Frame Relay is the major WAN connection in CCIE lab. Luckily, Cisco removed ATM, on which I failed my last attempt.
Some things to be careful when using Frame Relay. First of all, Inverse-ARP. It is good to disable frame relay inverse-arp after you configure the frame-relay encapsulation, and before you enable the interface. If the interface is enabled before you configure the encapsulation type, reboot the router after disabling inverse-arp.
Second thing to take care is the interface type. Be aware of the issue when one side of the link is point-to-point, and the other side is multipoint. When enabling triggered RIP, it works only under point-to-point link.
Last thing to mention is PPP over Frame Relay. We configure a virtual interface, configure the ip address under the virtual interface, and tie it to the dlci. We can configure PPP authentication under the virtual interface as well.
Some useful commands for frame relay:
sh frame pvc
sh frame map
Friday, July 27, 2007
Thursday, July 26, 2007
The Ultimate Router Simulator -- Dynamips
I have been preparing the Cisco CCIE Routing & Switching practical test.
Normally, for people to take the test, they will buy the equiptments and setup a home lab, except for some luckiers, who can practise on equiptments from work.
Some websites provide the remote lab, which you can rent to practise on, but it is still expensive. Averagely, people spend 2000 hours preparing for the test.
I do not have the fund to buy all the equiptments (normally, the lab would cost $20k or more).
Then about six months ago, I found the website providing router simulator, DYNAMIPS. I was amazed by how powerful it is. I have used some router simulators before, but what they do is to simulate the output when you type in some command. It is ok for people to take CCNA test, or maybe even CCNP, but definately not CCIE.
The Dynamips simulates the router hardware environment, just like VMWARE or VirtualPC. Then you run Cisco IOS on top of it. It supports a lot of types of routers, like Cisco 7200, 3660 & 3640, 3725 & 3745, and 2600 series. It supports some useful modules as well, like Serial interfaces module, and Ethernet interfaces module. When you configure the Ethernet module, it is running as a 16-port IOS Ethernet switch. It can simulate Frame Relay as well.
Thanks to my manager, who paid for my IPEXPERT workbook. When I got the book, I realized that including the 4 switches, I need to run 15 routers.
There is a limitation for the simulator. The numbers of router you can simulate depends on the OS you are using, your CPU, the size of your RAM, and the memory you allocate to each router. 32-bit Windows has 2GB memory limit for a single instance. And when you enable multiple instances, the CPU utilization is very high.
Once in the lab, I simulated 11 routers on a server with 2 Xeon CPUs with 4 GB RAM, and running on 2 instances, the CPU utilization went to 100%.
Then I decided to invest on a fast computer. I bought the Intel Q6600, Quad Core, with 4GB RAM. This time when I test it with 15 3725 routers, to my excitement, the CPU utilization is only 1 ~ 3%.
When I started the ipexpert workbook, I found that the IOS switch (router with NM-16ESW module) is not powerful enough. It does not have all the features required.
Luckily enough, I found 2 Catalyst 3550 and 2 Catalyst 3560 switches in the store room of my company. Connecting them up with fibers and crossover cables...
Finally, I have my own CCIE lab! Thanks to Chris (the guy who programmed dynamips)! Thanks to my manager!
Normally, for people to take the test, they will buy the equiptments and setup a home lab, except for some luckiers, who can practise on equiptments from work.
Some websites provide the remote lab, which you can rent to practise on, but it is still expensive. Averagely, people spend 2000 hours preparing for the test.
I do not have the fund to buy all the equiptments (normally, the lab would cost $20k or more).
Then about six months ago, I found the website providing router simulator, DYNAMIPS. I was amazed by how powerful it is. I have used some router simulators before, but what they do is to simulate the output when you type in some command. It is ok for people to take CCNA test, or maybe even CCNP, but definately not CCIE.
The Dynamips simulates the router hardware environment, just like VMWARE or VirtualPC. Then you run Cisco IOS on top of it. It supports a lot of types of routers, like Cisco 7200, 3660 & 3640, 3725 & 3745, and 2600 series. It supports some useful modules as well, like Serial interfaces module, and Ethernet interfaces module. When you configure the Ethernet module, it is running as a 16-port IOS Ethernet switch. It can simulate Frame Relay as well.
Thanks to my manager, who paid for my IPEXPERT workbook. When I got the book, I realized that including the 4 switches, I need to run 15 routers.
There is a limitation for the simulator. The numbers of router you can simulate depends on the OS you are using, your CPU, the size of your RAM, and the memory you allocate to each router. 32-bit Windows has 2GB memory limit for a single instance. And when you enable multiple instances, the CPU utilization is very high.
Once in the lab, I simulated 11 routers on a server with 2 Xeon CPUs with 4 GB RAM, and running on 2 instances, the CPU utilization went to 100%.
Then I decided to invest on a fast computer. I bought the Intel Q6600, Quad Core, with 4GB RAM. This time when I test it with 15 3725 routers, to my excitement, the CPU utilization is only 1 ~ 3%.
When I started the ipexpert workbook, I found that the IOS switch (router with NM-16ESW module) is not powerful enough. It does not have all the features required.
Luckily enough, I found 2 Catalyst 3550 and 2 Catalyst 3560 switches in the store room of my company. Connecting them up with fibers and crossover cables...
Finally, I have my own CCIE lab! Thanks to Chris (the guy who programmed dynamips)! Thanks to my manager!
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