Jan 112011
 

First of all, read the disclaimer.

This section is all about small changes that are not important or tricky enough for a blog posting on their own. As such it is likely to grow as I encounter things.

Turning Off Spanning Tree

STP is kind of a noisy protocol, and on small and simple networks it probably is not really needed. To make packet sniffing easier, it may be worth turning off the protocol on all the interfaces … or VLANs :-

router# configure terminal
router(config)#no spanning tree vlan 101
router(config)#no spanning tree vlan 102

Turning Off Cisco Discovery Protocol

For security reasons, or simply because it is unnecessary noise on a network with very little in the way of Cisco devices, you may want to turn off CDP :-

router#configure terminal
router(config)#no cdp run

Autotuning Buffers

According to the documents out there, there is a dark and mysterious art of tuning buffers to optimise performance of your routers. It also says that it isn’t recommended in most situations which must disappoint aspiring übergeeks. However what is less often said is that there is a little option to instruct the router to automatically tune the buffers for optimal performance.

It is likely that it will not make a dramatic improvement, but it is worth turning on :-

router#configure terminal
router(config)#buffers tune automatic

Warm Reboots

Normally when a Cisco router reboots it goes through the whole process of starting up as if it were just powered on (a cold start). This can take quite some time so any option to speed it up is worth considering. Turns out that there is such an option, which instructs the router “just” to reload IOS and restart that way.

It takes effect under two conditions – when the router restarts because of a fault, or when you restart the router manually with the “warm” option (reload warm). To enable this simply turn it on with :-

router#configure terminal
router(config)#warm-reboot