Subject: Comment on draft-carpenter-flow-ecmp-02

From: Yong Lucy <[email-masked]>
Date: Thu, 17 Jun 2010 17:50:42 -0500

Brian and Shane,

I read the draft. It is well written. 

Here are some comments: 

Text:

   o  At intermediate router(s) that perform ECMP or LAG for packets

      whose source address is a TEP, the hash SHOULD minimally include

      the triple {dest addr, source addr, flow label} to meet the

      [RFC3697] rules.  In practice, since the routers are assumed to be

      unaware of tunneled traffic, this means adding the flow label to

      the existing 5-tuple hash of the outer IP header.

   o  At intermediate router(s) that perform ECMP or LAG for packets

      whose source address is a TEP, the hash MUST minimally include the

      triple {dest addr, source addr, flow label} to meet the [RFC3697]

      rules.  In practice, since the routers are assumed to be unaware

      of tunneled traffic, this means intermediate router(s) SHOULD add

      the flow label to the existing 5-tuple hash of the outer IP

      header.

Two paragraphs are the same except one has "hash SHOULD" and another has
"hash MUST".

Text:

It might be possible to make this classifier stateless, by using a

      suitable modulo(N) hash of the inner IP header's 5-tuple as the

      pseudo-random value.

The document text uses N in referring N paths. It causes a confusion in
using modulo(N) here.  It should be modulo (2**20) for flow ID.

Cheers,

Lucy