[c-nsp] what is it with 3550s?

Randy McAnally rsm at fast-serv.com
Mon Feb 22 14:14:10 EST 2010

We've always used in/out policing without any issues on physical interfaces on
our 3750G's.


---------- Original Message -----------
From: Jon Lewis <jlewis at lewis.org>
To: TCIS List Acct <listacct at tulsaconnect.com>
Cc: cisco-nsp <cisco-nsp at puck.nether.net>
Sent: Mon, 22 Feb 2010 12:50:30 -0500 (EST)
Subject: Re: [c-nsp] what is it with 3550s?

> On Sun, 21 Feb 2010, TCIS List Acct wrote:
> > We've got a boatload of 3550-EMI's (for colo/server aggregation duties) and 
> > are looking at replacing them in the next 12-24 months  The C3750G-24/48-E 
> > series seem to be a good upgrade path (all gig ports, layer3 routing, IPv6 
> > support, fairly easy to source on the used market) -- curious as to why you 
> > said they didn't look viable...
> I haven't played with the 3750 line, but assuming it's similar in 
> software to the 3560, the trouble with them (vs the 3550), 
> particularly in a colo/server aggregation setup, is a serious lack 
> of flexibility in per-port policing.
> With the 3550, you can use input/output service-policy to police 
> each port to arbitrary bandwidh.  If you want to limit a customer to 
> 2mbit/s in both directions, it's trivial to do.
> With the newer switches, cisco no longer supports per-port egress 
> policing.  Instead, you have srr-queue bandwidth limit [10-90],
>  which limits the egress port speed to 10-90% of physical speed. 
>  i.e. srr-queue bandwidth 10 on a 100mbit port results in 10mbit/s.  
> That would be the lowest "policed" rate you can configure for 
> egress.  If you can live with that, then it's not so bad, because 
> you can come up with the %'s for all the other rates you'd want to 
> limit ports to.
> Also, because the egress bandwidth limit is configured for the 
> "whole port" you can't use service-policy and ACLs to police some 
> traffic but not other, or police certain types of traffic to 
> different rates on the same port.
> ----------------------------------------------------------------------
>   Jon Lewis                   |  I route
>   Senior Network Engineer     |  therefore you are
>   Atlantic Net                |
> _________ http://www.lewis.org/~jlewis/pgp for PGP public 
> key_________ _______________________________________________ cisco-
> nsp mailing list  cisco-nsp at puck.nether.net 
> https://puck.nether.net/mailman/listinfo/cisco-nsp archive at 
> http://puck.nether.net/pipermail/cisco-nsp/
------- End of Original Message -------

More information about the cisco-nsp mailing list