Re: [OSPF] regarding draft-ppsenak-ospf-te-link-attr-reuse-00

"Acee Lindem (acee)" <> Thu, 07 January 2016 12:16 UTC

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From: "Acee Lindem (acee)" <>
To: "xuling (F)" <>, "" <>
Thread-Topic: [OSPF] regarding draft-ppsenak-ospf-te-link-attr-reuse-00
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Subject: Re: [OSPF] regarding draft-ppsenak-ospf-te-link-attr-reuse-00
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Hi Ling,

From: OSPF <<>> on behalf of "xuling (F)" <<>>
Date: Wednesday, January 6, 2016 at 9:52 PM
To: OSPF WG List <<>>
Subject: [OSPF] regarding draft-ppsenak-ospf-te-link-attr-reuse-00

Hi Acee,

I suggest to advertise SRLG only in the TE opaque LSA, and advertise TE capability to help understand whether node is TE enabled. If node isn’t TE enabled , SRLG shouldn’t be used for TE application; otherwise, SRLG can be used for TE application or for other application purposes.

I don’t think this is a good idea since it doesn’t solve of the problem of consolidating non-TE information in the OSPF prefix/link attribute LSA and avoiding having to advertise and process three independent LSAs. Also, if you are going to require a protocol change anyway, you might as well use the OSPF prefix/link LSAs.


the mechanism to advertise TE capability has been well defined in draft-ietf-ospf-rfc4970bis.

Best regards,

Hi Ling,

From: OSPF <<<>>> on behalf of "xuling (F)" <<<>>>

Date: Wednesday, January 6, 2016 at 2:28 AM

To: OSPF WG List <<<>>>

Subject: [OSPF] regarding draft-ppsenak-ospf-te-link-attr-reuse-00

Hi, all

To make the node that is not TE enabled advertises link attributes for other applications, it is worth considering another choice which has least change to the protocol and implementation. The method is: advertising RI capability TLV in RI LSA when advertising TE LSA. TE capability bit in RI capability TLV can indicate whether link attributes should become part of TE topology.

In draft-ietf-ospf-rfc4970bis,

?an OSPF router advertising an OSPF RI LSA MAY include the Router Informational Capability TLV?? can be enhanced with: an OSPF router advertising an OSPF RI LSA should include Router Informational Capability TLV which can inform TE capability bit.

In this case, some improvement needs to be done in draft-ietf-ospf-rfc4970bis. These are my personal view.

The intent of RFC 4970 and the BIS version is that the drafts requiring new capabilities will define them and request IANA allocation as opposed to updating RFC 4970BIS for every new capability.

As for the mechanism, I think this would be rather unwieldy to attempt to get SRLG information from different LSAs. Rather, within the OSPF Routing Domain, I?d choose to advertise SRLGs either in the TE LSAs or the Prefix/Link Attribute LSAs.



Best regards,

Ling XU

华为技术有限公司 Huawei Technologies Co., Ltd.

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