Re: [pim] pim-dr-improvement wglc

"Holland, Jake" <> Mon, 14 January 2019 22:08 UTC

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From: "Holland, Jake" <>
To: Michael McBride <>, "" <>
Thread-Topic: [pim] pim-dr-improvement wglc
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Date: Mon, 14 Jan 2019 22:07:46 +0000
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Subject: Re: [pim] pim-dr-improvement wglc
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I think the extension is a good idea and that this doc gives a good
explanation of how it works. However, I think there’s some issues that
should be addressed before publication as a Standards Track RFC.

Major issues:
1. The security considerations section seems too thin. (The complete
contents of the section are “For general PIM Security Considerations.”)

1.a. I think there are some security implications because of
the new stickiness in the DR election process. For instance, in when describing what
happens when a DR has been impersonated, it implies there’s a
mitigation (“[The impersonated] node typically will be able to detect
the anomaly and, possibly, restart a new election.”)

But because the DR is more sticky with this new extension, I think the
kind of temporary disruption would have a more permanent effect that
the impersonated node could not mitigate. I might be wrong about that
being actually more dangerous, but it worries me that there’s no
mention of issues like these in the security considerations section.

I think for this point, it might be enough to just say that the
election process may be more vulnerable to temporary disruption because
the DR election is more persistent, and that this increases the
importance of using source authentication to avoid DoS from malicious

1.b. I think this probably should mention that BFD security
considerations are applicable also, or the considerations for whatever
DR failure detection mechanism is used.

2. There should probably be a reference to BFD, and perhaps other
fast failure detection mechanisms, if they’re recommended.

More generally, it seems to me that the speed of DR failure detection
is of critical importance in using this mechanism, so the one brief
mention (which doesn't explain the pros and cons of faster detection or
make any recommendations about technologies to use) seems like it
skims past a key point without explaining it in depth.

Minor/editorial issues:

1. In section 3.2, it probably should talk about the IP version in the
PIM message, instead of IP version supported by the network. The way
it’s written, it seems to make it impossible to run a dual-stacked
network with 2 instances of PIM, but I don’t think that’s the intent.

2. Should the reference to 2328 be informative instead of normative? It
seems like it’s only used as an example.

3. The IANA considerations section should follow the guidelines from
RFC 8126 section 1.3 (exact name of the registry, for instance). It
also seems useful to make 2 separate values, TBD1 and TBD2 instead of
using TBD for both.

4. “SW” is not defined in the diagram in Figure 1. I think the 2 SW
boxes are Layer 2 switches on the same LAN, but I’m not certain.

5. In section 4, I think "MUST not" in the last paragraph should have
NOT capitalized?

6. I don't understand the meaning of "The treatment" as the title
for section 4.5.

7. There are a lot of English language nits. I saw that Greg covered
several of them, so I’ll just mention the ones I saw in sections he
didn’t cover:

section 1:
“can be adjust to” -> “can be adjusted to”
“Still, may multicast packets” – should this be “many” instead of “may”?
“new comers” is one word (this appears several times in the doc)
I’m not certain, but I think each time the word “Ethernet” is used, “LAN” was intended?
“new comers which has a higher”: has->have

... (skipping sections Greg Mirsky covered) ...

section 4.5:
“are start to work on the same time”
“when a new router start to work” -> starts to work
“fails or manually adjustment” -> fails or is manually adjusted

I had to stop early before finishing a catalogue of all the rest of the
issues I could find, but because of the very high density of nits, I’ll
suggest it might be a good idea to try using an English-language
proofreading service that works with technical documents.

This is not an endorsement, and I’ve never used their services, but as
an example of the kind of service I mean, here’s one I found in a few
moments with a search engine:

Thanks for this work, it seems like a useful extension.


From: Michael McBride <>;
Date: 2019-01-08 at 10:29
To: ""; <>;
Subject: [pim] pim-dr-improvement wglc

Happy New Year!

Today begins a two week wglc for draft-ietf-pim-dr-improvement-06. In Bangkok, 4 people indicated that they had read the draft and each agreed it’s ready for wglc. Let’s please read the draft one more time and confirm, on this list, that it’s ready to be sent to iesg.<>