Category Archives: Cisco

Cisco traffic shaping

There are a few tools to convert Mb to bits, bytes to bits etc, but I like this one –

Directions are as follows:

direction = input or output
shaped = Speed you want to traffic shape in bits
normal burst = (shaped / 8) * 1.5 
extended burst = (normal burst * 2) 


For example, if you would like to ensure customer has 100Mbps speeds, you would do –

rate-limit input 104857600 19660800 39321600 conform-action transmit exceed-action drop
rate-limit output 104857600 19660800 39321600 conform-action transmit exceed-action drop

Cisco SNR adjustment

Go into global configuration mode and type the following:
service internal
int atm 0
dsl noise-margin (a value between -3 and 3)

Most likely you will need to increase the SNR for stability. You should check the SNR via the command show dsl interface atm0/0/0 or something like show controllers VDSL 0 (or what ever atm you need this doing on). To increase the SNR try settings dsl noise-margin 1 and then check the SNR value again. You can increment it by .5, so maybe 1, then 1.5 etc.. It will resync, and you should see the SNR increase. You can gradually increase until you have a stable connection.

Note that you will get a warning doing this – WARNING: Unsupported Command.  May cause violation to ADSL standards.