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[Lsr] Is it necessary to expand the IS-IS level to 8?

"Aijun Wang" <wangaijun@tsinghua.org.cn> Mon, 06 January 2020 04:03 UTC

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From: Aijun Wang <wangaijun@tsinghua.org.cn>
To: lsr@ietf.org
Date: Mon, 06 Jan 2020 12:02:48 +0800
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Subject: [Lsr] Is it necessary to expand the IS-IS level to 8?
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Hi, Tony, Les and Paul: 

 

As I read the draft
https://tools.ietf.org/html/draft-ietf-lsr-isis-extended-hierarchy-00, and
notice the proposal to expand the reserved bits in "Circuit Type" to cover
the level 1-8 in ISIS domain.

Here I just want to know is it necessary to expand the IS-IS level to 8 and
occupy all the reserved bits in the PDU format?

 

As compared with the OSPF format, there is one field to describe the "Link
Type" (5 bits, currently define only four types). We want to use the
reserved bits in current "Circuit Type" of ISIS PDU format to fulfill the
similar tasks. 

 

Can this draft leave at least 2 reserved bits for this purpose? There are
many ways to tackle the scale of networks, who will design their network in
level 8 hierarchy? As I estimated, Level 4 may be the acceptable highest
network hierarchy.

 

 

Best Regards.

 

Aijun Wang

China Telecom

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