配色参考方案：以下为三组配色方案。（仅供参考）

Recommendations for LSP Checksum Calculation and Related Processing in

Multi-vendor Networks using IS-IS

Zhenqiang Li @ China Mobile77th IETF @ Anaheim

March 2010

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Content

PurposeRecommendations

Checksum CalculationZero Checksum LSP ProcessingZero Remaining Lifetime LSP ProcessingCorrupt LSP Processing

Next steps

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Purpose

To show the observations found in China Mobile’s network, consisting of hundreds of routers from several vendors.To make the IS-IS enabled routers work more robustly and interoperably. To make the IS-IS protocol itself more fault-tolerative, especially in a multi-vendor network environment.

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Checksum Calculation

To calculate the checksum of all LSPs correctly, including zero Remaining Lifetime LSP, although examining the checksum of a zero Remaining Lifetime LSP should always be successful.Based on the specification, the checksum of a zero Remaining Lifetime LSP can be any value. In practice, some implementations fill the checksum with zero.If router A does not generate correct checksum for zero Remaining Lifetime LSP and sends the LSP to router B, router B checks the LSP and discards it due to incorrect checksum. Router B should upgrade its implementation according to the IS-IS specification. However, if router A correctly calculates checksums of all LSPs, it can work with router B. And there will be no problem in a network consisting of such routers.

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Zero Checksum LSP Processing

In practice, some implementations check the checksum first, then the remaining lifetime.

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Zero Remaining Lifetime LSP Processing

Do not check the checksum of Zero Remaining Lifetime LSP. Zero Remaining Lifetime LSPs SHOULD always pass the check.

Although this was specified in ISO 10589 in 2002, we still found wrong implementations of routers in China Mobile’s network in 2007.This point was not emphasized in RFC3719. It is useful to point it out in this draft both for the vendors and for the operators.

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Corrupt LSP Processing

Router receiving corrupt LSP shallgenerate a corruptedLSPReceived circuit eventdiscard the PDU

If switch to control the the processing mechanism is provided, the default state of such switch SHOULD be in accordance with the correct behavior specified in the standards.

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Next steps

Any comments are welcome.Move this draft forward to be a working group draft?

配色参考方案：以下为三组配色方案。（仅供参考）

Thank You !!

中国移动通信研究院CHINA MOBILE RESEARCH

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