Re: [Isis-wg] Simplified Extension of LSP Space for IS-IS Draft

[Hannes Gredler <hannes at juniper.net>]

les,

i have read through your draft and do think that there may
be a simpler fix to all of the fragment scalability problems.

basic idea is to introduce a kind of connector-TLV
where you can link arbitrary information to a diffent sysid
in an additive fashion. unlike the IS ALias TLV it does not
work at the SPF level but rather at the TLV parser level
inside a router which extracts information and adds it
to the internal representation of the LSDB.

---

for example lets assume that a node has two sysids

1921.6800.1001  (main sysid)
1720.1600.1001  (leaf sysid)

in the main LSP we announce all SPF relevant information.

<lsp sysid=1921.6800.1001>
  <area>
  <nlpid>
  <te-id>
  <ip-interface>
  <hostname>
  <extd IS reach>
     <neighbor sysid = xxxx.xxxx.xxxx metric 3000 no-subltv>
  </extd IS reach>
</lsp 1921.6800.1001>

in the leaf LSP we announce all non-SPF relevant information

<lsp sysid=1720.1600.1001>
  <connector sysid=1921.6800.1001>
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  <extd IS reach>
     <neighbor sysid=xxxx.xxxx.xxxx metric 0>
       <unreserved bandwidth>
  </extd IS reach>

  /* occurence of a connector TLV links all TLV / subTLV
     information found in that fragment in an additive fashion.
     so we may repeat the extd-IS reach attribute with different subTLV content.
   */

  <extd IS reach>
     <neighbor sysid=xxxx.xxxx.xxxx metric 0>
       <interface-address>
       <neighbor-address>
       <unreserved bandwidth>
  </extd IS reach>

</lsp 1720.1600.1001>

a receiving router should add all information found in a fragment
containing the connector TLV in an additive fashion upon installation in the
local representation of the LSDB. for subTLV information the higher-level
TLV information serves as key. (in our example sysid is the key for any subTLVs
linked)

what needs to be taken care is security/purging related stuff if some external node
wants to link information.

what do you think ?

/hannes


Les Ginsberg (ginsberg) wrote:
> Folks -
>
> The draft describing the alternative to RFC 3786 is now available.
>
> http://www.ietf.org/internet-drafts/draft-ginsberg-isis-extlsp-00.txt
>
>    Les

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