Hi Jie,
On 16/09/2020 12:02, Dongjie (Jimmy) wrote:
Hi Peter,
Thanks for your comment. Please see some replies inline:
-----Original Message-----
From: Lsr [mailto:[email protected]] On Behalf Of Peter Psenak
Sent: Wednesday, September 16, 2020 4:46 PM
To: [email protected]; [email protected]
Subject: Re: [Lsr] 回复: New Version Notification for
draft-zhu-lsr-isis-sr-vtn-flexalgo-01.txt
Yongqing,
I have two basic comments:
1. Using L2 Bundle Member Attributes TLV for advertising attributes for VTNs
seems like a hack.
Yes, the combination of Flex-Algo and L2 bundle can provide the required
functionality of VTN.
L2 Bundle Member Attributes TLV was defined to advertise L2 link bundle
member data, not VTN data. I let others to comment, for me that is not
the right way to encode VTN data.
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).
Maybe the text in draft is not clear enough. Take your example, it should be:
Flex-Algo 128, FAD include RED
Flex-Algo 129, FAD include BLUE
you changed the exclude RED to include BLUE, but I had RED in both FAs,
one include one exclude, that was a valid option with FAD.
If the VTN with FA means that FA can only be based on the single
"affinity include' constraint per FA, please make that clear in the
draft and state that other constraints MUST NOT be used for your
solution to work.
On one L3 link (either a physical L2 bundle or not), the member link for VTN-1
will have affinity RED, the member link for VTN-2 will have affinity BLUE, and
the L3 link SHOULD be set with affinity RED and BLUE (i.e. the union of its
member links).
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.
Based on the affinity of the L3 link (RED and BLUE), the L3 link will be used
for path computation in both FA-128 and FA-129.
Then in forwarding plane, a received packet with prefix-SID of FA-128 will be
steered to use the member link for VTN-1, and a received packet with prefix-SID
of FA-129 will be steered to use the member link for VTN-2. This is the
expected behavior.
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.
The FA based path computation is still based on L3 link attribute, the member
link attribute is used to correlate a subset of link resource with a Flex-Algo,
which can be used for forwarding packet which carries the FA-specific SIDs.
please see my comment above.
thanks,
Peter
Best regards,
Jie
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.
Please note that it may take a couple of minutes from the time of submission
until the htmlized version and diff are available at tools.ietf.org.
The IETF Secretariat
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