Re: dscp markings on icmp request

 QoS is a unidirectional thing... As is the idea about markings. Your
message to me is one thing. My reply back to you is ENTIRELY different.
So unless we have an application that pre-sets that stuff, or QoS
policies on BOTH sides making whatever changes we'd like to see, then
you'd expect exactly what you are seeing.

HTH,

Scott Morris, CCIEx4 (R&S/ISP-Dial/Security/Service Provider) #4713,

JNCIE-M #153, JNCIS-ER, CISSP, et al.

JNCI-M, JNCI-ER

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Ovidiu Neghina 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 Sun Jan 10 2010 - 14:59:03 ART