Transcript (IS-IS) draft-li-isis-degradation-isolation-problem-00

Problem Statement: Link Degradation Isolation in
Interoperable Networks
using Intermediate System to Intermediate System
(IS-IS)
draft-li-isis-degradation-isolation-problem-00
Zhenqiang Li
Lianyuan Li
Xiaodong Duan
July 2008
Standard Definition
• Section 7.3.14.2 in ISO 8473 states: An
Intermediate System receiving a LSP with
an incorrect LSP Checksum or with an
invalid PDU syntax shall
– generate a corruptedLSPReceived circuit
event
– discard the PDU
Problem
• Sometimes because of network error, such
as the deterioration of transmission quality,
the checksum is error
– the network error can not be isolated
automatically
– The error ratio of IP packets increases
Problem (cont.)
• The implementation of certain vendor does
not comply with ISO 8473
– Not generate the corruptedLSPReceived
circuit event when it receives the corrupted
LSP,
– the corruptedLSPReceived circuit event is
not reported to the network management
system
Suggestion
• When the router discards the corrupted
LSP, it SHOULD inform the corresponding
router(s) in its neighbor by some way and
the neighbor router(s) check the state of
the corresponding link
– Consideration on BFD
• BFD is not used with IS-IS at any time
• BFD doesn’t work well for network deterioration
Suggest (Cont.)
• All the implementation of IS-IS protocol
SHOULD firmly comply with the ISO
10589 Recommendation.
– A corruptedLSPReceived circuit event MUST
be generated and SHOULD be reported to the
network management system, when network
device receives a LSP with an incorrect LSP
checksum.
Next Steps
• The authors would like to request more
WG feedbacks