Subject: RE: [NSIS] qos-nslp-00

From: "McDonald, Andrew" <[email-masked]>
Date: Fri, 24 Oct 2003 15:49:43 +0100

Hi Rüdiger,

I wrote:
> Geib, Ruediger wrote:
>> thanks, your example explains two things I couldn't find in the
>> draft: 
>> - that session IDs still need to be present and aren't replaced   by
>> RSNs. 
>> - how QoS-NSLP could react once it notes that it maintains stale
>>   state.
> 
> Ok. Clearly we'll need some updates in those areas.

So, here they are. My suggested updates to provide clarification on these
points:

Change last paragraph on page 13 (section 3.1):
... A RSN is an identifier that indicates the order in which state
modifying actions are performed by a QNE. ...
to:
... An RSN is an incrementing sequence number that indicates the order
in which state modifying actions are performed by a QNE. ...

Section 4.2, add a new last paragraph:
When a QNE receives a partial refresh message it compares the RSN
against that of the currently installed reservation. If it matches
then the state is refreshed. If the RSN in the message is less than
that of the currently installed state (i.e. it refers to 'old' state)
then the message is discarded (possibly the messages got reordered
between the nodes). If the RSN in the message is greater than that of
the currently installed state then an error MUST be signalled back. It
means that the peer QNE believes that state is installed when it is
not. If not informed it would continue to attempt to refresh the
non-existent state. A partial refresh containing either an unknown
session identifier or flow identifier MUST also be responded to with
an error message (this is likely to occur following a rerouting
event).

Section 3.1, insert new paragraph before final one:
A Flow Identifier groups together state items for a single flow. The
RSN is one of these state items, and is used to identify reordering of
messages and to allow the use of partial refresh messages. The state
items for a number of flows can be linked together and identified as
part of a single reservation using a Session Identifier. The
identifiers play complementary roles in the management of QoS NSLP
state.

[NB: this is slightly different from what I said before - my previous
e-mail ignored the issue that flow identifiers can change in a given
session.]

Andrew
-- 
Andrew McDonald
Roke Manor Research Ltd, Romsey, Hants  SO51 0ZN
Phone +44 1794 833833   Fax +44 1794 833434

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