 seconds:

03:30:25: BR0 DDR: Dialing cause ip (s=172.12.12.1, d=172.12.12.2)

03:30:25: BR0 DDR: Attempting to dial 8358662.

Success rate is 0 percent (0/5)


R1 doesn't give us any hints as to what the problem is, but we can see that the pings definitely aren't going through.  On R2, show dialer displays the number of screened calls.

R2#show dialer

BRI0 - dialer type = ISDN

Dial String      Successes   Failures    Last DNIS   Last status

8358661                  1          0    00:03:16       successful

7 incoming call(s) have been screened.

0 incoming call(s) rejected for callback.

The callback option mentioned in the last line shown above enables the router to reject a phone call, and then call that router back seconds later.

R2 will now be configured to initially hang up on R1, and then call R1 back.

R2(config-if)#isdn caller 8358661 callback

R1 will now ping R2.  The pings aren't returned, but seconds later R2 calls R1 back.

R1#ping 172.12.12.2

Success rate is 0 percent (0/5)

R1#

03:48:12: BRI0: wait for isdn carrier timeout, call id=0x8023

R1#

03:48:18: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up

R1#

03:48:18: BR0:1 DDR: dialer protocol up

R1#

03:48:19: %LINEPROTO-5-UPDOWN: Line protocol on Interface BRI0:1, changed state to up

R1#

03:48:24: %ISDN-6-CONNECT: Interface BRI0:1 is now connected to 8358662 R2

show dialer on R2 shows the reason for the call to R1 is a callback return call.

R2#show dialer

BRI0 - dialer type = ISDN

Dial String      Successes   Failures    Last DNIS   Last status

8358661                  3          0    00:00:48       successful

7 incoming call(s) have been screened.

10 incoming call(s) rejected for callback.

BRI0:1 - dialer type = ISDN

Idle timer (120 secs), Fast idle timer (20 secs)

Wait for carrier (30 secs), Re-enable (15 secs)

Dialer state is data link layer up

Dial reason: Callback return call

Time until disconnect 71 secs

Connected to 8358661 (R1)

The drawback to Caller ID Callback is that not all telco switches support it, so if you have the choice between this and PPP Callback, you're probably better off with PPP Callback.  However, it's always a good idea to know more than one way to get things done with Cisco!

More CCNA and CCNP candidates than ever before are putting together their own home labs, and there's no better way to learn about Cisco technologies than working with the real thing. Getting the routers and switches is just part of putting together a great CCNA / CCNP home lab, though. You've got to get the right cables to connect the devices, and this is an important part of your education as well. After all, without the right cables, client networks are going to have a hard time working!

For your Cisco home lab, one important cable is the DTE/DCE cable. These cables have two major uses in a home lab. To practice directly connecting Cisco routers via Serial interfaces (an important CCNA skill), you'll need to connect them with a DTE/DCE cable. Second, if you plan on having a Cisco router act as a frame relay switch in your lab, you'll need multiple DTE/DCE cables to do so. (Visit my website's Home Lab Help section for a sample Frame Relay switch configuration.)

If you have multiple switches in your lab, that's great, because you'll be able to get a lot of spanning tree protocol (STP) work in as well as creating Etherchannels. To connect your switches, you'll need crossover cables.

You'll need some straight-through cables as well to connect your routers to the switches.

Finally, if you're lucky enough to have an access server as part of your lab, you'll need an octal cable to connect your AS to the other routers and switches in your lab. The octal cable has one large connector on one end and eight numbered RJ-45 connectors on the other end. The large connector should be attached to the async port on your AS, and the numbered RJ-45 connectors will be connected to the console ports on your other routers and switches.

Choosing and connecting the right cables for your Cisco CCNA / CCNP home lab is a great learning experience, and it's also an important part of your Cisco education. After all, all great networks and home labs all begin at Layer One of the OSI model!

When you're studying for the CCNA and CCNP exams, you've got a lot of different choices when it comes to training.   One popular choice is choosing one of the many "boot camps" and five-day in-person courses that are out there.  I've taught quite a few of these, and while many of them are good, they do have drawbacks.

Of course, one is cost.  Many employers are putting the brakes on paying for CCNA and CCNP boot camps, and most candidates can't afford to pay thousands of dollars for such a class.  Then you've got travel costs, meals, and having to possibly burn your own vacation time to take the class.  Add in time away from your family and boot camps become impractical for many CCNA / CCNP candidates.

Another issue is fatigue.  I enjoy teaching week-long classes, but let's face facts - whether you're training for the CCNA or CCNP exams, you're going to get a lot of information thrown at you in just a few days.  You're going to be mentally and physically exhausted at the end of the week, and that's when some boot camps actually have you take the exam!  You've got to be refreshed and rested when you take the exam to have your best chance of success.

How can you get the benefit of an experienced instructor without paying thousands of dollars?  By taking a Video Boot Camp!  There are some high-quality computer-based training (CBT) courses out there, and these courses offer quite a few advantages for the CCNA and CCNP candidate.  These courses run hundreds instead of thousands of dollars, and you can train on your own schedule. It is important for you to make and keep that schedule, but instead of spending thousands of dollars and having to travel, you can get world-class CCNA and CCNP training in the comfort of your own home.

By combining a high-quality CCNA or CCNP CBT or video boot camp with a strong work ethic, you're on your way to passing the exam and accelerating your career.  Now get to work!

CCNA and CCNP candidates are well-versed in Spanning-Tree Protocol, and one of the great things about STP is that it works well with little or no additional configuration. There is one situation where STP works against us just a bit while it prevents switching loops, and that is the situation where two switches have multiple physical connections.

You would think that if you have two separate physical connections between two switches, twice as much data could be sent from one switch to the other than if there was only one connection. STP doesn't allow this by default, however in an effort to prevent switching loops from forming, one of the paths will be blocked.

SW1 and SW2 are connected via two separate physical connections, on ports fast0/11 and fast 0/12. As we can see here on SW1, only port 0/11 is actually forwarding traffic. STP has put the other port into blocking mode (BLK).


SW1#show spanning vlan 10


(some output removed for clarity)


Interface Role Sts Cost Prio.Nbr Type


Fa0/11    Root FWD 19 128.11 P2p

Fa0/12    Altn BLK 19 128.12 P2p


While STP is helping us by preventing switching loops, STP is also hurting us by preventing us from using a perfectly valid path between SW1 and SW2. We could literally double the bandwidth available between the two switches if we could use that path that is currently being blocked.

The secret to using the currently blocked path is configuring an Etherchannel. An Etherchannel is simply a logical bundling of 2 - 8 physical connections between two Cisco switches.

Configuring an Etherchannel is actually quite simple. Use the command "channel-group 1 mode on" on every port you want to be placed into the Etherchannel. Of course, this must be done on both switches if you configure an Etherchannel on one switch and don't do so on the correct ports on the other switch, the line protocol will go down and stay there.

The beauty of an Etherchannel is that STP sees the Etherchannel as one connection. If any of the physical connections inside the Etherchannel go down, STP does not see this, and STP will not recalculate. While traffic flow between the two switches will obviously be slowed, the delay in transmission caused by an STP recalculation is avoided. An Etherchannel also allows us to use multiple physical connections at one time.

Here's how to put these ports into an Etherchannel:

SW1#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW1(config)#interface fast 0/11

SW1(config-if)#channel-group 1 mode on

Creating a port-channel interface Port-channel 1


SW1(config-if)#interface fast 0/12

SW1(config-if)#channel-group 1 mode on



SW2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW2(config)#int fast 0/11

SW2(config-if)#channel-group 1 mode on

SW2(config-if)#int fast 0/12

SW2(config-if)#channel-group 1 mode on


The command "show interface trunk" and "show spanning-tree vlan 10" will be used to verify the Etherchannel configuration.


SW2#show interface trunk (some output removed for clarity)


Port Mode Encapsulation Status Native vlan

Po1 desirable 802.1q trunking 1


SW2#show spanning vlan 10 (some output removed for clarity)


Interface Role Sts Cost Prio.Nbr Type


Po1        Desg FWD 12    128.65 P2p


Before configuring the Etherchannel, we saw individual ports here. Now we see "Po1", which stands for the interface "port-channel1". This is the logical interface created when an Etherchannel is built. We are now using both physical paths between the two switches at one time!

That's one major benefit in action let's see another. Ordinarily, if the single open path between two trunking switches goes down, there is a significant delay while another valid path is opened - close to a minute in some situations. We will now shut down port 0/11 on SW2 and see the effect on the etherchannel.

SW2#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SW2(config)#int fast 0/11

SW2(config-if)#shutdown

3w0d: %LINK-5-CHANGED: Interface FastEthernet0/11, changed
state to administratively down


SW2#show spanning vlan 10


VLAN0010

Spanning tree enabled protocol ieee

Interface Role Sts Cost Prio.Nbr Type


Po1        Desg FWD 19    128.65 P2p



SW2#show interface trunk


Port Mode Encapsulation    Status    Native vlan


Po1 desirable 802.1q      trunking        1

The Etherchannel did not go down! STP sees the Etherchannel as a single link therefore, as far as STP is concerned, nothing happened.

Building an Etherchannel and knowing how it can benefit your network is an essential skill for CCNA and CCNP success, and it comes in very handy on the job as well. Make sure you are comfortable with building one before taking Cisco's exams!

OSPF is a major topic on both the CCNA and CCNP exams, and it's also the topic that requires the most attention to detail.  Where dynamic routing protocols such as RIP and IGRP have only one router type, a look at a Cisco routing table shows several different OSPF route types.






R1#show ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
In this tutorial, we'll take a look at the difference between two of these route types, E1 and E2.
Route redistribution is the process of taking routes learned via one routing protocol and injecting those routes into another routing domain.  (Static and connected routes can also be redistributed.)  When a router running OSPF takes routes learned by another routing protocol and makes them available to the other OSPF-enabled routers it's communicating with, that router becomes an Autonomous System Border Router (ASBR).
Let's work with an example where R1 is running both OSPF and RIP.  R4 is in the same OSPF domain as R1, and we want R4 to learn the routes that R1 is learning via RIP.  This means we have to perform route redistribution on the ASBR.  The routes that are being redistributed from RIP into OSPF will appear as E2 routes on R4:
R4#show ip route ospf

O E2    5.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0

     6.0.0.0/32 is subnetted, 1 subnets

O E2    6.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0

     172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks

O E2    172.12.21.0/30 [110/20] via 172.34.34.3, 00:33:32,
Ethernet0

O E2    7.1.1.1 [110/20] via 172.34.34.3, 00:33:21, Ethernet0

     15.0.0.0/24 is subnetted, 1 subnets

O E2    15.1.1.0 [110/20] via 172.34.34.3, 00:33:32, Ethernet0

E2 is the default route type for routes learned via redistribution.  The key with E2 routes is that the cost of these routes reflects only the cost of the path from the ASBR to the final destination; the cost of the path from R4 to R1 is not reflected in this cost.  (Remember that OSPF's metric for a path is referred to as "cost".)
In this example, we want the cost of the routes to reflect the entire path, not just the path between the ASBR and the destination network.  To do so, the routes must be redistributed into OSPF as E1 routes on the ASBR, as shown here.
R1#conf t

Enter configuration commands, one per line.  End with CNTL/Z.

R1(config)#router ospf 1

R1(config-router)#redistribute rip subnets metric-type 1

Now on R4, the routes appear as E1 routes and have a larger metric, since the entire path cost is now reflected in the routing table.
O E1    5.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0

     6.0.0.0/32 is subnetted, 1 subnets

O E1   6.1.1.1 [110/100] via 172.34.34.3, 00:33:21, Ethernet0

     172.12.0.0/16 is variably subnetted, 2 subnets, 2 masks

O E1    172.12.21.0/30 [110/94] via 172.34.34.3, 00:33:32, Ethernet0

O E1    7.1.1.1 [110/94] via 172.34.34.3, 00:33:21, Ethernet0

     15.0.0.0/24 is subnetted, 1 subnets

O E1    15.1.1.0 [110/94] via 172.34.34.3, 00:33:32, Ethernet0

Knowing the difference between E1 and E2 routes is vital for CCNP exam success, as well as fully understanding a production router's routing table.   Good luck in your studies!

BGP is one of the most complex topics you'll study when pursuing your CCNP, if not the most complex. I know from personal experience that when I was earning my CCNP, BGP is the topic that gave me the most trouble at first. One thing I keep reminding today's CCNP candidates about, though, is that no Cisco technology is impossible to understand if you just break it down and understand the basics before you start trying to understand the more complex configurations.

BGP attributes are one such topic. You've got well-known mandatory, well-known discretionary, transitive, and non-transitive. Then you've got each individual BGP attribute to remember, and the order in which BGP considers attributes, and what attributes even are... and a lot more! As with any other Cisco topic, we have to walk before we can run. Let's take a look at what attributes are and what they do in BGP.

BGP attributes are much like what metrics are to OSPF, RIP, IGRP, and EIGRP. You won't see them listed in a routing table, but attributes are what BGP considers when choosing the best path to a destination when multiple valid (loop-free) paths exist.

When BGP has to decide between such paths, there is an order in which BGP considers the path attributes. For success on the CCNP exams, you need to know this order. BGP looks at path attributes in this order:

Highest weight (Cisco-proprietary BGP value)

Highest local preference (LOCAL_PREF)

Prefer locally originated route.

Shortest AS_PATH is preferred.

Choose route with lowest origin code. Internal paths are preferred over external paths, and external paths are preferred over paths with an origin of "incomplete".
Lowest multi-exit discriminator (MED)

External BGP routes preferred over Internal BGP routes.

If no external route, select path with lowest IGP cost to the next-hop router for iBGP.

Choose most recent route.

Choose lowest BGP RID (Router ID).

If you don't know what these values are, or how they're configured, don't panic! The next several parts of this BGP tutorial will explain it all. So spend some time studying this order, and in part II of this free BGP tutorial, we'll look at each of these values in detail. Keep studying!

To earn your CCNA or CCNP certification, you've got to understand the basics of trunking.  This isn't just a CCNA topic - you must have an advanced understanding of trunking and etherchannels to pass the BCMSN exam and earn your CCNP as well.  Before we address those advanced topics, though, you need to master the fundamentals!

A trunk allows inter-VLAN traffic to flow between directly connected switches.  By default, a trunk port is a member of all VLANs, so traffic for any and all VLANs can travel across this trunk.  That includes broadcast traffic!

The default mode of a switch port does differ between models, so always check your documentation.  On Cisco 2950 switches, every single port is in dynamic desirable mode by default, meaning that every port is actively attempting to trunk.  On these switches, the only action needed from us is to physically connect them with a crossover cable. In just a few seconds, the port light turns green and the trunk is up and running.  The command show interface trunk will verify trunking.

How does the receiving switch know what VLAN the frame belongs to?  The frames are tagged by the transmitting switch with a VLAN ID, reflecting the number of the VLAN whose member ports should receive this frame.  When the frame arrives at the remote switch, that switch will examine this ID and then forward the frame appropriately.

There are two major trunking protocols you must understand and compare successfully, those being ISL and IEEE 802.1Q.  Let's take a look at the details of ISL first.


ISL is a Cisco-proprietary trunking protocol, making it unsuitable for a multivendor environment.  That's one drawback, but there are others.  ISL will place both a header and trailer onto the frame, encapsulating it.  This increases the overhead on the trunk line.

You know that the default VLAN is also known as the "native VLAN", and another drawback to ISL is that ISL does not use the concept of the native VLAN.  This means that every single frame transmitted across the trunk will be encapsulated.

The 26-byte header that is added to the frame by ISL contains the VLAN ID; the 4-byte trailer contains a Cyclical Redundancy Check (CRC) value.  The CRC is a frame validity scheme that checks the frame's integrity.

In turn, this encapsulation leads to another potential issue.  ISL encapsulation adds 30 bytes total to the size of the frame, potentially making them too large for the switch to handle.  (The maximum size for an Ethernet frame is 1518 bytes.)

IEEE 802.1q differs substantially from ISL.  In contrast to ISL, dot1q does not encapsulate frames.  A 4-byte header is added to the frame, resulting in less overhead than ISL.  If the frame is destined for hosts residing in the native VLAN, that header isn't added.  Since the header is only 4 bytes in size, and isn't even placed on every frame, using dot1q lessens the chance of oversized frames. When the remote port receives an untagged frame, the switch knows that these untagged frames are destined for the native VLAN.

Knowing the details is the difference between passing and failing your CCNA and CCNP exams.  Keep studying, get some hands-on practice, and you’re on your way to Cisco certification success!

To pass the Cisco CCNA and CCNP certification exams, as well as becoming a world-class networker, you've got to know how and when to use floating static routes. And if you're wondering what makes them "float" -- read on!


In this example, R1 and R2 are running OSPF over a Frame Relay network, 172.12.123.0 /24. They're also connected by a BRI ISDN link, 172.12.12.0 /24. R1 is advertising a loopback network, 1.1.1.1 /32, via OSPF. We want R2 to have a route to that loopback even if the frame goes down - and here, we'll use a floating static route to make that happen.

R2 sees the route to the loopback interface via OSPF, and can ping that interface successfully.

R2#show ip route ospf

1.0.0.0/32 is subnetted, 1 subnets

O 1.1.1.1 [110/65] via 172.12.123.1, 00:00:02, Serial0


R2#ping 1.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 68/68/68 ms

This is when it's important to know your administrative distances.... or at least know where to look to see them! The AD of OSPF is 110, which means we can configure a static route to 1.1.1.1 /32, and as long as the AD of the static route is higher than 110, it won't be used unless the OSPF route leaves the routing table. That's why this kind of route is called a "floating" static route - the route "floats" in the routing table and isn't seen unless the primary route leaves the table.

You learned how to write a static route in your CCNA studies, but you also remember that the default AD of a static route is either 1 or 0... and both of those values are less than 110! To change the AD of a static route, configure the desired distance at the end of the ip route command.

R2(config)#ip route 1.1.1.1 255.255.255.255 bri0 ?

<1-255> Distance metric for this route

A.B.C.D Forwarding router's address

name Specify name of the next hop

permanent permanent route

tag Set tag for this route


R2(config)#ip route 1.1.1.1 255.255.255.255 bri0 111

The static route has an AD that's only one higher than that of the OSPF route, but that's enough to make the route "float" and not yet be seen in the routing table.

R2#show ip route

1.0.0.0/32 is subnetted, 1 subnets

O 1.1.1.1 [110/65] via 172.12.123.1, 00:06:44, Serial0

172.12.0.0/24 is subnetted, 2 subnets

C 172.12.12.0 is directly connected, BRI0

C 172.12.123.0 is directly connected, Serial0

Let's see the effect on the routing table when the Serial0 interface is closed.

R2(config)#int s0

R2(config-if)#shutdown


12:04:53: %OSPF-5-ADJCHG: Process 1, Nbr 172.12.123.1 on Serial0 from FULL to DOWN, Neighbor Down: Interface down or detached


12:04:55: %SYS-5-CONFIG_I: Configured from console by console

12:04:55: %LINK-5-CHANGED: Interface Serial0, changed state to administratively down


12:04:56: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down


R2#show ip route

1.0.0.0/32 is subnetted, 1 subnets

S 1.1.1.1 is directly connected, BRI0

172.12.0.0/24 is subnetted, 1 subnets

C 172.12.12.0 is directly connected, BRI0

The floating static route appears in the table, but the ISDN link will not come up until the BRI interface has traffic to send. Let's ping 1.1.1.1 and see what happens. debug dialer was configured on R2 before sending the ping.

R2#ping 1.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

12:16:01: BR0 DDR: Dialing cause ip (s=172.12.12.2, d=1.1.1.1)

12:16:01: BR0 DDR: Attempting to dial 8358661

12:16:01: %LINK-3-UPDOWN: Interface BRI0:1, changed state to up.!!

12:16:01: BR0:1 DDR: dialer protocol up!!

Success rate is 80 percent (4/5), round-trip min/avg/max = 36/37/40 ms

The link comes up and traffic can still reach 1.1.1.1. Once R2 becomes an OSPF neighbor of R1 again, the OSPF route will again become the primary path and the floating static route leaves the routing table.

R2(config)#int s0

R2(config-if)#no shut

R2#show ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

172.12.123.1 1 FULL/DR 00:01:57 172.12.123.1 Serial0


R2#show ip route

1.0.0.0/32 is subnetted, 1 subnets

O 1.1.1.1 [110/65] via 172.12.123.1, 00:00:16, Serial0

172.12.0.0/24 is subnetted, 2 subnets

C 172.12.12.0 is directly connected, BRI0

C 172.12.123.0 is directly connected, Serial0

A floating static route is an excellent "back door" that will keep the ISDN link down while allowing that link to serve as a backup route. Just make sure the ISDN link comes down when you expect it to - always check that with show isdn status!

3.03 PSP Downgrade.

So you're looking a 3.03 PSP Downgrade? well this article may help you out.

First and foremost, you need an unpatched copy of Grand Theft Auto Liberty City Stories.

There is no other way that you can downgrade any PSP over 2.81 without it. Now for some reason people don't seem to appreciate this fact and will spend hours upon hours searching the Internet for other ways to downgrade with out the GTA. Let me save you time, there is no other way to downgrade any PSP above 2.81 with out the unpatched GTA.

In late 2005 a vulnerability was found in the way the PSP version of GTA: Liberty City Stories processes saved games. In December 2005 software was developed to execute unsigned code on PSPs with firmwares 2.00 through 2.60. In April 2006 firmware 2.70 was released and patched the exploit, however, as of January 25, 2007 it was discovered that Sony did not completely patch the exploit, and unsigned code may be run on 3.03 firmware, a 3.03 downgrader was released 3 days after the exploit was found. Also, new copies of GTA: Liberty City Stories patched the exploit as well, preventing it from being executed on other firmware versions. Since then homebrew has advanced to the point that a copy of GTA: Liberty City Stories is no longer needed to run unsigned code except on firmware versions 2.81 to 3.03. Sony has now blocked the GTA exploit for good with the release of the 3.10 firmware update and later subsequent firmware udates.

So how do I know if I have the right GTA for a 3.03 PSP downgrade? Well, it's quite simple really. Get your copy of GTA Liberty City Stories and put it in your UMD drive, now scroll to the game folder and you will see a "UMD update" option. Now, if this says "Update 2.00" then you have an unpatched version, if it says "Update 2.60" then you have the patched version which is no good for a 3.03 PSP downgrade.

Now all you have to do from here is find the 3.03 downgrader, there are a couple of versions around the Internet which you can download and these are relatively easy to follow . Just be sure you download the software from a reputable place as there are some scumbags around who have put fake downgraders up on the Internet so unsuspecting people can download them and brick their PSPs.

Also, make sure you to follow the steps exactly as they are described, this is very important. If you do one thing out of place, or if you put a file and the wrong place you could effectively brick your PSP, so it is vitally important that you follow instructions when you do at 3.03 PSP downgrade.

I hope this article helps you to successfully do a 3.03 PSP downgrade.

The first thing you need to do after a system crash has forced you to reformat your hard drive is to test your PC to make sure whatever caused the crash is still not around to destabilize your system. Once you know your PC is stable, you can begin the process of data recovery after formatting.

Do-It-Yourself Data Recovery After Formatting

The easiest way to get proof of your system’s stability is to upload some non-critical files, so that if they become corrupted you will not have lost anything. Try opening and closing the files, and as long as you do not get a message saying they have been corrupted, you can be fairly certain that your system is functioning normally and storing ant retrieving your data properly. You can move now move on to the data recovery after formatting process.

During the data recovery after formatting process you’ll upload all your recovered data, and for some systems this can take a considerable amount of time. You’ll need to monitor the data recovery after formatting process in case your system flashes messages with question or pinpointing errors on specific files. You’ll need to make a record of every file mentioned in a message, and when the data recovery after formatting upload is complete, do individual checks on each of them. Often an error in one file can compromise the performance of an entire program.

When your data has been completely uploaded, you can go through the key files in each of your programs one at a time, and open them to see if all their data is intact. In some cases, you may have to delete and reinstall some of your software. For more indo see http://www.pcdatarecoveryhelp.com/Data_Recovery_After_Formatting/ on Data Recovery After Formatting.

Software For Data Recovery After Formatting

Another approach to data recovery after formatting is to purchase Windows data recovery software. The data recovery after formatting software can give you step-by step guidance in retrieving data lost sue to formatting, deletion, or partition damage as long as your hard drive has not been physically damaged.

Formatting your hard drive will change your data partitions, and data recovery after formatting software can retrieve data from the previous partitions or even from corrupted sectors. It is designed to support data recovery after formatting for both older file allocation table (FAT) and new technology file systems (NTFS). That covers all Windows operating systems as far back as Windows 98.

Data recovery after formatting can be both challenging and time-consuming. But being able to restore all you key files, either through your own efforts of with the help of user-friendly software, can save you a tremendous amount when compared to the fees of a data recovery specialist.

As computers continue to unfold so do the software programs for computer users.  DVD copy software is one type of program that is becoming an industry standard.  With this type of program even beginners can easily make copies of their favorite DVDs.

In order to copy one disk to another, one must have copy software.   When DVDs first hit the market, software such as this became a reality and now has an interface that is very user-friendly. TV shows and movies can now be massed produced quickly and easily. Your favorite movie can now be duplicated quickly with the right computer software.  You can continue to enjoy your favorite movies as they no longer have to face loss because of over use.  This type of software can make copies that will keep them fresh for a long time.

Staying in touch with family is easier now because of what copy software can do for us.  Easy shipping makes home movies on DVD so easy to enjoy.  Copy software can also fix some scratched disks, thereby fixing a damaged DVD.  The process of transferring VHS onto DVD requires the use of copy software.  VCRs are becoming harder to find and repairing them is expensive because they are being phased out and will soon disappear.  Copy software is one of the necessary ingredients to transfering those VHS recordings.

For those who enjoy creating and sharing home movies, the right software may just be the start of something fun and exciting. The new producer can get their start with short clips and home movies.  It's fun to experiment with all the features of copy software and come up with a work of art.  A new home movie maker may enjoy the process so much that they decide to pursue a career in movies.  

There are a lot of uses for computer software,  from copying a favorite movie, repairing a damaged disk to producing home movies.  Regrettably, the software can also be used illegally which many times gives it a bad rap.  However, when used legally it provides a great way of communicating with friends and relatives or just copying a disk.  By copying movies and data to DVD one can preserve precious memories for years and years.  Whether one buys a computer with the software previously installed or buys it later - it is definitely worth the investment.

I was reading The Big Moo: Stop Trying To Be Perfect and Start Being Remarkable this morning, and I’d recommend a copy of this to anyone who wants to improve their career and their future. And that’s all of us, right?


There was one particular line that really stood out to me: Betting on change is always the safest bet available. That describes life perfectly, but it also describes a career in Information Technology perfectly as well. There is no field in the world that has the constant and never-ending changes that IT does. And every single one of us can look at this as a massive opportunity for personal and professional growth.


Is that how you’re looking at it? I remember when I passed my first certification exam, the Novell CAN, back in 1997. Man, I thought I knew it all then!   But I quickly learned that you’ve got to keep learning in IT. I also learned that if you’re willing to put in the work and make the sacrifices, there’s no other field with the limitless potential for growth and excellence.


Like everyone else, my career has had its ups and downs, but I always kept learning and growing. Today, I’ve got my dream job, working with studI was reading The Big Moo: Stop Trying To Be Perfect and Start Being Remarkable this morning, and I’d recommend a copy of this to anyone who wants to improve their career and their future. And that’s all of us, right?


There was one particular line that really stood out to me: Betting on change is always the safest bet available. That describes life perfectly, but it also describes a career in Information Technology perfectly as well. There is no field in the world that has the constant and never-ending changes that IT does. And every single one of us can look at this as a massive opportunity for personal and professional growth.


Is that how you’re looking at it? I remember when I passed my first certification exam, the Novell CAN, back in 1997. Man, I thought I knew it all then!   But I quickly learned that you’ve got to keep learning in IT. I also learned that if you’re willing to put in the work and make the sacrifices, there’s no other field with the limitless potential for growth and excellence.


Like everyone else, my career has had its ups and downs, but I always kept learning and growing. Today, I’ve got my dream job, working with students and customers just like you – to help you create your own future.


The next 18 months are filled with endless possibilities, particularly with the rapid growth of VoIP and Microsoft Vista on the horizon. There will be those who rationalize their inertia, saying “I’ll never have to support those, so I don’t need to learn them."


There will also be those who see VoIP and Vista as enormous opportunities to learn and advance in their careers and their lives. These people will get started today, learning the fundamentals of Cisco and advancing their networking knowledge in order to be ready for opportunities as they come along.


You can’t start studying and learning when the opportunity arrives – you’ve got to be ready when opportunity knocks. If you’ve been putting off studying for a Cisco or other computer certification – and I know the summer is a really good time for putting off studying – get back on track today.


Because you never know what opportunities are going to come along – but you do know that when they do, you’ve got to be ready to take advantage. After all, opportunity really does knock only once!
ents and customers just like you – to help you create your own future.


The next 18 months are filled with endless possibilities, particularly with the rapid growth of VoIP and Microsoft Vista on the horizon. There will be those who rationalize their inertia, saying “I’ll never have to support those, so I don’t need to learn them."


There will also be those who see VoIP and Vista as enormous opportunities to learn and advance in their careers and their lives. These people will get started today, learning the fundamentals of Cisco and advancing their networking knowledge in order to be ready for opportunities as they come along.


You can’t start studying and learning when the opportunity arrives – you’ve got to be ready when opportunity knocks. If you’ve been putting off studying for a Cisco or other computer certification – and I know the summer is a really good time for putting off studying – get back on track today.


Because you never know what opportunities are going to come along – but you do know that when they do, you’ve got to be ready to take advantage. After all, opportunity really does knock only once!

Planning for success on the CCNA, CCNP, and other Cisco exams is much like taking a trip in your car. You've got to plan ahead, accept the occasional detour, and just keep on going until you get there. But what do you do before you get started?

Create a road map - for success.

If you were driving from one side of the country to another, you certainly wouldn't just get in your car and start driving, would you? No. You would plan the trip out ahead of time. What would happen if you just got in the car and started driving in the hope that you would someday arrive at your final destination? You would never get there, and you'd spend a lot of time wandering aimlessly.

Don't spend your study time and slow your progress by studying for a Cisco exam without planning the trip. Schedule your study time as you would an appointment with a client, and keep that appointment. Make sure that your study time is quality study - turn your TV, iPod, and cell off. If you hit a bump in the road and don't get your certification the first time you take the exam, regroup and create another plan.  Study until you get to the point that on exam day, you know that you are already a CCNA or CCNP and you’re just there at the testing center to make it official.

The journey to success is not a straight line. When you look at a chart that shows a company's financial progress, the line never goes straight up. there are some ups and downs, but the overall result is success. The path to your eventual career and certification exam success may not be a direct one, but the important part is to get started - and to get any journey started, you've got to create a road map for a successful arrival at your destination.

* What kinds of certifications should I consider for a PC Specialist career?

As a PC Specialist, people will rely on your specialized computer training and skills to keep the office running smoothly. You must have the following certifications:

• PC Specialist Certificate
• Microsoft Certified Systems Engineer
• Microsoft Certified Professional

* What kinds of certifications should I consider for a Software Engineer career?

The software engineer designs and develops systems to control and automate manufacturing, business, or management processes. To obtain a position as a Software Engineer, you must have:

• A four-year degree in a computer-related discipline is required for most software engineering positions.

• Certification in various software applications is suggested.

• Training programs are available at community colleges, vocational schools, technical institutes and in the Armed Forces.

Earning and maintaining computer certification is a good way for software engineers to keep their skills up to date. In addition to Microsoft, Novell, Cisco and other high-tech companies, the Institute of Electrical and Electronics Engineers (IEEE) Computer Society offers relevant computer certifications.

* What kinds of certifications should I consider for a Systems Analyst career?

These workers figure out how to use computers to get things done. They tell businesses and other organizations which computers and software to buy, and they decide how to get those tools to work together. To qualify on this position, you must have:

• A four-year college degree in computer science, information science, or management information systems.

• Microsoft Certification and Microsoft Certified Professional (MCP)

* What kinds of certifications should I consider for a Systems Engineer career?

Systems engineering is like putting together a puzzle, matching varied pieces together to make one cohesive whole. Here are some certifications you need to comply:

• BS in systems engineering or other related engineering discipline or an equivalent combination of education and work related experience.

• Novell certifications

Earning computer certification at a prestigious educational institution is impressive. But, if you don't have that kind of money, you may take computer certification training courses anywhere and anyway you wish and then pay to take the exams. Passing the exams is what earns computer certification.

* What kinds of certifications should I consider for a Technical Instructor career?

As a technical instructor, you need to be mature and very oriented towards people. To be considered, you must have the following certifications:

• A four-year degree in a computer-related discipline is required for most software engineering positions.

• CompTIA’s Certified Technical Trainer (CTT+) certification.

* What kinds of certifications should I consider for a Wireless Specialist career?

Career certification programs are critical for aspiring Wireless Specialists. Many are looking for programs that have a complete engineering curriculum that concentrates entirely on wireless application. Some of these are the following:

• Certified Wireless Professional includes application for wireless development, its networking elements and security, and embedded systems. Number of hours needed to complete the certification depends on the institution offering the program, but in most cases these certifications requires minimum of 200 hours lecture in class room and an average of 200 hours in laboratory practice.

• Cisco Security Professional Design Certifications merely concentrates on the perimeter security of the data in the web site, largely to avoid being hacked. Different versions of Web security courses such as DVS 1.0 and DPS 1.0 are available for reference.

* What does certified mean?

There are four accepted meanings of the adjective “certified” but only two of which satisfy the needed meaning. To be certified means to be endorsed with authority by an institution or a person with higher position after one successfully meets certain requirements. Another meaning is that a person is qualified to do a certain job as supported by an appropriate document better known and regarded as a Certification.


* What certifications are there?

If you are pertaining to online certifications, there are lots to be traced. To help you find one best certification that fits your ability and interest, you may log on to reliable sites in the internet. For now, the following are the basic IT certifications:

• IT Auditing
• Document Imaging
• E-Commerce
• Internet/Intranet
• Linux
• Networking
• Printing
• Project Management
• IT Security
• Servers
• Service Technician
• Technical Trainer
• Webmaster


* Who benefits from certification?

Primarily the one given a certification benefits more. Being certified means one can properly function on a certain job. This means, companies will easily hire a person with certification especially when certifications come from a reliable learning institution.

In some ways, the company to which a certified person intends to apply for work will also benefit since the performance of the applying employee is being supported with a certification.


* Is certification better than experience?

The answer for that is a big "No." Certification means training. It is impossible for a person to send himself training without experiencing what it is he intends to do. For this reason, we cannot equate certification from experience since they do not share the same purpose. However, if you already have work experience, a certification is a big help for promotion, recognition and pay raises.

On the other hand, companies are not solely after experience but after educational attainments and performances. In other words, having completed a course as proved by a certification is a chance to be hired.


* Which certification program is best for me?

The best certification program for you is the one that fits your interests and capabilities. Those two factors should be considered above all ese when finding the right and best certification program for you.


* How much will getting certified cost?

Almost all training packages from different training institutions are cost effective. The training cost will depend on the training you want to pursue and in which training institution you intend to enroll. Generally, a trainee should prepare to pay between $100 and $400 for each training program.


* How long will certification take?

There are training institutions that offer a 6-month online training program. The usual training timeframe is one year. This length of training may exceed to a maximum of 2 years depending on the program conducted.


* Do I need a college degree to be certified?

You do not need a college degree to be certified. Some certification programs require one to have at least finished high school upon enrolling in a certain course.


* Will certification really help my career?

A certification may help your career. Nowadays, competition in the jobs is getting tougher. For one to stay in his or her job or to be promoted to a higher position, one factor to consider is his or her educational achievements. That is one reason why mastering your field of work by means of studying and training can be a great boost for your career. That is where a certification program can make or break your career advancement.


* Will I have to go somewhere for my certification training?

While you can find local institutions where you can take classes and tests, most training is done online now. You do not need to go somewhere else for your training. You do not even need to attend classes personally for your lessons. Not only is training done mostly online now, but examinations for certification are also given online.

Like TCP, BGP is connection-oriented.  An underlying connection between two BGP speakers is established before any routing information is exchanged. This connection takes place on TCP port 179.  As with EIGRP and OSPF, keepalive messages are sent out by the BGP speakers in order to keep this relationship alive.

Once the connection is established, the BGP speakers exchange routes and synchronize their tables.  After this initial exchange, a BGP speaker will only send further updates upon a change in the network topology.

The IGP protocols that use Autonomous Systems, IGRP and EIGRP, require prospective neighbors to be in the same AS.  This is not true with BGP. Routers can be in different Autonomous Systems and still exchange routes.  The BGP neighbors do not have to be directly connected, and often are not, but do need to be able to reach the IP addresses they use in their neighbor statements.

A BGP peer that is in the same AS is referred to as an Internal BGP (iBGP) Peer, where a BGP peer in another AS is an External BGP (eBGP) Peer.

A sample iBGP configuration:

Router bgp 100

         Neighbor 10.1.1.2 remote-as 100


A sample eBGP configuration:

Router bgp 100

          Neighbor 10.1.1.2 remote-as 200

Cisco recommends that eBGP peers be directly connected, where iBGP peers generally will not be.

Before we get too much farther into BGP theory, let’s get a configuration started.  You’ll use the router bgp command to configure a router as a BGP speaker.  Right after that, the neighbor command will be used to identify this BGP speaker’s potential neighbors.  (The terms "peer" and "neighbor" are interchangeable in BGP, but it's the neighbor statement that is used to statically define neighbors.  BGP is not capable of discovering neighbors dynamically.)

R1(config-router)#neighbor 172.12.123.3 remote-as 200

While almost all of the neighbor options are just that -- optional -- you do have to specify the BGP AS of the remote router.  BGP has no mechanism to dynamically discover neighbors.  Remember, BGP speakers do not have to be in the same AS to become peers.  To verify that the remote BGP speaker has become a peer, run show ip bgp neighbor.


R1#show ip bgp neighbor

BGP neighbor is 172.12.123.3,  remote AS 200, external link

  BGP version 4, remote router ID 0.0.0.0

  BGP state = Active

  Last read 00:01:39, hold time is 180, keepalive interval is 60 seconds

  Received 0 messages, 0 notifications, 0 in queue

  Sent 0 messages, 0 notifications, 0 in queue

  Route refresh request: received 0, sent 0

  Default minimum time between advertisement runs is 30 seconds

The output here can be a little misleading the first time you read it.  The first highlighted line shows 172.12.123.3 is a BGP neighbor, is located in AS 200, and is an external link, indicating that the neighbor is in another AS entirely.  The second highlighted line shows the BGP state as Active.  This sounds great, but it actually means that a BGP peer connection does not yet exist with the prospective neighbor.

So even though the show ip bgp neighbor output indicated that this is an Active neighbor relationship, that’s not as good as it sounds.  Of course, the reason the peer relationship hasn’t been established is that we haven’t configured R3 yet!


R3(config)#router bgp 200
R3(config-router)#neighbor 172.12.123.1 remote-as 100

Verify the peer establishment with show ip bgp neighbor:

R3#show ip bgp neighbor

BGP neighbor is 172.12.123.1,  remote AS 100, external link

  BGP version 4, remote router ID 172.12.123.1

  BGP state = Established, up for 00:01:18

  Last read 00:00:17, hold time is 180, keepalive interval is 60 seconds

 Local host: 172.12.123.3, Local port: 179  (BGP uses TCP Port 179)

Foreign host: 172.12.123.1, Foreign port: 11007
The peer relationship between R1 and R3 has been established.

Now that you know how the neighbor relationship itself is built, you need to start learning the many options of the neighbor command.  You’ll have to master these to become a CCNP and CCIE!

Passing the BSCI exam and earning your CCNP is all about knowing the details, and when it comes to EIGRP SIA routes, there are plenty of details to know. A quick check in a search engine for "troubleshoot SIA" will bring up quite a few matches. Troubleshooting SIA routes is very challengin in that there's no one reason they occur.

View the EIGRP topology table with the show ip eigrp topology command, and you'll see a code next to every successor and feasible successor. A popular misconception is that we want these routes to have an "A" next to them - so they're active. That's what we want, right? Active routes sound good, right?

Well, they sound good, but they're not. If a route shows as Active in the EIGRP topology table, that means that DUAL is currently calculating that route, and it's currently unusable. When a route is Passive ("P), that means it's not being recalculated and it's a usable route.

Generally, a route shown as Active is going to be there for a very short period of time by the time you repeat the command, hopefully that Active route has gone Passive. Sometimes that doesn't happen, though, and the route becomes SIA - Stuck In Active.

A route becomes SIA when a query goes unanswered for so long that the neighbor relationship is reset. From experience, I can tell you that troubleshooting SIA routes is more of an art form than a science, but there are four main reasons a route becomes SIA:

The link is unidirectional, so the query can't possibly be answered.

The queried router's resources are unavailable, generally due to high CPU utilization.

The queried router's memory is corrupt or otherwise unable to allow the router to answer the query.

The link between the two routers is of low quality, allowing just enough packets through to keep the neighbor relationship intact, but not good enough to allow the replies through.

To sum it up, routes generally become SIA when a neighbor either doesn't answer a query, or either the query or reply took a wrong turn somewhere. I told you it wasn't the easiest thing to troubleshoot!

When you're working on your BCMSN exam on your way to CCNP certification, you'll read at length about how Cisco routers and multilayer switches can work to provide router redundancy - but there's another helpful service, Server Load Balancing, that does the same for servers. While HSRP, VRRP, and CLBP all represent multiple physical routers to hosts as a single virtual router, SLB represents multiple physical servers to hosts as a single virtual server.

In the following example, three physical servers have been placed into the SRB group ServFarm.  They're represented to the hosts as the virtual server 210.1.1.14.

The hosts will seek to communicate with the server at 210.1.1.14, not knowing that they're actually communicating with the routers in ServFarm. This allows quick cutover if one of the physical servers goes down, and also serves to hide the actual IP addresses of the servers in ServFarm.

The basic operations of SLB involves creating the server farm, followed by creating the virtual server.  We'll first add 210.1.1.11 to the server farm:

MLS(config)# ip slb serverfarm ServFarm

MLS(config-slb-sfarm)# real 210.1.1.11

MLS(config-slb-real)# inservice

The first command creates the server farm, with the real command specifying the IP address of the real server.  The inservice command is required by SLB to consider the server as ready to handle the server farm's workload.  The real and inservice commands should be repeated for each server in the server farm.

To create the virtual server:

MLS(config)# ip slb vserver VIRTUAL_SERVER

MLS(config-slb-vserver)# serverfarm ServFarm

MLS(config-slb-vserver)# virtual 210.1.1.14

MLS(config-slb-vserver)# inservice

From the top down, the vserver was named VIRTUAL_SERVER, which represents the server farm ServFarm.  The virtual server is assigned the IP address 210.1.1.14, and connections are allowed once the inservice command is applied.

You may also want to control which of your network hosts can connect to the virtual server.  If hosts or subnets are named with the client command, those will be the only clients that can connect to the virtual server. Note that this command uses wildcard masks.  The following configuration would allow only the hosts on the subnet 210.1.1.0 /24 to connect to the virtual server.

MLS(config-slb-vserver)# client 210.1.1.0 0.0.0.255

SLB is the server end's answer to HSRP, VRRP, and GLBP - but you still need to know it to become a CCNP!  Knowing redundancy strategies and protocols is vital in today's networks, so make sure you're comfortable with SLB before taking on the exam.

To pass the CCNP exams, you’ve got to master Quality of Service, and the first step in doing so is knowing the differences between the different QoS types.

Now this being Cisco, we can't just have one kind of QoS! We've got best-effort delivery, Integrated Services, and Differentiated Services. Let's take a quick look at all three.

Best-effort is just what it sounds like - routers and switches making their "best effort" to deliver data. This is considered QoS, but it's kind of a "default QoS". Best effort is strictly "first in, first out" (FIFO).

An entire path from Point A to Point B will be defined in advance when Integrated Services are in effect. Integrated Services is much like the High-Occupancy Vehicle lanes found in many larger cities. If your car has three or more people in it, you're considered a "priority vehicle" and you can drive in a special lane with much less congestion than regular lanes. Integrated Services will create this lane in advance for "priority traffic", and when that traffic comes along, the path already exists. Integrated Services uses the Resource Reservation Protocol (RSVP) to create these paths. RSVP guarantees a quality rate of service, since this "priority path" is created in advance.

Integrated Services is defined in RFC 1613. Use your favorite search engine to locate a copy online and read more about this topic. It's a good idea to get into the habit of reading RFCs!

Of course, if you've got a lot of different dedicated paths being created that may or not be used very often, that's a lot of wasted bandwidth. That leads us to the third QoS model, the Differentiated Services model. Generally referred to as DiffServ, there are no advance path reservations and there's no RSVP. The QoS policies are written on the routers and switches, and they take action dynamically as needed. Since each router and switch can have a different QoS policy, DiffServ takes effect on a per-hop basis rather than the per-flow basis of Integrated Services. A packet can be considered "high priority" by one router and "normal priority" by the next.

Believe me, this is just the beginning when it comes to Quality of Service. It's a huge topic on your exams and in the real world's production networks, and as with all other Cisco topics, just master the fundamentals and build from there - and you're on your way to CCNP exam success!

STRUCTURE MAC ADDRESS

To earn your CCNP certification and pass the BCMSN exam, you've got to know what HSRP does and the many configurable options.  While the operation of HSRP is quite simple (and covered in a previous tutorial), you also need to know how HSRP arrives at the MAC address for the virtual router - as well as how to configure a new MAC for this virtual router.  This puts us in the unusual position of creating a physical address for a router that doesn't exist!

The output of show standby for a two-router HSRP configuration is shown below.

R2#show standby

Ethernet0 - Group 5

  Local state is Standby, priority 100

  Hellotime 3 sec, holdtime 10 sec

  Next hello sent in 0.776

  Virtual IP address is 172.12.23.10 configured

  Active router is 172.12.23.3, priority 100 expires in 9.568

  Standby router is local

  1 state changes, last state change 00:00:22

R3#show standby

Ethernet0 - Group 5

  Local state is Active, priority 100

  Hellotime 3 sec, holdtime 10 sec

  Next hello sent in 2.592

  Virtual IP address is 172.12.23.10 configured

  Active router is local

  Standby router is 172.12.23.2 expires in 8.020

  Virtual mac address is 0000.0c07.ac05

  2 state changes, last state change 00:02:08

R3 is in Active state, while R2 is in Standby.   The hosts are using the 172.12.123.10 address as their gateway, but R3 is actually handling the workload. R2 will take over if R3 becomes unavailable.

An IP address was assigned to the virtual router during the HSRP configuration process, but not a MAC address.  However, there is a MAC address under the show standby output on R3, the active router.  How did the HSRP process arrive at a MAC of 00-00-0c-07-ac-05?

Well, most of the work is already done before the configuration is even begun.  The MAC address 00-00-0c-07-ac-xx is reserved for HSRP, and xx is the group number in hexadecimal.  That's a good skill to have for the exam, so make sure you're comfortable with hex conversions.  The group number is 5, which is expressed as 05 with a two-bit hex character.  If the group number had been 17, we'd see 11 at the end of the MAC address - one unit of 16, one unit of 1.

The output of the show standby command also tells us that the HSRP speakers are sending Hellos every 3 seconds, with a 10-second holdtime. These values can be changed with the standby command, but HSRP speakers in the same group should have the same timers. You can even tie down the hello time to the millisecond, but it's doubtful you'll ever need to do that.

R3(config-if)#standby 5 timers ?

  <1-254>  Hello interval in seconds

  msec     Specify hello interval in milliseconds

R3(config-if)#standby 5 timers 4 ?

  <5-255>  Hold time in seconds

R3(config-if)#standby 5 timers 4 12

Another important HSRP skill is knowing how to change the Active router assignment.  I'll show you how to do that, and how to configure HSRP interface tracking, in the next part of my CCNP / BCMSN exam tutorial!

Defined in RFC 2281, HSRP is a Cisco-proprietary protocol in which routers are put into an HSRP router group. Along with dynamic routing protocols and STP, HSRP is considered a high-availability network service, since all three have an almost immediate cutover to a secondary path when the primary path is unavailable.

One of the routers will be selected as the primary ("Active", in HSRP terminology), and that primary will handle the routing while the other routers are in standby, ready to handle the load if the primary router becomes unavailable. In this fashion, HSRP ensures a high network uptime, since it routes IP traffic without relying on a single router.

The hosts using HSRP as a gateway don't know the actual IP or MAC addresses of the routers in the group. They're communicating with a pseudorouter, a "virtual router" created by the HSRP configuration. This virtual router will have a virtual MAC and IP adddress as well.

The standby routers aren't just going to be sitting there, though! By configuring multiple HSRP groups on a single interface, HSRP load balancing can be achieved.

Before we get to the more advanced HSRP configuration, we better get a basic one started! We'll be using a two-router topology here, and keep in mind that one or both of these routers could be multilayer switches as well. For ease of reading, I'm going to refer to them only as routers.

R2 and R3 will both be configured to be in standby group 5. The virtual router will have an IP address of 172.12.23.10 /24. All hosts in VLAN 100 should use this address as their default gateway.

R2(config)#interface ethernet0

R2(config-if)#standby 5 ip 172.12.23.10

R3(config)#interface ethernet0

R3(config-if)#standby 5 ip 172.12.23.10

The show command for HSRP is show standby, and it's the first command you should run while configuring and troubleshooting HSRP. Let's run it on both routers and compare results.

R2#show standby

Ethernet0 - Group 5

Local state is Standby, priority 100

Hellotime 3 sec, holdtime 10 sec

Next hello sent in 0.776

Virtual IP address is 172.12.23.10 configured

Active router is 172.12.23.3, priority 100 expires in 9.568

Standby router is local

1 state changes, last state change 00:00:22

R3#show standby

Ethernet0 - Group 5

Local state is Active, priority 100

Hellotime 3 sec, holdtime 10 sec

Next hello sent in 2.592

Virtual IP address is 172.12.23.10 configured

Active router is local

Standby router is 172.12.23.2 expires in 8.020

Virtual mac address is 0000.0c07.ac05

2 state changes, last state change 00:02:08

We can see that R3 has been selected as the Active router ("local state is Active"), the virtual router's IP is 172.12.23.10, and R2 is the standby router.

There are some HSRP values that you'll need to change from time to time. What if we want R2 to be the Active router instead? Can we change the MAC address of the virtual router? I'll answer those questions in the next part of this HSRP tutorial!

CCNP exam success, particularly on the BSCI exam, demands you understand the details of route summarization.  This skill not only requires that you have a comfort level with binary conversions, but you have to know how and where to apply route summarization with each individual protocol.

You also have to know the "side effects" of route summarization.  With OSPF, there will actually be an extra interface created at the point of summarization, and this catches a lot of CCNP candidates by surprise.  Let's take a look at the null0 interface and how it relates to OSPF summarization.

On R1, the following networks are redistributed into OSPF, and then summarized.

interface Loopback16

 ip address 16.16.16.16 255.0.0.0


interface Loopback17

 ip address 17.17.17.17 255.0.0.0


interface Loopback18

 ip address 18.18.18.18 255.0.0.0

interface Loopback19

 ip address 19.19.19.19 255.0.0.0

R1(config)#router ospf 1

R1(config-router)#redistribute connected subnets

R1(config-router)#summary-address 16.0.0.0 252.0.0.0

The summary address appears on R2, a downstream router.

R2#show ip route ospf


O E2 16.0.0.0/6 [110/20] via 172.12.123.1, 00:00:05, Serial0


Let's go back to R1 and look at its OSPF table.

R1#show ip route ospf


O    16.0.0.0/6 is a summary, 00:01:51, Null0

Where did the null0 interface come from, and why is it there?  Packets sent to the null interface are dropped, and in this case, that's a good thing.

When you configure summary routes in OSPF, a route to null0 will be installed into the OSPF routing table.  This helps to prevent routing loops.  Any packets destined for the routes that have been summarized will have a longer match in the routing table, as shown below...

C    17.0.0.0/8 is directly connected, Loopback17

C    16.0.0.0/8 is directly connected, Loopback16

C    19.0.0.0/8 is directly connected, Loopback19

C    18.0.0.0/8 is directly connected, Loopback18

O  16.0.0.0/6 is a summary, 00:01:51, Null0


.. and packets that do not match one of the summarized routes but do match the summary route will be dropped.

Preventing routing loops when performing route redistribution and summarization is vital.  OSPF gives us a little help in that regard in this situation, and as you study more complex redistribution scenarios on your way to the CCNP and CCIE, you'll realize that we'll take all the help we can get!

Passing the BCMSN exam and getting one step closer to the CCNP certification means learning and noticing details that you were not presented with in your CCNA studies. (Yes, I know – you had more than enough details then, right?)   One protocol you’ve got to learn more details about is VTP, which seemed simple enough in your CCNA studies!  Part of learning the details is mastering the fundamentals, so in this tutorial we’ll review the basics of VTP.


In show vtp status readouts, the "VTP Operating Mode" is set to "Server" by default.  The more familiar term for VTP Operating Mode is simply VTP Mode, and Server is the default.  It's through the usage of VTP modes that we can place limits on which switches can delete and create VLANs.

In Server mode, a VTP switch can be used to create, modify, and delete VLANs.  This means that a VTP deployment has to have at least one switch in Server mode, or VLAN creation will not be possible.  Again, this is the default setting for Cisco switches.

Switches running in Client mode cannot be used to create, modify, or delete VLANs. Clients do listen for VTP advertisements and act accordingly when VTP advertisements notify the Client of VLAN changes.

VTP Transparent mode actually means that the switch isn't participating in the VTP domain as Servers and Clients do.  (Bear with me here.)  Transparent VTP switches don't synchronize their VTP databases with other VTP speakers. They don't even advertise their own VLAN information!  Therefore, any VLANs created on a Transparent VTP switch will not be advertised to other VTP speakers in the domain, making them locally significant only. (I know you remember that phrase from your CCNA studies!)

Devices running VTP Transparent mode do have a little something to do with the other switches in the VTP domain, though.  When a switch running in Transparent mode receives a VTP advertisement, that switch will forward that advertisement to other switches in that VTP domain.

Configuring switches as VTP Clients is a great way to “tie down” VLAN creation capabilities to switches that are under your physical control.  However, this occasionally leads to a situation where only the VTP clients will have ports that belong to a given VLAN, but the VLAN still has to be created on the VTP server.  (VLANs can be created and deleted in transparent mode, but those changes aren't advertised to other switches in the VTP domain.)


In the next BCMSN tutorial, we’ll take a look at the details of VTP.

To pass the CCNA exam and earn this important certification, you’ve got to know switching inside and out.  While you’re learning all the basic switching theory, make sure to spend some time with the one of three switching modes Cisco routers can use.

Store-and-Forward is exactly what it sounds like.  The entire frame will be stored before it is forwarded.  This mode allows for the greatest amount of error checking, since a CRC (Cyclical Redundancy Check) is run against the frame before it is forwarded.  If the frame contains an error, it is discarded.  If there’s no problem with the frame, the frame is then forwarded to its proper destination.


While store-and-forward does perform error checking, the delay in processing the frame while this error check is run results in higher latency than the other modes you’re about to read about.  The latency time can also vary, since not all frames are the same size.

Cut-through switching copies only the destination MAC address into its memory before beginning to forward the frame.  Since the frame is being forwarded as soon as the destination MAC is read, there is less latency than store-and-forward.  The drawback is that there is no error checking.

There is a middle ground, fragment-free switching.  Only part of the frame is copied to memory before it is forwarded, but it’s the first 64 bytes of the frame, not just the destination MAC.  (Why?  Because if there is a problem with the frame, it’s most likely in the first 64 bytes.)  There is a little more error checking than cut-through, but not as much latency as with store-and-forward.

Note that the latency of both cut-through and fragment-free is fixed; these modes always look at the first six or 64 bytes, respectively.  Store-and-forward's latency depends on the size of the frame.
Learning the similarities and differences between these modes is an often-overlooked part of CCNA studies.   Spend some time studying this important CCNA topic – you’ll be glad you did!

Whether you're on the road to the CCNA, CCNP, MCSE, or you're on any other computer certification track, the odds are that sooner or later, you're going to fail an exam.  It's happened to almost all of us, yours truly included.   What you have to keep in mind in these times is that success is not a straight line.  You've probably seen charts showing the growth of an industry or a business -- you know, the ones that go from left to right, and look kind of jagged.  The line goes up for a while, then down a bit, then up some more, then down a little.

The key?  While every business has its setbacks, the net result is that the line goes up and progress is made.  That's how you want your certification pursuit and your career to go as well - upward!

I'm not asking you to be happy about failing an exam.  You're allowed to get mad for a few minutes, vow to never take another exam again, and be disappointed.  What you're not allowed to do is stay that way.

If you put your books away in a fit of anger, get them out.  If you took some time off, it's time to get back to work.  Again, there's nothing wrong with being unhappy about failing an exam.  It's how you handle that failure that counts.  No inventor, executive, or entrepreneur has ever been right 100% of the time.  Learn something from your failure.   Was your study time quality study time?  Did you get some hands-on practice with the technology you're studying?  Asking yourself these questions can be tough, but it can be highly valuable in making sure you don't fail the next time.  And there must be a next time - because the one thing you cannot do is quit.

Besides, take it from someone who's been there - your temporary failure makes your eventual success that much sweeter.