Re: [PWE3] [mpls] WG Last Call for draft-ietf-pwe3-endpoint-fast-protection-01 - RFC4447

[Loa Andersson <[e-mail]>]

Yakov,


On 2014-08-08 16:02, Yakov Rekhter wrote:
> Loa,
>
>> Authors, Mingui, Stewart
>>
>> On 2014-08-08 04:46, Mingui Zhang wrote:
>>> Hi Stewart,
>>>
>>> I think authors would say the S-PE stitching method involves
>>> the control plane processing during the repair procedure. They
>>> emphasized their method uses data plane & local repair, which
>>> can be faster.
>>> Here, I want to raise one issue:
>>
>> It seems that we take it for granted that the method proposed on this
>> draft is faster than e.g. the e2e protection a la mpls-tp. Why is that?
>
> To answer your question let me quote from "Network Recovery" by JP
> Vasseur, Mario Pickavet, Piet Demeester (Section 5.8.1, page 336):
>
>    With global protection, rerouting is performed by the head-end
>    LSR, which means that this requires for the head-end LSR to receive
>    the failure indication to reroute the affected traffic onto their
>    respective backup paths (whose paths have been precomputed and
>    signaled). So in terms of recovery time, the delta between global
>    and local protection is the failure indication signal propagation
>    time to the head-end LSR.
>
> Yakov.
>

Well, I won't argue that this is what is said in the book, but it is
not what I asked about.

mpls-tp runs e.g. 1:1 or 1:n, i.e. 1 working lsp (or pw) is protected
by one or more pre-established  lsp's or pw's. detection time can be
as low as 10ms and the switch over is far shorter.

While I understand that the draft is much more resource conservative,
what is the foundation to claim that is faster?

/Loa


-- 


Loa Andersson                        email: [e-mail]
Senior MPLS Expert                          [e-mail]
Huawei Technologies (consultant)     phone: [phone]