One of the major topics on your CCNA and CCNP exams is Frame Relay. Additionally, Frame Relay is one of the most popular WAN technolgies in today's networks. Getting hands-on experience with Frame Relay in Cisco networks isn't just a good idea, it's a necessity. Let's face it, your employer is going to get a little touchy if you start experimenting with your network's Frame Relay setup.
To practice all your important Frame Relay commands for your exams, you need a working Frame Relay cloud in your home lab. A production network's Frame cloud consists of a lot of Frame switches, but if you choose wisely, a single Cisco router can act as your home lab's entire Frame cloud!
Before we look at the configuration of such a router (hereafter referred to as a "frame relay switch"), let's look at the physical requirements.
The more serial ports you have, the better. You should get a router with at least four serial ports. For frame switching purposes, it doesn't matter if the ports are synchronous or asynchronous - you just need the ports.
You will also need some DTE/DCE cables. The DCE end of the cables will be connected to the frame switch.
A great configuration for a CCNA practice lab is three routers that serve as "production" routers, and a 4th router as a frame relay switch. (You'll want an access server as well, but that's another article.)
What I use in my student and customer pods is a setup where R1 is connected to the frame switch's S1 port, R2 is connected to S2 on the frame switch, and R3 is connected to the frame switch's S3 port.
Now comes the tricky part - the configuration. A frame relay switch's config can be hard to find, so here's a copy of mine. Pay particular attention to the config on ports s1, s2, and s3.
version 12.0
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname FRAME_SWITCH
!
!
ip subnet-zero
no ip domain-lookup
frame-relay switching
!
!
!
interface Ethernet0
no ip address
no ip directed-broadcast
shutdown
!
interface Serial0
ip address 10.1.1.2 255.255.255.0
clockrate 56000
!
interface Serial1
no ip address
no ip directed-broadcast
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clockrate 56000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 122 interface Serial2 221
frame-relay route 123 interface Serial3 321
!
interface Serial2
no ip address
no ip directed-broadcast
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clockrate 56000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 221 interface Serial1 122
!
interface Serial3
no ip address
no ip directed-broadcast
encapsulation frame-relay
logging event subif-link-status
logging event dlci-status-change
clockrate 56000
no frame-relay inverse-arp
frame-relay intf-type dce
frame-relay route 321 interface Serial1 123
!
interface BRI0
ip address 150.1.1.1 255.255.255.252
no ip directed-broadcast
encapsulation ppp
dialer map ip 150.1.1.2 name R2 broadcast 2335552221
dialer-group 1
!
ip classless
!
dialer-list 1 protocol ip permit
!
line con 0
exec-timeout 0 0
logging synchronous
transport input none
line aux 0
line vty 0 4
login
!
end
The key command in the global configuration is frame-relay switching. You must have this configured before you can configure the interfaces.
The interfaces will be configured with the frame route command. Let's take a look at what each value means in the command frame-relay route 122 interface Serial2 221.
frame-relay route - the command
122 - the incoming DLCI on this interface
interface serial2 - the interface the data will be sent out
221 - the outgoing DLCI
This command on S1 means that anything that comes in on this port on DLCI 122 will be sent out interface serial2 on DLCI 221.
It's a good idea to hard-code the interfaces to act as DCEs with the frame intf-type dce command. Since these interfaces are acting as DCEs, the clockrate command is needed for the line protocol to come up.
Once you've configured your frame switch as shown and have configured the frame map statements on the "production" routers, you can test the frame switch configuration. On the frame switch, run the command show frame route .
FRAME_SWITCH#show frame route
Input Intf Input Dlci Output Intf Output Dlci Status
Serial1 122 Serial2 221 active
Serial1 123 Serial3 321 active
Serial2 221 Serial1 122 active
Serial3 321 Serial1 123 active
You should see "active" for all the interfaces. If you see "deleted", make sure your frame switch interfaces are open if they are, check the router configs.
Keep in mind that you can still configure routing protocols to run on ports that you're not using for frame switching. The router we used here had an ethernet port and BRI port, and the BRI port has been configured as part of the production network. Running frame switching does not disable IP routing.
Purchasing and configuring your own frame relay switch is an invaluable part of your Cisco education. By practicing your frame commands and configuring frame connections over your own frame relay cloud, you're polishing your Cisco skills and gaining knowledge that cannot be duplicated by simulator programs.
To your success,
Chris Bryant
CCIE #12933
Showing posts with label configuration. Show all posts
Showing posts with label configuration. Show all posts
Friday, December 26, 2008
Thursday, December 25, 2008
Cisco CCNA Exam Tutorial: Password Recovery Procedures
It might happen on your CCNA exam, it might happen on your production network - but sooner or later, you're going to have to perform password recovery on a Cisco router or switch. This involves manipulating the router's configuration register, and that is enough to make some CCNA candidates and network administrators really nervous!
It's true that setting the configuration register to the wrong value can damage the router, but if you do the proper research before starting the password recovery process, you'll be fine.
Despite what some books say, there is no "one size fits all" approach to Cisco password recovery. What works on a 2500 router may not work on other routers and switches. There is a great master Cisco document out on the Web that you should bookmark today. Just put "cisco password recovery" in your favorite search engine and you should find it quickly.
The following procedure describes the process in recovering from a lost password on a Cisco 2500 router. As always, don't practice this at home. It is a good idea to get some practice with this technique in your CCNA / CCNP home lab, though!
The password recovery method examined here is for 2500 routers.
An engineer who finds themselves locked out of a router can view and change the password by changing the configuration register.
The router must first be rebooted and a “break” performed within the first 60 seconds of the boot process. This break sequence can also vary depending on what program is used to access the router, but is the usual key combination.
The router will now be in ROM Monitor mode. From the rom monitor prompt, change the default configuration register of 0x2102 to 0x2142 with the o/r 0x2142 command. Reload the router with the letter i. (As you can see, ROM Monitor mode is a lot different than working with the IOS!)
This particular config register setting will cause the router to ignore the contents of NVRAM. Your startup configuration is still there, but it will be ignored on reload.
When the router reloads, you’ll be prompted to enter Setup mode. Answer “N”, and type enable at the router> prompt.
Be careful here. Type configure memory or copy start run. Do NOT type write memory or copy run start!
Enter the command show running-config. You’ll see the passwords in either their encrypted or unencrypted format.
Type config t, then use the appropriate command to set a new enable secret or enable password.
Don’t forget to change the configuration register setting back to the original value! The command config-register 0x2102 will do the job. Save this change with write memory or copy run start, and then run reload one more time to restart the router.
This process sounds hard, but it's really not. You just have to be careful, particularly when you're copying the startup config over the running config. You don't want to get that backwards! So take your time, check the online Cisco documentation before starting, get some practice with this procedure with lab equipment, and you'll be ready for success on the CCNA exam and in your production network!
It's true that setting the configuration register to the wrong value can damage the router, but if you do the proper research before starting the password recovery process, you'll be fine.
Despite what some books say, there is no "one size fits all" approach to Cisco password recovery. What works on a 2500 router may not work on other routers and switches. There is a great master Cisco document out on the Web that you should bookmark today. Just put "cisco password recovery" in your favorite search engine and you should find it quickly.
The following procedure describes the process in recovering from a lost password on a Cisco 2500 router. As always, don't practice this at home. It is a good idea to get some practice with this technique in your CCNA / CCNP home lab, though!
The password recovery method examined here is for 2500 routers.
An engineer who finds themselves locked out of a router can view and change the password by changing the configuration register.
The router must first be rebooted and a “break” performed within the first 60 seconds of the boot process. This break sequence can also vary depending on what program is used to access the router, but
The router will now be in ROM Monitor mode. From the rom monitor prompt, change the default configuration register of 0x2102 to 0x2142 with the o/r 0x2142 command. Reload the router with the letter i. (As you can see, ROM Monitor mode is a lot different than working with the IOS!)
This particular config register setting will cause the router to ignore the contents of NVRAM. Your startup configuration is still there, but it will be ignored on reload.
When the router reloads, you’ll be prompted to enter Setup mode. Answer “N”, and type enable at the router> prompt.
Be careful here. Type configure memory or copy start run. Do NOT type write memory or copy run start!
Enter the command show running-config. You’ll see the passwords in either their encrypted or unencrypted format.
Type config t, then use the appropriate command to set a new enable secret or enable password.
Don’t forget to change the configuration register setting back to the original value! The command config-register 0x2102 will do the job. Save this change with write memory or copy run start, and then run reload one more time to restart the router.
This process sounds hard, but it's really not. You just have to be careful, particularly when you're copying the startup config over the running config. You don't want to get that backwards! So take your time, check the online Cisco documentation before starting, get some practice with this procedure with lab equipment, and you'll be ready for success on the CCNA exam and in your production network!
Wednesday, December 24, 2008
Cisco CCNA / CCNP Home Lab Tutorial: Routing On A Frame Relay Switch
When you're preparing for CCNA and CCNP exam success, the best investment you can make is to put together your own home lab. There is no better way to learn Cisco technologies and prepare for the CCNA, BSCI, BCMSN, CIT, and other exams than by working with the many protocols and services you'll need to master in order to pass the exams.
One of the most popular articles I've written over the few years dealt with buying and configuring a Cisco router as a frame relay switch. That article is still available on many websites (including my own), but I want to remind you that just because you configure a router as a frame relay switch, that doesn't mean you can't use it as a home lab router, too!
The global command "frame-relay switching" allows a Cisco router such as a 2520 or 4000 to perform just that, frame relay switching, but this command doesn't disable IP routing. Depending on the router model you use, you will most likely have some extra serial connectors as well as an ethernet port that you can use with your other routers in your home lab.
Let's say you have a 2520 router as your frame relay switch. This switch has four serial ports and an AUI port. You could connect to up to four routers to the 2520's serial ports in order to serve as the frame relay switch for those other routers, and still assign an IP address to the ethernet port and run a routing protocol on the 2520. If you're connecting to less than four other routers as the frame relay switch, you can assign IP addresses to the leftover serial ports as well.
One of the most popular articles I've written over the few years dealt with buying and configuring a Cisco router as a frame relay switch. That article is still available on many websites (including my own), but I want to remind you that just because you configure a router as a frame relay switch, that doesn't mean you can't use it as a home lab router, too!
The global command "frame-relay switching" allows a Cisco router such as a 2520 or 4000 to perform just that, frame relay switching, but this command doesn't disable IP routing. Depending on the router model you use, you will most likely have some extra serial connectors as well as an ethernet port that you can use with your other routers in your home lab.
Let's say you have a 2520 router as your frame relay switch. This switch has four serial ports and an AUI port. You could connect to up to four routers to the 2520's serial ports in order to serve as the frame relay switch for those other routers, and still assign an IP address to the ethernet port and run a routing protocol on the 2520. If you're connecting to less than four other routers as the frame relay switch, you can assign IP addresses to the leftover serial ports as well.
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