tree e264d3ce489a150fbb50aeee066e55c5d367321d
parent 6ecf56d21cd38498d1ebf3c5322b4e86c45db9a3
author Saurav Das <sauravdas@alumni.stanford.edu> 1497393354 -0700
committer Charles Chan <rascov@gmail.com> 1501879780 -0700

CORD-1419 CORD-1425 CORD-1496 CORD-639 Changes for dual-ToRs

Introduces the concept of edge-pairs (or paired-ToRs) which
can have some subnets/prefixes reachable by both ToRs.
   - Each ToR can also have prefixes reachable only by itself,
     even though it is part of an edge-pair.
   - The paired link between ToRs in an edge-pair is ignored
     for ECMP calculations.
   - Required a change in how destinations and next-hops are stored.
     The neighborSet is now a destinationSet, and no longer carries
     next-hop info, which is now stored in NextNeighbors. As a result,
     the DestinationSetNextObjectiveStoreKey and ECMP group id do not
     change as next-hops come and go.
   - It is now possible to have buckets in hash groups with the same
     outport but different labels.
   - DefaultRoutingHandler has been rearraged to be more readable, and
     clearly highlight the three major ways that routing changes can
     happen in the network.

Also fixes the case where config is added after switches connect to the controller.

Change-Id: I7ce93ab201f6ef2c01cbe07a51ee78cd6a0a112e