From: Scott Morris (swm@emanon.com)
Date: Mon Dec 20 2004 - 17:25:03 GMT-3
The switch-priority is in reference to the four hardware queues that are
associated with each ethernet port.
Look at the defaults:
Table 2-9 Default DSCP-to-Switch Priority
DSCP Value/Switch Priority
0-15/0
16-31/1
32-47/2
48-63/3
DSCP values 0-15 covers IP precedence values 0 and 1, which is COS 0 and 1
by default.
DSCP values 16-31 covers IP precedence values 2 and 3, which is COS 2 and 3
by default.
So on and so forth.
'show mls qos interface queueing' will show the defaults.
HTH,
Scott Morris, MCSE, CCDP, CCIE4 (R&S/ISP-Dial/Security/Service Provider)
#4713, JNCIP, CCNA-WAN Switching, CCSP, Cable Communications Specialist, IP
Telephony Support Specialist, IP Telephony Design Specialist, CISSP
CCSI #21903
swm@emanon.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
ccie2be
Sent: Monday, December 20, 2004 10:37 AM
To: Group Study
Subject: 3550 QoS and Switch Priority
Hi guys,
I came across an option for the above command that I can't figure out.
See this link:
http://www.cisco.com/univercd/cc/td/doc/product/lan/c3550/12225se/3550cr/cli
1
.htm#wp1862902
This option allows you to map dscp values to switch priority.
mls qos map dscp-switch-priority <dscp-list> to <switch-priority>
The CR says for this option the following:
Define the DSCP-to-switch-priority map. This map generates the priority of a
request to the switch fabric when using a priority-aware switch fabric.
For dscp-list, enter up to eight DSCP values, with each value separated by a
space. The range is 0 to 63. Then enter the to keyword.
For switch-priority, the range is 0 to 3.
I've got some questions about this.
1) Is this actually something that can be done on 3550?
2) What does "switch-priority" mean in this context? (Notice that the range
of values for switch priority is only 0 to 3 which doesn't sound like this
switch priority has anything to do with the Spanning Tree Protocol.)
3) What do they mean by "priority-aware switch fabric" and does the 3550
have this?
4) If the 3550 has this what's the default dscp to switch-priority mapping?
I spent a couple hours already trying to find out the answers to these
questions but the only references I've found were related to the 6500 switch
fabric.
Any help would be appreciated.
TIA, Tim
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