[bess] Comments on draft-sajassi-bess-evpn-ip-aliasing-02

[[e-mail]]

Hi Jorge,






This is the detailed explanation of the question I asked in the IETF 111 meeting. 


In page 7 of slides-111-bess-sessa-evpn-ip-aliasing, when leaf-5 send traffic to leaf-2,  how does leaf-2 find the corresponding ARP entry for 20.0.0.2 or 20.0.0.1 or 20.1.1.3 ?


I guess the GW-IP 1.1.1.1 will be advertised as overlay index along with the ESI.



But the draft-ietf-bess-evpn-prefix-advertisement-11 does not define an IP Prefix Advertisement Route with both GW-IP and ESI both as overlay index.


I suggest that this should be updated if you want to do so.


And the preference of ESI overlay index should be considered higher than GW-IP overlay index for Leaf-5's sake.


But the preference of ESI overlay index should be considered lower than (or maybe they should both be used? ) GW-IP overlay index for Leaf-2's sake


These are new rules that can't be found in draft-ietf-bess-evpn-prefix-advertisement-11 .






But on the contary,  if the IP Prefix Advertisement Route has a GW-IP overlay index,


It can support the same protection procedures without any ESI overlay index.


( The details to do such protection using GW-IP overlay index I have described in draft-wang-bess-evpn-arp-nd-synch-without-irb-06. )


So I don't get the point why we need two redundant overlay index?


Can you clearify it?






Maybe an IP Prefix Route Style with a GW-IP overlay index is engough here.


And such Route Style is in compliance with  draft-ietf-bess-evpn-prefix-advertisement-11 already.






Another question is that: If the ESI overlay index is advertised, when will the IP A-D per EVI route of Leaf-2 be withdrawn?


When the IRB interface on Leaf-2 fails?


When one of the three ACs fails?


When all of the three ACs fails?


If you want to do so, I suggest that the ESI-1 to be configured onto the IRB interfaces,


But in Figure 2 of  draft-sajassi-bess-evpn-ip-aliasing-02, I see the ESI is configured on the ACs of the BDs.






Is anything I have misunderstood?






Best,


Yubao