Re: [mpls] Some comments on draft-kompella-mpls-entropy-lables

[George Swallow <[e-mail]>]

I disagree with the text below.  It is my understanding that a lot of
equipment does ECMP by looking for EOS, checking the first nibble for 0100b
and if true running the usual IPv4 load-balancing.  Only if it is not 0100b
(and maybe 0110b) does it actual use some portion of the label stack.  This
is why in PW, the first nibble of the CW is 0000b.

It seems to me the only way to be sure that this will work is to define a
new FEC in LDP. This would be equivalent to an IP FEC, but say that you must
load balance on the label stack only.

...George

4.2.  Transit LSR

   Transit LSRs have no change in forwarding behavior.  For load
   balancing, transit LSRs SHOULD use the whole label stack (e.g., for
   computing the load balance hash).  Transit LSRs MAY choose to look
   beyond the label stack for further load balancing information;
   however, if entropy labels are being used, this may not be very
   useful.  In a mixed environment (or for backward compatibility), this
   is the simplest approach.

   Thus, transit LSRs are almost unaffected by the use of entropy
   labels.  If transit LSRs were programmed to use a subset of the label
   stack, they may have to be reconfigured to use the full stack.  But
   otherwise, no changes are needed.

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