Yongqing,

I have two basic comments:

1. Using L2 Bundle Member Attributes TLV for advertising attributes for VTNs seems like a hack.

2.

  "In order to correlate the virtual or physical member links with the
   corresponding VTNs, each member link SHOULD be assigned with a
   dedicated Admin Group or Extended Admin Group, which is included in
   the definition of the Flex-Algo of the corresponding VTN.  Note that
   in this case the Admin Group or Extended Admin Group of the Layer 3
   link SHOULD be set to the union of all the Admin Groups or Extended
   Admin Groups of its virtual or physical member links.  This is to
   ensure that the Layer 3 link is always included in the Flex-Algo
   specific constraint path computation of the VTNs it participates in."

Above proposal does not work. Here's the simple example:

Flex-algo 128, FAD include RED
Flex-algo 129, FAD exclude RED

Now you have two VTNs, one for FA 128 (VT1) and one for 129 (VT2).

So your VT1 member link will have affinity RED and your VT2 will not have any affinity set (I presume).

Your L3 will have affinity RED set based on your proposal. As a result the L3 link will be be excluded for FA 129, but that is not what you want, because your VTN2 does not have affinity RED set.

The fundamental problem is that FA works on L3 data only. You are trying to make it work for L2, but that is not going to work.

thanks,
Peter


On 16/09/2020 08:13, [email protected] wrote:
Hi WG,

We just submitted a new revision of draft-zhu-lsr-isis-sr-vtn-flexalgo. This 
document specifies a mechanism to use Flex-Algo together with small extensions 
to IS-IS L2 bundle to distribute the topology and resource attribute of SR 
based VTN. Your review and comments are appreciated.
B.R.
Zhu Yongqing

-----邮件原件-----
发件人: [email protected] <[email protected]>
发送时间: 2020年9月11日 17:11
收件人: Dongjie (Jimmy) <[email protected]>; Yongqing Zhu <[email protected]>; 
Huzhibo <[email protected]>
主题: New Version Notification for draft-zhu-lsr-isis-sr-vtn-flexalgo-01.txt


A new version of I-D, draft-zhu-lsr-isis-sr-vtn-flexalgo-01.txt
has been successfully submitted by Jie Dong and posted to the IETF repository.

Name:           draft-zhu-lsr-isis-sr-vtn-flexalgo
Revision:       01
Title:          Using Flex-Algo for Segment Routing based VTN
Document date:  2020-09-11
Group:          Individual Submission
Pages:          8
URL:            
https://www.ietf.org/id/draft-zhu-lsr-isis-sr-vtn-flexalgo-01.txt
Status:         
https://datatracker.ietf.org/doc/draft-zhu-lsr-isis-sr-vtn-flexalgo/
Htmlized:       
https://datatracker.ietf.org/doc/html/draft-zhu-lsr-isis-sr-vtn-flexalgo
Htmlized:       
https://tools.ietf.org/html/draft-zhu-lsr-isis-sr-vtn-flexalgo-01
Diff:           
https://www.ietf.org/rfcdiff?url2=draft-zhu-lsr-isis-sr-vtn-flexalgo-01

Abstract:
    As defined in I-D.ietf-teas-enhanced-vpn, enhanced VPN (VPN+) aims to
    provide enhanced VPN service to support the needs of enhanced
    isolation and stringent performance requirements.  VPN+ requires
    integration between the overlay VPN and the underlay network.  A
    Virtual Transport Network (VTN) is a virtual network which consists
    of a subset of network topology and network resources allocated from
    the underlay network.  A VTN could be used as the underlay for one or
    a group of VPN+ services.

    I-D.dong-lsr-sr-enhanced-vpn defines the IGP mechanisms with
    necessary extensions to build a set of Segment Routing (SR) based
    VTNs.  This document describes a simplified mechanism to build the SR
    based VTNs using SR Flex-Algo together with minor extensions to IGP
    L2 bundle.





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