[c-nsp] 7600/Cat6500 LAN Card QoS

[Mack McBride]

If you have policing enabled it is unlikely you will queue packets.
The input and output queues are handled by port asics.
The policing is handled on the PFC/DFC and ignores CoS/DSCP so queues 
are not relevant for policing.  

SIP/SPAs handle congestion differently and offer highly improved 
queue management but they cost a lot more.

Most ISPs reset DSCP/COS so they are ignored.
Check with your specific provider but this is general policy.

LR Mack McBride
Network Architect
Viawest, Inc.

*** Opinions offered are my own and do not reflect policies or opinions
of my employer ***

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Dmitry Kiselev
Sent: Monday, December 07, 2009 7:14 AM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] 7600/Cat6500 LAN Card QoS

Hello!

Could somebody in the list explain me egress QoS nuances for
C7600/Cat6500 LAN Cards? Lets assume I have t1/1 port on 6708 card
connected to my ISP. According to SLA, ISP sell me 500M CIR with
tail droping all above. To prioritize most important traffic with
some DSCP markings I should place it to port priority queue
using  "wrr-queue dscp-map 7" and of couse enable dscp mapings
using "mls qos queue-mode mode-dscp".  To tell the router/switch
use only 500M and queue/schedule all congested traffic I should
apply service-policy with police 500M command. (I don't know how
it could be done in any other supported way).  According to
several 7600/6500 QoS presentations available in the net, policing
is done in PFC (DFC, if ingress card equiped with) and queueing/
scheduling is doen in Port ASIC on egress card. So, all my traffic
will be policed and tail droped before priority queue and all other
queueing things like WRED come in play.

Is it true or I miss something important and initialy went in
wrong direction?

P.S. My question regarging C7600, 6708 and 12.2(33)SRC, but
seems hardware concept is the same for Cat6500/C7600 with PFC3/DFC3
and any modern IOS.

Thanks!

-- 
Dmitry Kiselev
_______________________________________________
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/