Network Ninja

Working from the my last couple of EIGRP posts I am going to try and crystallize some of the material found by working through questions found in Stewart, B,D., Gough, C (2008). CCNP BSCI Official Exam Certification Guide, Fourth Edition. Indianapolis: Cisco Press.

Explain the meaning of the command ip bandwidth-percent eigrp 63 100?

The purpose of the command ip bandwidth-percent eigrp 63 100 is when one has many Virtual Circuits (VCs) and there is not enough bandwidth at the access speed to support the aggregate bandwidth. The subinterfaces must be configured with a much lower speed than the real speed of the circuit.

For example on multiple Frame Relay links, lets say 5 in all, all with 64 kbps guaranteed (CIR) you know you can “garauntee” this aggregate 128 kbps bandwidth but , but when the sun shines, the wind blows in the right direction and everyone exhales at once in the office you might get more or less than 2 Mbits meaning aggregate bandwidth of 10 Mbits.

In this case we use ip bandwidth-percent eigrp 63 100 to indicate to the EIGRP process that it can still function, by adjusting it from the default 50% bandwidth to use 100% of the bandwidth (so EIGRP can use 256 kbps) for Autonomous-System 63 on the interface which it is configured. This is done because chances are very high that we are in most cases going to receive somewhere between 384 kbps and 512 kbps rather than our CIR of 128 kbps.

One uses this command because the bandwidth command does not reflect the true speed of the link.

Resources:

Stewart, B,D., Gough, C (2008). CCNP BSCI Official Exam Certification Guide, Fourth Edition. Indianapolis: Cisco Press.

Notes and Notices:

This is a part of my personal BSCI notes and research to assist myself in learning and understanding the concepts and theory for the BSCI exam. I learn by making notes reading and writing things down and wish to file them where I can’t lose them. These notes are not to be seen, judged or mistaken for replacements to Cisco recognized and authorized training which I personally support and attend and suggest you undertake if you are going for the BSCI Certification.