I am the assigned Gen-ART reviewer for this draft. For background on
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Document: draft-ietf-mpls-p2mp-lsp-ping-16
Reviewer: Alexey Melnikov
Review Date:2011-05-31
IETF LC End Date: 2011-05-30
IESG Telechat date:
Summary: This draft is almost ready for publication as a standard track
RFC. There are some minor clarity issues (or reviewer confusions) that
are worth clarifying.
Major issues: none
Minor issues:
1.1. Design Considerations
As is described in [RFC4379], to avoid potential Denial of Service
attacks, it is RECOMMENDED to regulate the LSP Ping traffic passed to
the control plane. A rate limiter should be applied to the
well-known UDP port defined for use by LSP Ping traffic.
What is this port? Is mentioning of the port significant?
3.1.2.1. Multicast LDP FEC Stack Sub-TLVs
Address Family
Two octet quantity containing a value from ADDRESS FAMILY NUMBERS
in [IANA-PORT] that encodes the address family for the Root LSR
Address.
[IANA-PORT] IANA Assigned Port Numbers, http://www.iana.org
Which IANA registry do you have in mind? Seeing a link would be helpful.
3.2. Limiting the Scope of Responses
The P2MP Responder Identifier TLV only has meaning on an echo request
message. If present on an echo response message, it SHOULD be
ignored.
Are there known reasons for violating the SHOULD? I.e. what are the reasons
for having multiple sub-TLVs in the first place?
3.2.2. Node Address P2MP Responder Identifier Sub-TLVs
The address in this Sub-TLV SHOULD be of any transit, branch, bud or
egress node for that P2MP LSP.
Is the use of SHOULD correct here (instead of a MUST)? Are there any choices
left if the SHOULD is violated?
3.5. Downstream Detailed Mapping TLV
Downstream Detailed Mapping TLV is described in [DDMT]. A transit,
branch or bud node can use the Downstream Detailed Mapping TLV to
return multiple Return Codes for different downstream paths. This
functionality can not be achieved via the Downstream Mapping TLV.
Are "Downstream Detailed Mapping TLV" and "Downstream Mapping TLV" two
different things?
As
per Section 4.3 of [DDMT], the Downstream Mapping TLV as described in
[RFC4379] is being deprecated.
4.1.2. Jittered Responses to Echo Requests
Echo response jittering SHOULD be used for P2MP LSPs. If the Echo
Jitter TLV is present in an echo request for any other type of LSPs,
the responding egress MAY apply the jitter behavior as described
here.
Can you provide a bit more information about how this work?
4.2.1.1. Responses from Transit and Branch Nodes
The presence of a Downstream Detailed Mapping TLV will influence the
choice of Return Code. As per [DDMT], the Return Code in the echo
response header MAY be set to value TBD ('See DDM TLV for Return Code
Am I correct that the value TBD is specified in [DDMT]?
If not, it is missing in the IANA Considerations section.
and Return SubCode') as defined in [DDMT]. The Return Code for each
Downstream Detailed Mapping TLV will depend on the downstream path as
described in [DDMT].
6. OAM and Management Considerations
- A MIB module is required for the control and management of LSP
Ping operations, and to enable the reported information to be
inspected.
I think it would be better to be explicit that this document doesn't
define such a MIB.
7.2. New TLVs
P2MP Responder Identifier TLV (see Section 3.2) is a mandatory
What does "mandatory" means in this section? Mandatory for IANA?
TLV. Suggested value 11.
Four sub-TLVs are defined.
- Type 1: IPv4 Egress Address P2MP Responder Identifier
- Type 2: IPv6 Egress Address P2MP Responder Identifier
- Type 3: IPv4 Node Address P2MP Responder Identifier
- Type 4: IPv6 Node Address P2MP Responder Identifier
Echo Jitter TLV (see Section 3.3) is a mandatory TLV. Suggested
As above.
value 12.
Nits/editorial comments:
4.3.1. End of Processing for Traceroutes
For P2MP TE LSP, the initiating LSR has a priori knowledge about
number of egress nodes and their addresses. Hence it possible to
Missing "is" after "it".
continue processing till a valid response has been received from each
end-point, provided the responses can be matched correctly to the
egress nodes.
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