Re: QoS on 3550

From: ccie2be (ccie2be@nyc.rr.com)
Date: Thu Apr 22 2004 - 13:52:26 GMT-3


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 Wygand
  To: ccie2be ; Group Study
  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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