Robert –

The need for more than 255 bytes/TLV in this case has nothing to do with 
“non-routing-protocol-data”. It is required because we have a need for more 
than 255 bytes of data directly used by the protocol.

Please do not conflate this with issues related to requests for the IGPs to 
carry data not used by the protocol itself.

   Les

From: Robert Raszuk <[email protected]>
Sent: Friday, November 1, 2024 2:35 AM
To: Les Ginsberg (ginsberg) <[email protected]>
Cc: Henk Smit <[email protected]>; [email protected]; Hannes Gredler 
<[email protected]>
Subject: [Lsr] Re: Using RFC 7356 to address TLV size limitations

Thx Les !

I asked this 2nd time as IMO direction towards growing TLV sizes is not the 
best solution.

Especially for opaque to routing information which applies to (tiny) subset of 
link state nodes in the IGP domain.

See if you keep bringing larger and larger trucks folks will happily keep 
loading stuff (not to say junk) on them.

I would very much prefer that we consider solutions like DROID 
(draft-li-lsr-droid) or any other pub-sub message bus for this type of 
information distribution instead of keep running on existing flooding.

Many thx,
Robert

On Fri, Nov 1, 2024 at 1:28 AM Les Ginsberg (ginsberg) 
<[email protected]<mailto:[email protected]>> wrote:
Robert –

The fact that we have a 16 bit length does not mean we can actually send a 
single TLV of length 65K bytes – nor do we need to do so.

The protocol is still limited by whatever the lsp-mtu in the deployment is – 
which is required to be <= the minimum MTU of all links in the network enabled 
for IS-IS.

References to RFC 5311 are in the context of needing more than 256 
LSPs/node/level – not in the context of 16 bit TLVs.

   Les


From: Robert Raszuk <[email protected]<mailto:[email protected]>>
Sent: Thursday, October 31, 2024 5:16 PM
To: Les Ginsberg (ginsberg) <[email protected]<mailto:[email protected]>>
Cc: Henk Smit <[email protected]<mailto:[email protected]>>; 
[email protected]<mailto:[email protected]>; Hannes Gredler 
<[email protected]<mailto:[email protected]>>
Subject: Re: [Lsr] Using RFC 7356 to address TLV size limitations

Dear Les,


Issue #2 is the limited size of a single TLV/sub-TLV.

This is addressed by using 16 bit type/length fields.

Can you please kindly elaborate how you fit 65K octet TLV into 9K octets of 
jumbo frames (max practical MTU) on a link used for flooding between any two 
nodes ?

RFC7356 says go and read RFC5311 on how to do that. Well can you pls point me 
to a section of RFC5311 which explains how to do it? My reading of it leads me 
to believe that it very well describes how to get around the 256 LSP limit. But 
not how to fit an elephant into a rope bridge.

Thx,
Robert
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