Telechat Review of draft-ietf-isis-l2bundles-04
review-ietf-isis-l2bundles-04-opsdir-telechat-jethanandani-2017-04-20-00

Request Review of draft-ietf-isis-l2bundles
Requested rev. no specific revision (document currently at 07)
Type Telechat Review
Team Ops Directorate (opsdir)
Deadline 2017-04-25
Requested 2017-04-06
Other Reviews
Review State Completed
Reviewer Mahesh Jethanandani
Review review-ietf-isis-l2bundles-04-opsdir-telechat-jethanandani-2017-04-20
Posted at https://mailarchive.ietf.org/arch/msg/ops-dir/srPFOvncjpuI9tD8sm3dd0wQ14M
Reviewed rev. 04 (document currently at 07)
Review result Has Issues
Last updated 2017-04-20

Review
review-ietf-isis-l2bundles-04-opsdir-telechat-jethanandani-2017-04-20

I have reviewed this document as part of the Operational directorate’s ongoing effort to review all IETF documents being processed by the IESG.  These comments were written with the intent of improving the operational aspects of the IETF drafts. Comments that are not addressed in last call may be
included in AD reviews during the IESG review.  Document editors and WG chairs should treat these comments just like any other last call comments.

Document reviewed:  draft-ietf-isis-l2bundles-04

Summary: 

There are deployments where the Layer 3 interface on which IS-IS operates is a Layer 2 interface bundle.  Existing IS-IS advertisements only support advertising link attributes of the Layer 3 interface. If entities external to IS-IS wish to control traffic flows on the individual physical links which comprise the Layer 2 interface bundle link attribute information about the bundle members is required.

Document Status:

Has Issues

Comments:

The following comments look at the document both from an operational perspective as well as a management perspective. 

Operational Considerations:

Operational considerations include installation and initial setup, migration path, requirements on other protocols, impact on network operations and verification of correct operation.

Advertisement of these link attributes needs to be configured, including which attributes will be advertised. While there are some attributes, e.g. max link bandwidth, which can be learnt and advertised, there are others that need configuration. What is not clear from the draft is which of the attributes should be configured as  a minimum, and if they can have default values that they can carry.

Since these are TLVs, it is assumed that the controller that does not understand the advertisement will ignore the TLV. From a network operations perspective, there will be more of these advertisements that need to be sent, and will have to tracked and maintained by the controller.

Whether these advertisements result in a correct operation is not obvious, because there is no feedback mechanism on how these advertisements are being used, other than watching the changes that happen from a TE perspective.

Management Considerations:

Management considerations include interoperability, fault management, configuration management, accounting, performance and security.

The attributes being advertised are additional to existing link attributes. In that sense, it is new and additional information, as does not impact existing operations. Controllers that understand the new advertisements will use them, and those that do not, will ignore them. Interoperability therefore, should not be impacted.

However, there is no discussion of fault management. For example, if one of the links in the bundle goes down, are the attribute values updated to reflect the new state of the bundle. There is also no definition of how these attributes are configured on the box. Ideally, we should see a YANG model defining the new attributes that can be configured for advertisement.

As discussed above, there is no accounting for how these new advertisements are being used, or whether they are being used by the controller at all. Updates to TE as a result of these advertisements should be accounted to indicate the effectiveness of the new advertisements.

Performance should not be an issue, as these are advertisements, even if they take up a small amount of additional bandwidth for advertisement.

Finally, and importantly, the draft needs to address the question of security, even if it means pointing to a boiler plate set of drafts that deal with similar issues. It would be hard to believe that there are no security considerations to be had.

A run of idnits revealed no errors, flaws, or warnings. There were 3 comments though

     (See RFCs 3967 and 4897 for information about using normative references
     to lower-maturity documents in RFCs)

  -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE802.1AX'

  -- Possible downref: Non-RFC (?) normative reference: ref. 'ISO10589'


     Summary: 0 errors (**), 0 flaws (~~), 0 warnings (==), 3 comments (--).