RE: END SID Without SRH

[Ron Bonica <[e-mail]>]

Tom,

Close, but not exactly.

I am surprised that a document whose title is " IPv6 Segment Routing Header (SRH)" describes behavior changes that occur when the SRH is not present.

Personally, I think that this is an indication that the draft does more than define the SRH, but I am willing to accept that I am in the minority on this point.

                                                    Ron



Juniper Internal

-----Original Message-----
From: Tom Herbert <[e-mail]> 
Sent: Tuesday, June 11, 2019 3:19 PM
To: Ron Bonica <[e-mail]>
Cc: 6man WG <[e-mail]>
Subject: Re: END SID Without SRH

On Fri, Jun 7, 2019 at 7:26 AM Ron Bonica <rbonica=[e-mail]> wrote:
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> Darren,
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> This isn’t a blocker. Just a surprising behavior that never struck me before.
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> Assume that an SRv6 router receives a packet whose destination address is an END SID. The packet does not contain any extension headers at all.
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> If the next header after the IPv6 header is IPv4 or IPv6, the router removes the outer header and forwards the payload.
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> If the next header after the IPv6 header is TCP, the router discards the packet and sends an ICMP Parameter Problem message back to the source.

Ron,

Extrapolating as to why you think this is surprising behavior (please correct me if this is wrong), but as I read it, this would be true for any transport protocol and allows the possibility of hosts that don't even know what segment routing is to receive the parameter error. For instance, if someone were just innocently pinging the router's address, which happens also to be an END SID, the source of the ping would get the parameter error. In that case, the host might not even know what segment routing is and much less have any clue why its getting a parameter problem pointing to the nexthdr field for an otherwise simple IPv6 packet.

Tom

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> Am I reading the spec correctly?
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>                                             Ron
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> Juniper Internal
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