Subject: MRT algorithm and architecture draft updates

From: Chris Bowers <[email-masked]>
Date: Thu, 15 Oct 2015 18:12:35 +0000

Dear RTGWG,

We have made significant updates to the MRT algorithm and architecture drafts which can be found at the links below.
https://tools.ietf.org/html/draft-ietf-rtgwg-mrt-frr-algorithm-06
https://tools.ietf.org/html/draft-ietf-rtgwg-mrt-frr-architecture-07

Below is summary of the main changes.

draft-ietf-rtgwg-mrt-frr-algorithm-06:

1) We found some topologies involving named proxy nodes attached to two different blocks, where the function for determining MRT next-hops for named proxy nodes in the -05 version of the draft does not produce disjoint paths to the named proxy node.  The -06 version of the draft modifies the Select_Proxy_Node_NHs() and Select_Alternates_Proxy_Node() functions to correct this. 

2) The Python code included in the draft has been extended to cover the case of multi-homed prefixes as well as destination nodes outside of the MRT Island, using the updated versions of the Select_Proxy_Node_NHs() and Select_Alternates_Proxy_Node() functions.  The updated Python code can also be found on github at:
https://github.com/cbowers/draft-ietf-rtgwg-mrt-frr-algorithm/blob/master/src/mrt_lowpoint_draft_text.py

3) The -05 version of the draft had a TODO item to address how the MRT algorithm works when there are broadcast interfaces.  The -06 version adds a new section to address broadcast interfaces.

4) In the -06 version, we added cases to Select_Alternates() to handle cases where F (the failed primary next-hop node) is unordered with respect to S(the PLR).  This can occur when the link between F and S is signaled to be MRT_INELIGIBLE.  

draft-ietf-rtgwg-mrt-frr-architecture-07

1) The -07 version of the architecture draft changes the method for determining if an Island Neighbor is loop-free with respect to the MRT Island.  The new version is described in the text, as well as a comparison with the method in the -06 version.

2)   The IANA requests for MRT red and blue MPLS MT-IDs were moved back to draft-ietf-mpls-ldp-mrt since it makes more sense for a document in the MPLS WG to contain the IANA request for values from a registry created by the MPLS WG.

We appreciate any feedback from the WG on these changes. 

Thanks,
Chris