Re: [spring] SRv6 Network Programming: ENH = 59

[Ron Bonica <[e-mail]>]

Mark,

As the header chain (including encapsulations) get longer, the packet becomes less ASIC friendly.

Allocating a new Next Header value for Ethernet may be less painful than introducing a new encapsulation.

                                                       Ron



Juniper Internal

> -----Original Message-----
> From: Mark Smith <[e-mail]>
> Sent: Sunday, May 5, 2019 9:37 PM
> To: Xiejingrong <[e-mail]>
> Cc: Tom Herbert <[e-mail]>; Ron Bonica
> <[e-mail]>; SPRING WG <[e-mail]>; 6man
> <[e-mail]>
> Subject: Re: [spring] SRv6 Network Programming: ENH = 59
> 
> On Mon, 6 May 2019 at 11:15, Xiejingrong <[e-mail]>
> wrote:
> >
> > Hi Tom,
> >
> >
> >
> > Number 97 is a choice but it has 2 bytes wasting.
> >
> >
> 
> It seems strange to me that as bandwidth is constantly getting cheaper, people
> seem to be trying harder and harder to use less of it.
> The trade-off is increased code complexity and CPU at each of the hops at the
> end of the links.
> 
> It is has been my understanding that bandwidth has been getting cheaper
> faster than CPU for quite a number of years, has that flipped around?
> 
> 
> >
> > Jingrong
> >
> >
> >
> > From: ipv6 [mailto:[e-mail]] On Behalf Of Tom Herbert
> > Sent: Monday, May 06, 2019 9:11 AM
> > To: Ron Bonica <rbonica=[e-mail]>
> > Cc: SPRING WG <[e-mail]>; 6man <[e-mail]>
> > Subject: Re: SRv6 Network Programming: ENH = 59
> >
> >
> >
> >
> >
> > On Sun, May 5, 2019, 5:47 PM Ron Bonica
> <rbonica=[e-mail]> wrote:
> >
> > Folks,
> >
> > According to Section 4.4 of draft-ietf-spring-srv6-network-programming-00,
> when processing the End.DX2 SID, the Next Header must be equal to 59.
> Otherwise, the packet will be dropped.
> >
> > In the words of the draft, "We conveniently reuse the next-header value 59
> allocated to IPv6 No Next Header [RFC8200].  When the SID corresponds to
> function End.DX2 and the Next-Header value is 59, we know that an Ethernet
> frame is in the payload without any further header."
> >
> > According to Section 4.7 RFC 8200, " The value 59 in the Next Header field of
> an IPv6 header or any  extension header indicates that there is nothing
> following that header.  If the Payload Length field of the IPv6 header indicates
> the presence of octets past the end of a header whose Next Header field
> contains 59, those octets must be ignored and passed on unchanged if the
> packet is forwarded."
> >
> > Does the WG think that it is a good idea to reuse the Next Header value 59?
> Or would it be better to allocate a new Next Header value that represents
> Ethernet?
> >
> >
> >
> > Tom,
> >
> >
> >
> > There's already ETHERIP number (97). Why not use that?
> >
> >
> >
> > Tom
> >
> >
> >
> >
> >                                                           Ron
> >
> >
> > Juniper Internal
> >
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