10-15-2008 04:57 AM - edited 03-06-2019 01:56 AM
Hi all,after reading the cisco srnd on the campus lan design model, it says that QOS policies should be applied at the distribution layer, my question is, what kind of policies? as I thought that most qos is done at the edge, with regards to marking etc. Would we just trust the DSCP mark at the distrubution layer? and would we need to trust this also between the distrubution and core layers ?
10-15-2008 05:16 AM
Errrm Carl,
you say you have read the SRND for QoS - specifically the Campus QoS Design?
You ask "it says that QOS policies should be applied at the distribution layer,"
On page 1 of the Campus QoS Design under "QoS Design Overview" just above figure 2-2 a thrid of the way down the page - there is a big chunk of text, I will post for you:-
"So where is QoS required in campus?
Access switches require the following QoS policies:
â¢Appropriate (endpoint-dependant) trust policies, and/or classification and marking policies
â¢Policing and markdown policies
â¢Queuing policies.
Distribution and core switches require the following QoS policies:
â¢DSCP trust policies
â¢Queuing policies
â¢Optional per-user microflow policing policies (only on supported platforms)"
Did you miss this when you read the document?
10-15-2008 08:09 AM
Hi there
So if my access layer switches, do a 802.1p to dscp marking, then all I have to do at the distribution and core layer is to trust this?
what about queuing? why would i need to change this at the dist/core layer?
10-15-2008 10:54 AM
Yes.
Because - if you have followed the guide and are using the switches recommended on the Dist/Core - then you will know they do not support, Policing, Dropping, Shaping. They queue, and buffer with thresholds using weighted tail drop.
10-16-2008 12:08 AM
can you expand on this a little at all ?
10-16-2008 12:37 AM
If you go for a 3750 for the distibution layer:-
http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoSDesign.html#wp999803
or a 4500:-
http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoSDesign.html#wp1000390
And the 65xx for the core layer:-
http://www.cisco.com/en/US/docs/solutions/Enterprise/WAN_and_MAN/QoS_SRND/QoSDesign.html#wp1032596
ALL FROM THE QoS SRND.
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