Re: [Bier] Comments on draft-ietf-bier-evpn-02

["Jeffrey (Zhaohui) Zhang" <[e-mail]>]

Hi Sandy,

The PH pop the BIER header and forward the inner packet to the BFER, either natively or over an underlay tunnel depending on whether the BFER is directly connected or not.

In case of vxlan, the inner encapsulation (after the popped BIER header) would be vxlan including its IP/UDP header. The IP destination address would be a multicast address advertised in the Auxiliary Information. The reason for including IP/UDP header is that in case of PHP, the BFER may not be able to know that incoming header is vxlan w/o IP/UDP (when PHP is not used, the BIER header’s proto field can indicate the inner header type).

Having said that, we’re thinking of allocating a dedicated IP multicast address for this purpose, instead of advertising it in the Auxiliary Information.

Jeffrey

From: BIER <[e-mail]> On Behalf Of [e-mail]
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To: Jeffrey (Zhaohui) Zhang <[e-mail]>
Cc: [e-mail]; [e-mail]; [e-mail]; Antoni Przygienda <[e-mail]>; [e-mail]
Subject: Re: [Bier] Comments on draft-ietf-bier-evpn-02


Hi Jeffrey,



Thank you for your respond!



I may misunderstand about the procedure.

Is the multicast known to all PEs overlay?

Is the tunnel between PH router and BFER built in core network?

If there is only one hop between PH router and BFER, and the tunnel is bound to a VPN, then the BFER can decapsulate the packet and forward it correctly.

But if there are multiple hops between PH router and BFER, does the router between PH router and BFER forward the packet correctly according to the multicast address in the tunnel encapsulation?



Thanks,

Sandy


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日 期 ：2020年01月26日 03:07
主 题 ：RE: [Bier] Comments on draft-ietf-bier-evpn-02
Hi Sandy,

Sorry for the late response.
It’s not the PH router that gets a multicast address used to send traffic to the PE. The ingress PE must already use a multicast address known to all PEs.

Jeffrey

From: [e-mail]<mailto:[e-mail]> <[e-mail]<mailto:[e-mail]>>
Sent: Sunday, January 5, 2020 10:33 PM
To: Jeffrey (Zhaohui) Zhang <[e-mail]<mailto:[e-mail]>>; Antoni Przygienda <[e-mail]<mailto:[e-mail]>>; [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Cc: [e-mail]<mailto:[e-mail]>; [e-mail]<mailto:[e-mail]>
Subject: [Bier] Comments on draft-ietf-bier-evpn-02


Hi authors,



Happy New Year!



I am reading the "draft-ietf-bier-evpn-02" draft. I have a question on section 2.1 in "draft-ietf-bier-evpn-02", there is the description: The tunnel endpoint MUST be an IP multicast address and the receiving egress PE MUST be set up to receive and process packets addressed to the address.



The IP multicast address can simplify the forwarding procedure on PHP routers. But I am wondering how the PHP routers will do when it's hard to get a consistent multicast address among the BFERs which can not support BIER forwarding.

And if unicast tunnel can be used here too?



Thanks,

Sandy