Re: [mpls] MPLS-RT review of draft-bonica-mpls-self-ping

["[e-mail]" <[e-mail]>]

Hi authors,
I finish the MPLS-RT review for draft-bonica-mpls-self-04, and the document is clearly written.
The self-ping is useful in a normal network scenarios, and also will not work if uRPF is enabled on the egress. But there are more scenarios where self-ping will fail as below:
1. If one transite node wrongly installs a output lable as implicit null, then the self-ping reply message will be sent back by the next node. Then the ingress node will verify that the RSVP-TE LSP is OK, but the fact is the LSP is broken. That is self-ping could not detect the LSP down because of wrong label installation. 
2. In the network with link aggregation or other load balance mechanism, the self-ping may also provide wrong LSP validation information, but LSP Ping could support that scenario.
3. Reply message may not be able to route back to the ingress if the ingress IP address is not directly IP reachable for the egress node.
It is better to describe all fail scenarios in an independent section, like section 4. It should be highlighted to the reader.

For section 6, originally ingress could identify the LSP ping packet with well-known UDP port, and configure ACL rule to reduce risk of attack. But now it is more difficult to filter the packet with access list, which may increase the risk.

Overall, I have some concern with the tool of self-ping, especally to this fail scenarios. Let's assume ingress node receives the RESV message from downstream, then do self-ping, then:
1. if success, you are not ensured that the LSP is really OK.
2. if fail, you still have to use LSP Ping again.



Regards
Lizhong
 
From: Loa Andersson
Date: 2015-02-24 17:42
To: Carlos Pignataro (cpignata); Gregory Mirsky; Mach Chen; Lizhong Jin; [e-mail]; [e-mail]; <[e-mail]>
Subject: MPLS-RT review of draft-bonica-mpls-self-ping
Carlos, Greg, Mach and Lizhong,
 
You have be selected as MPLS-RT reviewers for draft-bonica-mpls-self-
ping-04.
 
Note to authors: You have been CC'd on this email so that you can know
that this review is going on. However, please do not review your own
document.
 
Reviews should comment on whether the document is coherent, is it
useful (ie, is it likely to be actually useful in operational
networks), and is the document technically sound?  We are interested
in knowing whether the document is ready to be considered for WG
adoption (ie, it doesn't have to be perfect at this point, but should be
a good start).
 
Reviews should be sent to the document authors, WG co-chairs and
WG secretary, and CC'd to the MPLS WG email list. If necessary, comments
may be sent privately to only the WG chairs.
 
If you have technical comments you should try to be explicit about what
*really* need to be resolved before adopting it as a working group
document, and what can wait until the document is a working group
document and the working group has the revision control.
 
Are you able to review this draft by Mar 11, 2015? Please respond in a
timely fashion.
 
 
Thanks, Loa
(as MPLS WG chair)
-- 
 
 
Loa Andersson                        email: [e-mail]
Senior MPLS Expert                          [e-mail]
Huawei Technologies (consultant)     phone: [phone]