Hi Les,
Thanks much for your comments.
My responses are inline below with HC.
Best Regards,
Huaimo
________________________________
From: Les Ginsberg (ginsberg) <[email protected]>
Sent: Thursday, March 23, 2023 3:35 AM
To: [email protected] <[email protected]>; [email protected]
<[email protected]>
Subject: Comments on draft-chen-lsr-isis-big-tlv-00
Folks -
This draft proposes a new way to handle advertisement of more than 255 bytes of
information about a given object.
It defines a new "container TLV" to carry additional information about an
object beyond the (up to) 255 bytes of information advertised in an existing
TLV.
The draft is defining a solution to a problem which has already been addressed
without requiring any protocol extensions.
[HC]: It seems that a protocol includes a set of procedures. Would you mind
telling me which existing protocols can be used to resolve the problem without
requiring any protocol extensions?
The existing solution - discussed in
https://datatracker.ietf.org/doc/draft-pkaneria-lsr-multi-tlv/<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdatatracker.ietf.org%2Fdoc%2Fdraft-pkaneria-lsr-multi-tlv%2F&data=05%7C01%7Chuaimo.chen%40futurewei.com%7C6e9af0fb3bcd4bef57a408db2b7125a4%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C638151537195561122%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=23RCLltpVh%2BmKSaVzz6v%2FprNKtUU%2Bqx0FEik6x7qvHs%3D&reserved=0>
has already been successfully implemented and deployed by multiple vendors.
[HC]: You are a co-author of this draft, called a first draft for resolving the
problem on big TLVs. This first draft contains some protocol extensions. If
there is a solution for the problem without requiring any protocol extensions,
then why do you as a co-author work on the first draft with protocol extensions?
The definition of a second solution to the problem is not needed - and in fact
further complicates both implementation and deployment. Should the existing
solution be used? Should the new solution be used? What is the state of support
by all nodes in the network for each solution?
[HC]: It seems better to merge the two drafts (i.e., the first draft and the
second draft defining container TLV) into one.
The motivation for the new solution seems to be the notion that it supports
partial deployment. Text in
https://www.ietf.org/archive/id/draft-chen-lsr-isis-big-tlv-00.html#name-incremental-deployment<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.ietf.org%2Farchive%2Fid%2Fdraft-chen-lsr-isis-big-tlv-00.html%23name-incremental-deployment&data=05%7C01%7Chuaimo.chen%40futurewei.com%7C6e9af0fb3bcd4bef57a408db2b7125a4%7C0fee8ff2a3b240189c753a1d5591fedc%7C1%7C0%7C638151537195561122%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=AwI4YHL1uPDwbqPoCtjvobS424RT3OGNWdUxM9XclUY%3D&reserved=0>
states:
"For a network using IS-IS, users can deploy the extension for big TLV in a
part of the network step by step.
The network has some nodes supporting the extension (or say new nodes for
short) and the other nodes not
supporting the extension (or say old nodes for short) before the extension is
deployed in the entire network."
This suggests the authors believe that a network can function with some nodes
using all of the advertisements and some nodes using only the legacy
advertisements, but this is obviously false.
Fundamental to operation of a link state protocol is that all nodes in the
network operate on identical LSPDBs.
The suggestion that features will work correctly when some nodes use attributes
advertised in legacy TLVs and the new container TLV while some nodes use only
the attributes advertised in legacy TLVs is simply incorrect.
[HC]: Every node in the network has the same LSPDB. The new nodes understand
the new container TLVs and may use them. The old nodes do not understand them
and do not use them.
It is also important to also state that the advertisement of more than 255
bytes of information is driven by configuration – not a protocol implementation
choice. Suppressing advertisement of some of the configured information also
does not result in a working network.
In short, there is no positive value from the proposed extension – and it does
harm by further complicating implementations and deployments.
[HC]: The second draft defines a general mechanism for resolving the problem.
It is backward compatible and simple. It does not do any harm.
The draft should be abandoned.
Les
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