IPv6 Hop-by-Hop & Destination Option

[rsivakolundu]

IPv6 Hop-by-Hop and Destination Option for INT Header and INT Metadata transport

[jklr]

@rsivakolundu @mhira1 @mickeyspiegel We can merge this change first, create a v1.x cut, advance INT.mdk to version 2 and merge the two other changes. One thing we need to discuss is where to merge the other future transportations (SRv6, GRE) to. INT v1.x or 2.x, or both?

[rsivakolundu]

I will follow-up on this issue and get back to you guys. This is the first time I am hearing it. Stay tuned.

-Ramesh

On Thu, Oct 4, 2018 at 5:22 PM Andy Fingerhut [email protected] wrote:

@jafingerhut commented on this pull request.

In telemetry/specs/INT.mdk https://github.com/p4lang/p4-applications/pull/56#discussion_r222864221:

Geneve options to be defined for INT Headers.

+### INT over IPv6

I may be woefully out of date on IPv6 extension header behavior, but regarding the option '"INT over IPv6" - INT Headers are carried in the IPv6 packets as Hop-by-Hop option.', I had thought that switches in practice have to punt packets with an IPv6 Hop-by-Hop extension header to the slow path, e.g. software forwarding on a general purpose CPU.

I did a quick search and found that RFC 7045 (published Dec 2013) says this in Section 2.2 "Hop-by-Hop Options":

The IPv6 Hop-by-Hop Options header SHOULD be processed by intermediate forwarding nodes as described in [RFC2460]. However, it is to be expected that high-performance routers will either ignore it or assign packets containing it to a slow processing path. Designers planning to use a hop-by-hop option need to be aware of this likely behaviour.

Is there really a desire to put INT data into a header that will likely result in slow path processing in the network?

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