Subject: [Bier] [bier] comments on draft-hu-bier-bfd-03

From: <[email-masked]>
Date: Mon, 4 Mar 2019 14:01:18 +0800 (CST)

Hi authors,

Thank you for your update! IMO using BFD technology in BIER is useful. 

But I have comments with some sections in this version(03):

1. Section 4.1, if the Target SI-Bitstring TLV is mandatory? 

From my understanding this draft is different with "draft-ietf-bier-ping". 

The function defined in this document "draft-hu-bier-bfd" is unidirectional. 

BFER need to know the liveness of BFIR in order to monitor the link between BFIR and BFER. 

BFER can get the information includes Sub-domain-id, BS Len. etc through the underlay protocols. 

So I don't understand the usage of target SI-Bitstring.

And because the Bitstring is different among different multicast flows. Which one should be taken? 

2, Section 4.2, why IGP extensions are used to advertise the discriminator? 

IMO only edge routers should know the discriminator of BFIR. 

Is it necessary for BFRs to know the discriminator? 

And what is the situation for BFRs to use the BFIR's discriminator? 

If it is more suitable to advertise the discriminator by overlay protocols?

Thanks,

Sandy