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

[Tom Herbert <[e-mail]>]

On Sun, May 5, 2019 at 7:49 PM Ron Bonica <[e-mail]> wrote:
>
> Mark,
>
> As the header chain (including encapsulations) get longer, the packet becomes less ASIC friendly.
>
Ron,

I'm dubious that just a two byte header for EtherIP or four byte
header will be a problem especially in light of the fact that segment
routing header is already adding significantly to packet overhead with
an arbitrary list of sixteen byte quantities.

Tom

> 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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