Re: cos rewriting on switch

Thanks Mark. You pointed me to the right direction to undestand this.

Just a question: why you used value "101111000" for the ping test? All that
counts are first three bits 101, decimal 5. The rest of the TOS byte can be
anything. I just did extended ping from R2 with Type of service 160, 170 and
191 (all tose numbers begin 101 in binary) and it is received on R1 as cos5,
as expected. Does it make sense ?

On 10 November 2010 10:50, <mwcombs_at_comcast.net> wrote:

> Jack,
>
>
>
> I specified in my previous email that you have to mark your service class
> 184 on your ping tests. I meant TOS (type of service) not to be confused
> with dscp values.
>
>
>
> TOS values:
>
> binary 101110, the full TOS value is 101111000 which is decimal 184, or in
> hex 0xB8.
>
> - Mark
>
> ----- Original Message -----
> From: mwcombs_at_comcast.net
> To: "Jack Router" <pan.router_at_gmail.com>
> Cc: ccielab_at_groupstudy.com
> Sent: Wednesday, November 10, 2010 9:30:45 AM
> Subject: Re: cos rewriting on switch
>
> Jack,
>
>
>
> Your traffic leaving R2 must mark it's traffic with cos5 or 0x2e in hex
> which
> equates to an precedence 5.B Is your router2 even marking your traffic
> properly?B I would setup a monitoring port on port 2 which connects to
> router
> 2 to validate the packets coming in are indeed marked properly.B My guess
>
> they are not.
>
>
>
> Another thought is why are you trying to look for a greated cos value then
> 0
> on an ICMP packet?B When you do your pings are you using extended options
> commands and specifing service class 184?B You will need to do this if you
> want to mark your packet with cos vaule of 5.B If not your pings will just
> be
>
> normal pings.
>
>
>
> - Mark Combs
>
>
>
>
>
>
>
>
>
>
>
>
> ----- Original Message -----
> From: "Jack Router" <pan.router_at_gmail.com>
> To: ccielab_at_groupstudy.com
> Sent: Tuesday, November 9, 2010 10:31:18 PM
> Subject: cos rewriting on switch
>
> Hello all,
>
> I have a question about cos rewriting on a switch. Here is scenario:
>
> R1(f0/0.100)-----dot1q------(f0/1)SW1(f0/2)------access-------(f0/0)R2
>
> On R1 I configured class maps and policy map to identify what cos is
> received.
> SW1 has NO mls qos enabled or any cos configuration.
>
> When I ping R1 from R2 i see that R1 receives packets marked with cos0. Why
> ? Packets that leave R2 are not tagged with cos value, why then R1 receives
> packets cos0 ?
> Is cos0 a synonym of no cos marking ?
>
>
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Received on Wed Nov 10 2010 - 12:04:19 ART