Re: [spring] Alvaro Retana's Discuss on draft-ietf-spring-srv6-network-programming-20: (with DISCUSS and COMMENT)

["Joel M. Halpern" <[e-mail]>]

Alvaro, at this point as document shepherd I have to ask if these are 
still discuss level concerns?

Yours,
Joel

On 10/7/2020 11:04 AM, Alvaro Retana wrote:
> On September 30, 2020 at 9:18:37 AM, Pablo Camarillo wrote:
> 
> 
> Pablo:
> 
> Hi!
> 
> Just leaving below the points I still want to talk about.
> 
> Thanks!
> 
> Alvaro.
> 
> 
> ...
>>> ----------------------------------------------------------------------
>>> DISCUSS:
>>> ----------------------------------------------------------------------
> ...
>>> (1b) It would be nice if the behavior in §4.1.1 were also specified
>>> using pseudocode...
> ...
>> §4.1.1 is called from different places, while processing different
>> behaviors. Is it expected that the "local configuration" will cover each
>> behavior individually, or will the operator be able to configure a single
>> policy for all? In either case, it would be good to mention it.
>>
> [PC2] In the document we've left 'local configuration' up to an
> [PC2] implementation. Whether an implementation implements the local
> [PC2] configuration on an interface as an ACL or globally for all SIDs or per
> [PC2] SID via some API is not for this document to decide, and has no impact
> [PC2] on interoperability.
> 
> True, it has no impact on interoperability, but it can have an impact
> on the operation of the network.  While not including details about
> local configuration, I would like to see some guidance on the
> definition of proper policies.  For example, considering your example
> of allowing ICMPv6, OAM may be important, but forwarding a packet that
> is not in line with the behavior would not be.
> 
> Along those lines, the headend policy should be consistent with the
> behavior and any local configuration.  This expectation should also be
> mentioned somewhere.
> 
> 
> ...
>>> (3) The description of the flavors in §4.16 is also unclear.
>> ...
>> For an endpoint behavior that indicates more than one flavor, which one
>> should be applied?
>>
>> For some of the behaviors, 29 (End with PSP&USD) for example, the flavor
>> used seems to depend on the number of SLs: if received with SL == 0, then
>> the flavor is USD, but if received with SL == 1 then use PSP. But for other
>> behaviors, 30 (End with USP&USD) for example, which flavor should be applied
>> if both are supported?
>>
> [PC2] When a behavior (e.g. End) is combined with one or more flavors (e.g.
> [PC2] USP & USD), their combined pseudocode is what determines the packet
> [PC2] processing. In the specific example of USP&USD (when SL=0), the
> [PC2] pseudocode would end up first removing the processed SRH and then,
> [PC2] depending on the next upper-layer header, also removing the outer IPv6
> [PC2] encapsulation header if/when there is an inner IP packet.
> 
> Oh, it's the combination; that is not mentioned anywhere.
>