[c-nsp] EVC Port Channel Per Flow Load Balancing

[Tassos Chatzithomaoglou]

I'm trying to find more information about the following scenarioof load balancing on a 7600.


      +-----+
      |     |
--PW--+     +==GEC==
      |     +
      +-----+


GEC is EVC based and there is a PW being terminated on the above 7600.The PW is coming through a 10G link from another
router and the GEC is 2x1G.

Now i have three choices:

1) PW terminates on the EVCs under the port-channel interface
2) PW terminates on a vlan interface whose bridge-domain is used on the EVCs under the port-channel interface
3) PW terminates on a vfi with a vlan whose vlan bridge-domain is used on the EVCs under the port-channel interface

According to CCO
(http://www.cisco.com/en/US/docs/routers/7600/install_config/ES40_config_guide/es40_chap4.html#wp1751021), in order to
have per L2 flow load balancing occur on the egress direction towards the GEC i have to use the 1st solution (EVC under
Po), sinceper flow load balancing doesn't work with bridge-domain.

The question is: In the 1st solution do i need a ES+ card on the other direction (towards the core) too, and if yes, why?

I can understand the need for ES+ in solutions #2 and #3, because towards the core the label imposition is happening on
the egress card, but in solution #1 i don't see such a case. Unless something is happening due to egress load-balancing
on the GEC interface.

-- 
Tassos