[Idr] WG Adoption for draft-zhu-idr-bgp-ls-path-mtu (11/1/2020 to 11/16/2020)

[Susan Hares <[e-mail]>]

This begins a 2 week WG adoption call for 

draft-zhu-idr-bgp-ls-path-mtu-04.txt (11/1 - 11/16/2020). 

 

The authors should send in an IPR statement for this draft 

by 11/5 so the WG can include the IPR status in their decision. 

 

You can access the draft at: 

https://datatracker.ietf.org/doc/draft-zhu-idr-bgp-ls-path-mtu/

 

Since this draft is reference by an existing IDR draft

I've included a bit of background below to help you place  

this draft into the larger context of the SR additions to BGP-LS

and the draft-ietf-idr-tunnel-encaps-19.txt.

 

This draft does continue BGP-LS additions.  if you 

are opposed to any BGP-LS additions rather than 

this specific addition, please make that clear in your 

comment in this discussion.   

 

The authors requested a WG adoption at IETF 108.  

The IDR co-chairs thank the authors for their patience.   

This draft has been delayed by process of having a 

new document shepherd (Sue Hares) come up to speed

on draft-ietf-idr-tunnel-encapsulation. 

 

Cheers, Sue 

 

Background

===========

Segment Routing technology creates SR tunnels that are 

directly overlaid on MPLS or SRv6.  While existing MPLS technology 

(LDP and RSV-TE) provides mechanisms to negotiate path MTU

based on individual link MTU limits, the Segment Routing (SR) 

on BGP-LS Link Attribute does not pass information on 

MTU size per link.   

 

draft-ietf-idr-sr-policy-path-mtu-02.txt sends PATH MTU 

information in the tunnel-encapsulation attribute for the tunnel type  

SR-Policy that handles segment routing (SR) paths.       

However, it lacks the information to create a reasonable 

Path size since the BGP-LS Link Attribute does distribute

this information. 

 

The draft proposes adding a new sub-TLV for MTU size 

to the BGP-LS Link Attribute TLV, and 

draft-ietf-idr-sr-policy-path-mtu-02.txt mentions this 

draft as one possible way to distribute the per link 

MTU.  

 

Questions for the authors might be: 

a) Are there ways to pass IGP link MTUs in 

the IGPs?  If so, is this needed in BGP-LS

 

b) What other mechanisms pass link MTU?