Re: [Lsr] LSR Working Group Adoption Call for "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01

[Huaimo Chen <[e-mail]>]

Support and have the following comments:


  1.  It seems not necessary to have 8 levels of hierarchies. 3 or at most 4 levels of hierarchies should be enough. IS-IS with 3 levels of hierarchies may support a network with 1k*1k*1k nodes, which is about 10^9 = 1 billion nodes. IS-IS with 4 levels of hierarchies may support a network with 1k*1k*1k*1k nodes, which is about 10^12 = 1 trillion nodes.
  2.  For PDU type, section 2.2 of the draft proposes to use 8 bits (all three reserved bits plus the 5 bits for the existing PDU type). It seems better to use 6 bits (one reserved bit plus the 5 bits for the existing PDU type). Adding one reserved bit into the PDU Type allows people to define 32 new PDU types, which is enough for the new PDU types needed for new hierarchies.
  3.  Section 3 “Additional PDUs” of the draft, defines 6 new PDU Types for ’Level n LAN IS to IS hello PDU’ (Ln-LAN-HELLO-PDU), where n is 3, 4, 5, 6, 7, and 8. In addition, the following new PDU Types should be defined (considering at most 4 levels of hierarchies):
     *   2 new PDU Types for ‘’Level n LSP”, where n is 3, and 4
     *   2 new PDU Types for ‘’Level n CSNP”, where n is 3, and 4
     *   2 new PDU Types for ‘’Level n PSNP”, where n is 3, and 4
  4.  On a broadcast interface, Level 1 LSPs are multicast through MAC 0x0180.c200.0014 (which is called AllL1ISs), and Level 2 LSPs are multicast through MAC 0x0180.c200.0015 (which is called AllL2ISs). It seems that Level n LSPs should be multicast through AllLnISs, where n is 3, and 4 (considering at most 4 levels of hierarchies), thus
     *   2 new MAC should be assigned to AllLnISs, where n is 3, and 4.
  5.  The existing DIS for a broadcast interface periodically multicast through AllL1ISs and AllL2ISs a Complete SNP (CSNP). It seems that the DIS should be extended to periodically multicast a CSNP through AllLnISs, where n is 1, 2, 3, and 4 (considering at most 4 levels of hierarchies).
  6.  When there may be 3 or more levels of hierarchies, is it allowed to have 3 or more levels (consecutive) configured on an interface? It seems that there is no description about this in the draft.

Best Regards,
Huaimo

From: Lsr <[e-mail]> On Behalf Of Acee Lindem (acee)
Sent: Monday, August 12, 2019 10:33 AM
To: [e-mail]
Subject: [Lsr] LSR Working Group Adoption Call for "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01

This begins a two week LSR Working Group Adoption Poll for the "Hierarchical IS-IS" - draft-li-lsr-isis-hierarchical-isis-01. The poll will end at 12:00 AM UTC on August 27th, 2019. Please indicate your support of objection on this list prior to the end of the adoption poll.

Thanks,
Acee