The MPLS WG Archive

["Tissa Senevirathne" <tsenevir@hotmail.com>]

Why are we saying ECMP hash is to pick a number between 1 and 6 ? Why not 64 
?

In my opinion ECMP is entirely a local implementation issue. And at WG 
requirement level one sentence to say
" Any load balancing policies implemented MUST not mis order packets"
is adequate


>From: Hummel Heinrich <Heinrich.Hummel@icn.siemens.de>
>To: "'erosen@cisco.com'" <erosen@cisco.com>,        Shahram Davari 
><Shahram_Davari@pmc-sierra.com>
>CC: "'Eric Osborne'" <eosborne@cisco.com>,        George Sheng 
><george_s97@hotmail.com>, scullptor@yahoo.com,        mpls@UU.NET
>Subject: AW: your mail Date: Tue, 2 Jul 2002 16:25:37 +0200
>
>It  gets weirder  and weirder: The MPLS WG invents a label stack, but does 
>not care at all that any of the
>deeper nested labels may ever be signalled/carried by means of a 
>Label-TLV/object (no public comments to my
>Hierarchical LSPs, draft-hummel-mpls-hierarchical-lsp-01.txt).
>
>However it is ok, to "steal" the deepest nested label and call it 
>"VC-label" for indexing
>some VRF at some remote PE. Furthermore it is ok, to "steal" the very same 
>label for hashing.
>
>Independent from what is clean and what is quick&dirty, I cannot detect any 
>sense in giving a hash-meaning to the bottom label at all.
>
>
>
>Heinrich Hummel
>Siemens
>
>-----Ursprüngliche Nachricht-----
>Von: Eric Rosen [mailto:erosen@cisco.com]
>Gesendet: Dienstag, 2. Juli 2002 16:06
>An: Shahram Davari
>Cc: 'Eric Osborne'; George Sheng; scullptor@yahoo.com; mpls@UU.NET
>Betreff: Re: your mail
>
>
>Shahram> To do ECMP, you need to  assign hashed values to egress ports. 
>This
>Shahram> assignment is the hash state that I said you need.
>
>A hash is  a function that maps  some sequence of octets into  a sequence 
>of
>integers.  If you want to split  traffic over six paths, while ensuring 
>that
>all packets  with the  same bottom label  travel the  same path, you  need 
>a
>function that maps  a 20 bit quantity  into a number from 1-6.   There is 
>no
>need to maintain state of any kind.




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