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Cell Relay Retreat>MPLS WG Archive>month:2003-Mar> msg00378



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[PWE3] MPLS PID

  • From: Curtis Villamizar <curtis@fictitious.org>
  • Date: Thu, 27 Mar 2003 13:06:56 -0500
  • cc: "'curtis@fictitious.org'" <curtis@fictitious.org>, "'Thomas D. Nadeau'" <tnadeau@lucidvision.com>, "'George Swallow'" <swallow@cisco.com>, "W. Mark Townsley" <townsley@cisco.com>, "Andrew G. Malis" <Andy.Malis@vivacenetworks.com>, "'mpls@uu.net'" <mpls@UU.NET>, tnadeau@cisco.com


In message <4B6D09F3B826D411A67300D0B706EFDE0115C839@nt-exch-yow.pmc-sierra.bc.
ca>, Shahram Davari writes:
> >I don't feel obligated to answer nonsense questions.  No one has
> >proposed putting a CRC in the PID.
> 
> First of all I meant computing CRC over the first 20 byte of payload header
> and comparing it to the suspected IP CRC in octets 11 and 12 of the payload.
> If they match then it is IPv4, if not it is something else (similar procedure
>  for IPv6)
> 
> Secondly I am proposing it now. Is there a problem? I feel my procedure is fa
> r superior to just checking 4 bits to decide whether the payload is IP or not
> . 


It would be a lot more efficient to just put in a PID that states what
the payload type is rather than CRC the header.  This way if it isn't
IPv4 or IPv6, we know what it is.

I don't think we should jam the PID into 4 bits.  Two or four bytes
would be a lot more reasonable (using ethertype for example).

Curtis

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