Hi, Acee:

 

Thanks for you to initiate this discussion. Some responses for your questions 
are the followings:

 

 

Best Regards

 

Aijun Wang

China Telecom

 

From: [email protected] <[email protected]> On Behalf Of Acee Lindem 
(acee)
Sent: Wednesday, October 13, 2021 3:06 AM
To: [email protected]
Subject: [Lsr] "Prefix Unreachable Announcement" and "IS-IS and OSPF Extension 
for Event Notification"

 

Speaking as WG Chairs: 

 

The authors of “Prefix Unreachable Announcement” have requested an adoption. 
The crux of the draft is to signal unreachability of a prefix across OSPF or 
IS-IS areas when area summarization is employed and prefix is summarised. We 
also have “IS-IS and OSPF Extension for Event Notification” which can be used 
to address the same use case. The drafts take radically different approaches to 
the problem and the authors of both drafts do not wish to converge on the other 
draft’s method so it is understandable that merging the drafts really isn’t an 
option. 

 

Before an adoption call for either draft, I’d like to ask the WG:  

 

1.       Is this a problem that needs to be solved in the IGPs? The use case 
offered in both drafts is signaling unreachability of a BGP peer. Could this 
better solved with a different mechanism  (e.g., BFD) rather than flooding this 
negative reachability information across the entire IGP domain?

[WAJ] Actually, such mechanism can also be used in other scenarios, for 
example, the tunnel endpoint detection etc.  We have also compared the PUA 
solution with BFD before and all we know that BFD requires many configuration 
overheads and also the burden of process on the participated routers.   BFD is 
actually one “pull” mechanism, it is not efficient as the “push” mechanism that 
proposed in these two drafts.

 

2.       Assuming we do want to take on negative advertisement in the IGP, what 
are the technical merits and/or detriments of the two approaches? 

[WAJ] I thinks both approaches are acceptable. The vendor and operator can 
select either of them to solve the mentioned problem.

 

We’ll reserve any further discussion to “WG member” comments on the two 
approaches.

 

Thanks,
Acee and Chris

 

 

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