Re: dscp markings on icmp request

Thank you all for your explanations.

Ovidiu

2010/1/11 Nicolas Leiva <nicolasleiva_at_gmail.com>:
> If no marking is involved in the network, sending a ping (request) with a
> certain IP Precedence should come back (Reply) with this value intact (a
> requirement for IPv4 routers: RFC1812)...... You mentioned from CE to CE, so
> probably experimenting the (QoS) Pipe Mode.
>
> Not sure what you mean by real life, but if you mean pinging sites on
> Internet, it's very common that your Service Provider will re-write your IP
> Precedence to 0 (Best Effort) on your Internet Access port.
>
>
> Nicolas
> http://ccie-en-espanol.blogspot.com/
>
>
> On Sun, Jan 10, 2010 at 1:08 PM, Ovidiu Neghina <o.neghina_at_gmail.com> wrote:
>>
>> Hi,
>> I have noticed doing some captures in my labs that when doing a ping
>> from a cisco router to another the dscp markings of icmp reply are
>> identical .For example if a ping from one CE to another CE with IPP=5
>> the reply comes back with IPP5. This with no special configuration .
>> I did test in real life pinging various sites from windows xp with
>> ping -v 136 for example (136 is the value of the TOS byte =>AF41 in
>> DSCP) . some sites reply with DSCP=0, others with same marking, others
>> with different marking.
>> Is any rule , rfc on icmp about his ? I did not find enaything pointing to
>> this
>>
>> br,
>> Ovidiu
>>
>>
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Received on Mon Jan 11 2010 - 18:26:02 ART