From: Darren Johnson (dazza_johnson@yahoo.co.uk)
Date: Fri Dec 07 2007 - 13:29:22 ART
Excellent question! If queue4 is priority queue enabled, it is not used in
the ratio calculations:
30/(10+30+60) = 30% throughput (assuming there was no traffic in the
priority queue).
-----Original Message-----
From: Biggs, Jeff (M/CIO/BIE) [mailto:JBiggs@usaid.gov]
Sent: 07 December 2007 16:24
To: Darren Johnson; ccielab@groupstudy.com
Subject: RE: 3550 scheduling and queueing
This is perfect....thanks. The only question is that if QUEUE 4 is the
priority queue, how would you handle the equation then? Do you add the
100 into the equation?
Jeffrey Biggs
Sr. Network Engineer
USAID
M/CIO/BIE
240-646-5003
jbiggs@usaid.gov
-----Original Message-----
From: Darren Johnson [mailto:dazza_johnson@yahoo.co.uk]
Sent: Friday, December 07, 2007 11:20 AM
To: Biggs, Jeff (M/CIO/BIE); ccielab@groupstudy.com
Subject: RE: 3550 scheduling and queueing
Hey Jeff. WRR (weighted round robin) serves each of the 4 queues in
order.
If priority-queueing is enabled on queue 4, this gets services first (no
matter what), just like PQ with routers.
Packets get assigned to queues depending on the trust state. For
example,
you may want to assign COS 5 traffic received from a trunk link to a
phone,
to queue 4. COS 5 is typically voice traffic, and then use PQ.
You can use the queue bandwidth to restrict certain traffic type to an
allocated amount of bandwidth. For example:
wrr-queue bandwidth 10 30 60 100
Assume we assign COS0/1=Q1, COS2/3=Q2, COS4/5=Q3 and COS6/7=Q4.
If we started a traffic generator sending 100mbps with all traffic set
to
COS=3, it would go to queue 2. From the wrr-queue command, we know queue
2
has 30/(10+30+60+100) = 15% of the bandwidth. Therefore, from the
traffic
generator, only 15mbps of throughput would be achieved. The reason is
that
certain classes of traffic (COS or DSCP) have bandwidth allocated to
them
for use. This prevents lower priority traffic COS1 from using all
traffic
and for example, affecting COS5 throughput.
Hope that makes some sense, I wanted to keep this short but doesn't look
like I have!
Dazzler
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Biggs, Jeff (M/CIO/BIE)
Sent: 07 December 2007 15:31
To: ccielab@groupstudy.com
Subject: 3550 scheduling and queueing
I need some help understanding the concept of WRR scheduling on the
3550. I have looked at several Cisco websites and they have managed to
confuse the heck out of me more than anything. I have Odom and Szigeti
books, but I just can't seem to grasp it when setting the bandwidth of
each queue. Is there any "teachers to the hard of understanding" out
there?
Thanks,
Jeffrey Biggs
Sr. Network Engineer
USAID
M/CIO/BIE
240-646-5003
jbiggs@usaid.gov <mailto:jbiggs@usaid.gov>
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