Hi Jorge,

The current text in pbb-evpn draft doesn’t prohibit the use of “sticky-bit”. 
The initial advertisement for a BMAC can be sent with this bit set (where the 
sequence # is zero). For flushing CMAC addresses in PBB-EVPN, MAC mobility 
extended community is used with sequence number incremented (for shared BMACs). 
These two functions are separate and are two different things (learning BMAC 
versus flushing CMACs). Are you concern about a scenario where right after 
configuration of the shared BMAC, there is a failure for Single-Active MHD/MHN, 
where another BMAC advertisement with MAC mobility is sent, and the RR only 
sends the latter advertisement?

Cheers,
Ali

From: <Rabadan>, "Jorge (Jorge)" 
<jorge.raba...@alcatel-lucent.com<mailto:jorge.raba...@alcatel-lucent.com>>
Date: Tuesday, March 31, 2015 at 7:28 PM
To: 
"draft-ietf-l2vpn-pbb-e...@tools.ietf.org<mailto:draft-ietf-l2vpn-pbb-e...@tools.ietf.org>"
 
<draft-ietf-l2vpn-pbb-e...@tools.ietf.org<mailto:draft-ietf-l2vpn-pbb-e...@tools.ietf.org>>
Cc: "bess@ietf.org<mailto:bess@ietf.org>" <bess@ietf.org<mailto:bess@ietf.org>>
Subject: [bess] PBB-EVPN draft - use of sticky bit in mac mobility ext. com.

Dear authors,

In PBB-EVPN we advertise PE shared BMACs or dedicated (per-ES) BMACs. Either 
way, I believe it is a good practice to advertise them as ’static’ i.e. along 
with the ’sticky’ bit. That provides a natural protection against BMACs that 
might be learnt locally and are not ‘managed’.

In RFC7432, when the sticky bit is set, the sequence number is zero.
For PBB-EVPN, that means that when shared BMACs are used and per-ISID load 
balancing multihoming is in place, the shared BMACs cannot be advertised as 
static (since the sequence number is used as a CMAC flush notification).

Since the PE BMACs are not subject to mobility procedures and are by nature 
‘static’ and managed, would it be possible to explicitly allow in the pbb-evpn 
draft the advertisement of the sticky bit along with a sequence number, when 
the mac-mobility extended community is used for CMAC flush notification?

This can be optional and would allow an extra level of security in a PBB-EVPN 
network.
If you agree with that, I can provide a text if needed.

Looking forward to your feedback.
Thank you.
Jorge
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