Re: END SID Without SRH

[Bob Hinden <[e-mail]>]

Darren,

> On Jun 12, 2019, at 5:57 PM, Darren Dukes (ddukes) <[e-mail]> wrote:
> 
> Hi Bob. See inline. 
> 
> On Jun 13, 2019, at 1:04 AM, Bob Hinden <[e-mail]> wrote:
> 
>> Darren,
>> 
>>> On Jun 12, 2019, at 2:52 PM, Darren Dukes (ddukes) <[e-mail]> wrote:
>>> 
>>> Hello everyone.
>>> 
>>> This document defines an SRH and a SID, and how that SID is processed.
>>> 
>>> I expect anyone "surprised" by this fact should have read this draft at some point:
>>> a - within the past 2 years; since this document has defined a SID and its processing.
>>> b - within the past 13 months; since section 4.3.1 specifically described discarding the packet based on upper layer header being processed.
>>> c - within the past 8 months; since the current version of 4.3.1.2 was updated with the new ICMP error code, published, and the WG was notified via email.
>>> 
>>> And recall section 3.1 defines a Source SR node as 
>>>  "any node that originates an IPv6 packet with a
>>>  segment (i.e.  SRv6 SID) in the destination address of the IPv6
>>>  header.  The packet leaving the source SR Node may or may not contain
>>>  an SRH."
>>> 
>>> In other words, there is no surprise.
>> 
>> I am trying to sort out this discussion. 
>> 
>> I think the text in the draft this discussion is about is:
>> 
>>> 4.3.1.2.  Upper-layer Header or No Next Header
>>> 
>>>   When processing the Upper-layer header of a packet matching a FIB
>>>   entry locally instantiated as an SRv6 SID defined in this document.
>>> 
>>>   IF (Upper-layer Header is IPv4 or IPv6) and
>>>       local configuration permits {
>>>     Perform IPv6 decapsulation
>>>     Resubmit the decapsulated packet to the IPv4 or IPv6 module
>>>   }
>>>   ELSE {
>>>     Send an ICMP parameter problem message to the Source Address and
>>>     discard the packet.  Error code (TBD by IANA) "SR Upper-layer
>>>     Header Error", pointer set to the offset of the upper-layer
>>>     header.
>>>   }
>>> 
>>>   A unique error code allows an SR Source node to recognize an error in
>>>   SID processing at an endpoint.
>> 
>> 
>> If I understand it correctly, the case for the action described in this section  is:
>> 
>>   When processing the Upper-layer header of a packet matching a FIB
>>   entry locally instantiated as an SRv6 SID defined in this document.
>> 
>> A node receiving this packet that knows it is SRv6 SID (because it was locally instantiated), would follow this procedure.   
> 
> Correct. 
> 
>> A node who does not know that it is an SRv6 SID, will process the packet normally as defined in RFC8200/etc/etc.
>> 
> 
> Yes. This case is covered by section by 4.3.3 specifically, where the destination lpm matches a non-local Route.
> 
> 
> 4.3.3. FIB Entry Is A Non-Local Route
> 
> Processing is not changed by this document.
> 
>> Essentially, a node will only do this if it is in an SRv6 domain because it has had SRv6 SID information configured manually or via some protocol.
>> 
>> Am I correct?
> 
> Yes you are correct. 
> 

Thanks.   I don’t see any issue here, the document is appropriately scoped.

Bob