From: Kenneth Wygand (KWygand@customonline.com)
Date: Thu Apr 22 2004 - 15:41:19 GMT-3
I just tried this out. You need to enable "mls qos" to do anything with
COS or TOS values. COS or TOS will not "pass through" the switch unless
you have this configured globally.
Yes, COS does automatically map to IP Precedence values by default
through "mls qos cos-to-dscp" (COS 5 maps to DSCP 40 which is backwards
compatible with IP Precedence 5.
Yes, you can set the _raw_ value of the TOS field through an extended
ping. However since this is the raw value, IP Precedence of 5 is
represented through "160" and DSCP EF is represented through "184" (you
need to do the binary conversion).
I think I answered all the questions here. If anyone else has any other
questions, let me know and I'll try to answer!
Thanks!
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"I am not really smart. I just stick with problems longer."
-Albert Einstein
Custom Computer Specialists, Inc.
"Celebrating 25 Years of Excellence"
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Thursday, April 22, 2004 12:52 PM
To: Kenneth Wygand; Group Study
Subject: Re: QoS on 3550
Hey Ken,
I don't think this can be fully tested by marking pkts on the 2500. I
think you have to test this on the 3550.
Can you set this up? rtr1 ----> sw1--trunk sw2 ---> rtr2 or rtr1
--> sw --> rtr2
Try setting the 3550 port connected to rtr1 to mark icmp pkts to cos 5.
Then configure logging on rtr2 connected to the 3550 using an
access-list that logs all icmp pkts with a ip prec = 5. (On the 3550,
frames marked with cos = 5, I think are automatically mapped to ip prec
= 5.)
I think, but I'm not sure, that mls qos has to be enabled on the 3550
for this to work. Maybe you can confirm this.
Now, ping the 2nd rtr, and see what pkts are logged.
After testing what happens with frames marked on the 3550 with cos
settings, try changing the marking to ip prec, and then dscp, and
repeating experiment. If you do this, don't forget to change the log
access-list on the 2nd rtr so that you can see what the 3550 does in
each case.
HTH, Tim
----- Original Message -----
From: Kenneth <mailto:KWygand@customonline.com> Wygand
To: ccie2be <mailto:ccie2be@nyc.rr.com> ; Group Study
<mailto:ccielab@groupstudy.com>
Sent: Thursday, April 22, 2004 12:21 PM
Subject: RE: QoS on 3550
I'm trying to test this out as we speak. I'm trying to set the IP
Precedence in a route map assigned to a local policy in a 2500 series
router, but I'm receiving the following... is this because I cannot set
ISL or DOT1Q encapsulation on a 2500-series router? I believe I should
be able to set the TOS bit on any platform because there is a TOS field
in all IP packets.
<snip>
ip local policy route-map SETFLASH
route-map SETFLASH permit 10
set ip precedence flash
r1#ping 10.0.0.2
*Mar 1 00:12:43.951: %SYS-5-CONFIG_I: Configured from console by
console
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
*Mar 1 00:12:47.163: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy match
*Mar 1 00:12:47.167: IP: route map SETFLASH, item 10, permit
*Mar 1 00:12:47.171: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy reject
ed -- normal forwarding.
*Mar 1 00:12:49.163: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy match
*Mar 1 00:12:49.167: IP: route map SETFLASH, item 10, permit
*Mar 1 00:12:49.167: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy reject
ed -- normal forwarding.
*Mar 1 00:12:51.163: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy match
*Mar 1 00:12:51.167: IP: route map SETFLASH, item 10, permit
*Mar 1 00:12:51.171: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy reject
ed -- normal forwarding.
*Mar 1 00:12:53.163: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy match
*Mar 1 00:12:53.167: IP: route map SETFLASH, item 10, permit
*Mar 1 00:12:53.167: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy reject
ed -- normal forwarding.
*Mar 1 00:12:55.163: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy match
*Mar 1 00:12:55.167: IP: route map SETFLASH, item 10, permit
*Mar 1 00:12:55.167: IP: s=10.0.0.1 (local), d=10.0.0.2, len 100,
policy reject
ed -- normal forwarding.
Success rate is 0 percent (0/5)
</snip>
Any ideas?
Kenneth E. Wygand
Systems Engineer, Project Services
CISSP #37102, CCNP, CCDP, ACSP, Cisco IPT Design Specialist, MCP, CNA,
Network+, A+
Custom Computer Specialists, Inc.
"I am not really smart. I just stick with problems longer."
-Albert Einstein
Custom Computer Specialists, Inc.
"Celebrating 25 Years of Excellence"
-----Original Message-----
From: ccie2be [mailto:ccie2be@nyc.rr.com]
Sent: Thursday, April 22, 2004 11:57 AM
To: Group Study
Subject: QoS on 3550
Hi guys,
I'm trying to understand something which has me confused.
Recall these facts:
At layer 2, only ISL or 802.1q trunks have fields to carry layer 2 QoS
info.
Regular ethernet frames don't and can't carry any QoS info.
Given the above,
Q1) Can cos be set on frames coming into or going out of regular access
port on a 3550?
Q2) If so, how does this work?
Q3) Can someone confirm that's there's no problem or Gotcha's on
setting layer 3 QoS on frames coming into or leaving a regular access
port?
Thanks in advanced, Tim
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