[Sidrops] Re: draft-ietf-sidrops-8210bis-23 is ambiguous session mismatch handling

[Ralph Covelli <[e-mail]>]

To be a little more specific,

Routers should be willing to update session IDs after cache resets only 
when it is the response to a protocol negotiation Serial Query.

On 12/20/2025 9:29 PM, Ralph Covelli wrote:
>
> Hi,
>
> It should also be pointed out that this means when a router receives a 
> Cache Reset from an RTR cache they must be willing to update their 
> session ID (from the subsequent Cache Response/EOD).
>
> When a router receives a Cache Reset because the sequence number has 
> fallen out of the cache window this is not the case.
>
> If a router continues to use the old session ID after the Cache Reset, 
> the RTR cache should send an error and terminate the session.
>
> Thanks!
>
> On 12/20/2025 9:05 PM, Ralph Covelli wrote:
>>
>> Or maybe "during the protocol version negotiation" sounds a little 
>> more human. :-)
>>
>> On 12/20/2025 8:54 PM, Ralph Covelli wrote:
>>>
>>> Hello SIDROps!
>>>
>>> Perhaps the following will clear up any possible future confusion:
>>>
>>> 5.3. Serial Query:
>>>     The Session ID tells the cache what instance the router expects to
>>>     ensure that the Serial Numbers are commensurate, i.e., the cache
>>>     session has not been changed.  If the Session ID does not match
>>>     during protocol version negotiation, the cache MUST respond with a
>>>     Cache Reset.
>>>
>>> Thanks!
>>>
>>> On 12/17/2025 1:46 PM, Ralph Covelli wrote:
>>>>
>>>> Hi,
>>>>
>>>> The 5.3 wording was added because of me.  Perhaps it can use a 
>>>> little more tweaking.
>>>>
>>>> Both Reset Queries and Serial Queries can be the first command issued.
>>>>
>>>> When the Serial Query is the *first command issued* and the session 
>>>> ID numbers do not match the RTR cache, then the RTR cache should 
>>>> send a Cache Reset.
>>>>
>>>> If a later Serial Query is issued and the session ID number somehow 
>>>> changes the RTR cache must terminate the session.
>>>>
>>>> Thanks!
>>>>
>>>> Ralph Covelli
>>>> Network Engineer
>>>> Hurricane Electric / AS6939
>>>> On 12/17/2025 8:38 AM, Marco Marzetti wrote:
>>>>> Dear members of the SIDROPS WG,
>>>>>
>>>>> I am working on a Python implementation of a RTR Cache, and I 
>>>>> noticed some ambiguity around how session mismatch should be handled.
>>>>>
>>>>> At 5.1. (Fields of a PDU) the draft states that:
>>>>>       If, at any time after the
>>>>>       protocol version has been negotiated (Section 7), either the
>>>>>       router or the cache finds that the value of the Session ID 
>>>>> is not
>>>>>       the same as the other's, the party which detects the 
>>>>> mismatch MUST
>>>>>       immediately terminate the session with an Error Report PDU with
>>>>>       code 0 ("Corrupt Data"), and the router MUST flush all data
>>>>>       learned from that cache.
>>>>>
>>>>> While at 5.3. (Serial Query), the it states:
>>>>>    The Session ID tells the cache what instance the router expects to
>>>>>    ensure that the Serial Numbers are commensurate, i.e., the cache
>>>>>    session has not been changed.  If the Session ID does not 
>>>>> match, the
>>>>>    cache MUST respond with a Cache Reset.
>>>>>
>>>>>
>>>>> Does that mean that the Cache should send the Error Report PDU in 
>>>>> all cases but not in response to a Serial Query?
>>>>>
>>>>> Thanks
>>>>>
>>>>> -- 
>>>>> Marco
>>>>>
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