[c-nsp] Egress bandwidth limiting on 6500 with SUP720

[Tim Rayner]

Hi,

Firstly - thanks to the list I have learned a lot just from reading the
archives.

We are trying to configure our 6500s with SUP720 to limit their rate of
output to an ethernet interface (10/100/1000 on a 6748 module), whilst
continuing to provide some QoS guarantees.  The reasons for this is an
attempt to perform rate limiting before we reach a quite dumb device that
interfaces 100Meg Ethernet to our 34 Mbps WAN.

What I've read on this list, and on the cisco website indicated that the
Sup 720 supports egress policing for a routed interface.  My question is:  
Can it do this, plus guarantee say 2 Mbit/s for our gold class of traffic,
10 Mbit/s for our silver, and use whatever of this is unused up to our
configured 30 Mbit/s ceiling.

It seems clear that we can police on ingress with careful acls to limit 
each of these classes going to the WAN interface, but using this method, 
our default traffic could only use 30 - 2 - 10 = 18Mbit/s, even if there 
were no gold or silver traffic present.

Can anyone help us with our puzzle ?  I've noted that 3750 devices may
support the combination we want using srr-queue commands like so:

interface FastEthernet1/0/4
 no switchport
 ip address 10.166.252.41 255.255.255.252
 srr-queue bandwidth share 1 5 0 9
 srr-queue bandwidth limit 30

I havn't tested this yet on the 3750 - has anybody succeeded with it ? 
Is there a solution for our problem with the 6500/SUP720?

Many Thanks for your time.

Tim.

-- 
==============================================================================
Tim Rayner - Networks Team Leader     | Email : trayner at csu.edu.au
             Charles Sturt University |  Mail : P.O. Box 789, Albury,NSW, 2640
             Phone : (02) 6051 9886   |   Fax : (02) 6051 9919
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