RE: Can Multihop BFD be protected using RLFA backup?

<stephane.litkowski@orange.com> Thu, 17 January 2019 09:57 UTC

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From: <stephane.litkowski@orange.com>
To: Muthu Arul Mozhi Perumal <muthu.arul@gmail.com>, "rtg-bfd@ietf.org" <rtg-bfd@ietf.org>
Subject: RE: Can Multihop BFD be protected using RLFA backup?
Thread-Topic: Can Multihop BFD be protected using RLFA backup?
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Date: Thu, 17 Jan 2019 09:57:13 +0000
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Hi,

I think that the fact that “control” packets can benefit of FRR is really implementation dependent. It is also linked to the place where BFD packets are created (RP or LC).
From a theoretical point of view, nothing prevents FRR to be used as for any packet generated by the router itself.
Regarding the encapsulation, if your BFD client is using RFC5883, this will not change during FRR, the FRR will just push labels on top independently.

Again, the possibility to get FRR is really implementation dependent, as the forwarding decision of the BFD packet may not be taken by the network processor of the LC.

Brgds,

From: Rtg-bfd [mailto:rtg-bfd-bounces@ietf.org] On Behalf Of Muthu Arul Mozhi Perumal
Sent: Thursday, January 17, 2019 10:16
To: rtg-bfd@ietf.org
Subject: Can Multihop BFD be protected using RLFA backup?

Hi All,

Multihop BFD (RFC 5883) packets are sent over UDP/IP. The encapsulation used is identical to single hop BFD (RFC 5881) except that the UDP destination port is set to 4784.

Now, suppose on the ingress node there is no IP/LFA backup path for the destination address tracked by multihop BFD, but there exists an an RLFA backup path to that destination. In this case, is multihop BFD expected to be protected using the RLFA backup path i.e should multihop BFD packets be sent over the RLFA backup path if the primary path goes down?

If multihop BFD packets are to be sent over the RLFA backup path, what encapsulation should the ingress use? The encapsulation specified in RFC 5883 or the encapsulation specified in RFC 5884 (MPLS BFD)?

Please let me know you opinion.

Regards,
Muthu

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