To: ITU-T Q14/15
From: IETF CCAMP Working Group
Cc: Stephen Trowbridge, Kam Lam, Scott Bradner, Dave Ward, Ross Callon, CCAMP Working Group
Subject: ASON Routing Loop Prevention
For Action
The IETF's CCAMP Working Group thanks you for your liaison entitled "Liaison Statement to CCAMP on ASON Routing Loop Prevention" issued from your Stuttgart interim meeting in September 2007.
Your understanding is correct, the Associated Area ID reflects the area from which the routing information is received. For your example, it would reflect C, not D. As the description in Section 6.3.1 of our draft was misunderstood, we will add clarifications.
Thank you for flagging your concerns about reconfiguration scenarios. As you say in your liaison, the frequency of reconfigurations that require the change of Area ID is unlikely to be high, but we recognize the importance of making sure such procedures can be followed without unduly opening up scope for operator error and without causing excessive configuration activity. In this respect, we have been guided by the reorganization requirements set out in RFC 4258 and the evaluation scenarios described in RFC 4652. As described in 6.3 of the draft, the use of the Associated Area ID is only required in scenarios when more than one RC is bound to an adjacent level of the hierarchy and both are configured to redistribute routing information. As the operational aspects remain a concern to you, we will add text to the draft to further clarify aspects of OSPF operations for reorganization scenarios.
Please let us know of any remaining operational concerns.
Best regards,
Adrian Farrel and Deborah Brungard
IETF CCAMP Working Group Co-Chairs