Subject: RE: [PWE3] MPLS PID

From: "Naidu, Venkata" <[email-masked]>
Date: Thu, 27 Mar 2003 14:44:02 -0500

Dave,

-> Hang on.... 
-> Using CRC as a sanity check (ensuring somthing starting 
-> with 0x04 is actually an IP packet) prior to load balancing 
-> is the suggestion, an imperfect improvement assuming the 
-> first nybble cannot be completely trusted as authoritative 
-> indication of payload type. Suggesting that it is then 
-> vulnerable to malicious attacks is a non-sequitor. 

  More than malicious attacks, my strong objection is
  because of the approximations in the suggestion. If
  all that we want to achieve is to find the payload type
  then that should not be *guessed* by some approximations
  or probabilistic method. Propose something concrete to
  identify the payload type. In networking all such 
  approximation algorithms are called hacks. In the history
  there is such a hack called henk-hack already :-)

-> The goal is to avoid misordering flows across the network. 

  If that is the goal, why even to bother to find the payload
  type. Search for and reserve a bit (just a bit) - for example
  from EXP bits (if not used from Diffserv) - then ask the
  sender to set the bit as NL (no-load-balance bit). This acts
  just as good as Don't fragment (DF) bit in IP Header. But,
  I suppose that won't suffice for your requirement.

-> A rogue packet is a flow unto itself and would only 
-> impact its neighbors if load spreading was somehow stateful.

  If that is the case, we shouldn't have spent so much time 
  in security. The difficult thing is to find whether the 
  packet is *real-rogue* packet or *rogue packet relative to IP*

Venkata.