The "bandwidth" interface command

thomasdzubin · ‎06-19-2008

My WAN port is 100Mbps full duplex, however my ISP rate-limits me to 3Mbps. Is there any disadvantage to using the command "bandwidth 3000" on my WAN interface? without that command, when I do a "show interface", all I ever see is "reliability 255/255, txload 1/255, rxload 1/255", but when I adjust the bandwidth settings, I get to see some numbers other than "1" in my txload and rxload

Are there any disadvantages to using the "bandwidth" command? It doesn't seem to affect anything other than the calculations that show the txload and rxload.

Jon Marshall · ‎06-19-2008

Thomas

The bandwidth command affects 2 things mainly.

1) Routing protocol calculations such as for EIGRP/OSPF which take in account bandwith in their best path calcuations.

2) QOS calculations.

If neither of these are an issue for you or it would make no difference if you did alter it then yes you can use the correct bandwidth under the interface.

Jon

Joseph W. Doherty · ‎06-19-2008

As Jon notes, and you have noticed with the txload and rxload, the bandwidth statement "informs" the router what the "logical" bandwidth is on the link. Far from being a disadvantage, its usually a good thing to inform the router what the bandwidth on a link might actually be.

PS:

BTW: If you're not already doing so, and if your device supports it, you might benefit from shaping your 100 Mbps port to 3 Mbps. E.g.

Fastethernet #

shape 3000000 (I think speed is set in bps)