Re: [spring] WGLC - draft-ietf-spring-srv6-network-programming

"Joel M. Halpern" <jmh@joelhalpern.com> Wed, 04 March 2020 07:09 UTC

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To: "Andrew G. Malis" <agmalis@gmail.com>
Cc: "spring@ietf.org" <spring@ietf.org>, Martin Vigoureux <martin.vigoureux@nokia.com>
References: =?utf-8?q?=3C17421=5F1575566127=5F5DE93B2F=5F17421=5F93=5F1=5F53?= =?utf-8?q?C29892C857584299CBF5D05346208A48D1A3DA=40OPEXCAUBM43=2Ecorporate?= =?utf-8?q?=2Eadroot=2Einfra=2Eftgroup=3E?= <3e2da3a5-5d1b-10a0-aeb4-320c57584241@nokia.com> =?utf-8?q?=3C8259d37e-b460-5f76-1ce6-b0d026bccf6b=40gont=2Ecom=2Ear=3E_=3C2?= =?utf-8?q?0143=5F1583250558=5F5E5E7C7E=5F20143=5F390=5F3=5F53C29892C8575842?= =?utf-8?q?99CBF5D05346208A48DD80E6=40OPEXCAUBM43=2Ecorporate=2Eadroot=2Einf?= =?utf-8?q?ra=2Eftgroup=3E?= =?utf-8?q?=3C5d693a5e-baa0-6ffb-4e39-2695795b7413=40joelhalpern=2Ecom=3E_?= =?utf-8?q?=3C7501=5F1583255845=5F5E5E9125=5F7501=5F499=5F1=5F53C29892C85758?= =?utf-8?q?4299CBF5D05346208A48DD84FF=40OPEXCAUBM43=2Ecorporate=2Eadroot=2Ei?= =?utf-8?q?nfra=2Eftgroup=3E?= =?utf-8?q?=3Cfc5bf8d9-073f-2eff-6041-e1610bf6e116=40joelhalpern=2Ecom=3E_?= =?utf-8?q?=3CDM6PR05MB63484795948C4901C9B7A548AEE40=40DM6PR05MB6348=2Enampr?= =?utf-8?q?d05=2Eprod=2Eoutlook=2Ecom=3E?= <CAOj+MMGE+j7_QnFn-8ZQcU3BKLGEPaXj6hfppxG7-7iFkT3R1g@mail.gmail.com> <CAA=duU3fXaQY--XufYo+CuCnJsTd+bXH2uBbjUUHVJg6tLpzng@mail.gmail.com>
From: "Joel M. Halpern" <jmh@joelhalpern.com>
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Date: Wed, 4 Mar 2020 02:09:27 -0500
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Subject: Re: [spring] WGLC - draft-ietf-spring-srv6-network-programming
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In this case, it is even less relevant.  The PSP for SRv6 does not 
remove the double-processing.  It merely removes the need to ignore the 
SRH at the ultimate node.

Yours,
Joel

On 3/3/2020 6:27 PM, Andrew G. Malis wrote:
> MPLS PHP was invented to solve a particular issue with some forwarding 
> engines at the time - they couldn't do a final pop followed by an IP 
> lookup and forward operation in a single forwarding cycle (it would 
> impact forwarding speed by 50% best case). 20 years later, is this still 
> an issue at the hardware/firmware level? If so, affected implementers 
> should speak up, otherwise there's really no need for PSP.
> 
> Cheers,
> Andy (who was there at the time)
> 
> On Tue, Mar 3, 2020 at 3:11 PM Robert Raszuk <robert@raszuk.net 
> <mailto:robert@raszuk.net>> wrote:
> 
>     Hi Ron,
> 
>      >   MPLS PHP is a clear case of de-encapsulation.
> 
>     Purely looking at technical aspect that is not true at all.
> 
>     MPLS PHP does not remove label stack. MPLS PHP is just used to pop
>     last label. After MPLS PHP packets continue with remaining label
>     stack to the egress LSR (example L3VPN PE).
> 
>      >  I don't think that you can compare MPLS PHP with SRv6 PSP
> 
>     But I agree with that. Both operations have very little in common
>     from packet's standpoint or forwarding apect. Well maybe except
>     "penultimate" word :)
> 
>     Kind regards,
>     R.
> 
> 
>     On Tue, Mar 3, 2020 at 8:30 PM Ron Bonica
>     <rbonica=40juniper.net@dmarc.ietf.org
>     <mailto:40juniper.net@dmarc.ietf.org>> wrote:
> 
>         Folks,
> 
>         I don't think that you can compare MPLS PHP with SRv6 PSP. MPLS
>         PHP is a clear case of de-encapsulation. We do that all the
>         time. In SRv6 PSP, we are removing something from the middle of
>         a packet. That is quite a different story.
> 
>                                                                         
>                                                                         
>                Ron
> 
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