Limit network bandwith on router interfaces

[sejoberbo]

Hello,

I'm in process of building a small network using one cisco router and 2-3 switches.

I will have (on my router outside interface fa0/0) 4Mbps/4Mbps download/upload available.

My available adress space is 32 public adresses, so there will be no NAT/PAT.

What I want to do is to use two internal ports (fa0/1 and fa0/2) to divide this space into two networks.

Then I need to limit this available bandwith to 2Mbps (upload AND download) for each port (network),

but, when one network is not using it's maximum up/down rate I need to make all thats left from bandwith available to other network.

This is intended because I plan to have only one device in first network which will be used for web conferencing and needs min 2Mps to operate

without any lagging.

In the second network I will have an FTP server which will need all available bandwith when device for conferencing is not in use.

I need your suggestion which router to use and part of configuration also, if possible.

Thank you in advance.

[Adrian Lazar]

Hi,

You could mark the traffic from each of the two networks using DSCP, let's say AF21 for FTP and AF41 for Video. After that you can configure a policy-map for the interface towards your provider that looks like this:

policy-map Queueing

class Video

priority 60% (here the percent depends on the amount that you want to guarantee for Video traffic)

class FTP

bandwidth remaining percent 90%

class-map Video

match ip dscp AF41

class-map FTP

match ip dscp AF21

The effect of the above is that if you have Video traffic it will have at least 60% of the bandwidth (can have it all if there is no FTP traffic) and if you have FTP traffic it will get the rest, but when Video stops then FTP can have all the bandwidth.

To mark the traffic you should simply configure one policy-map under each of your inside interfaces that marks all traffic with AF41 or AF21 (this applies only if you have just the Video Server on that segment).

policy-map Mark_Video

class class-default

set ip dscp AF41

Best regards,

Adrian