Re: [Lsvr] Tsvart early review of draft-ietf-lsvr-l3dl-03
Randy Bush <randy@psg.com> Tue, 05 May 2020 22:45 UTC
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Date: Tue, 05 May 2020 15:45:09 -0700
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From: Randy Bush <randy@psg.com>
To: Joerg Ott via Datatracker <noreply@ietf.org>
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Subject: Re: [Lsvr] Tsvart early review of draft-ietf-lsvr-l3dl-03
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wow! thanks! great review. unfortunately the wg has gone dormant, so we have let the l3dl drafts expire. should it ever wake up, i will happly merge in your excellent suggestions. again, thank you! randy > Reviewer: Joerg Ott > Review result: Ready with Issues > > The draft describes a peer/neighbour discovery mechanisms for large-scale L2/L3 > topologies in data centres. The aim is provide a protocol by means of which the > involved nodes can learn about other nodes connected to their (broadcast or > point-to-point) L2 links and about their respectively support encapsulation > schemes, identifiers, L2/L3 addresses, etc. This information is then provided > to a higher layer for further processing. > > The document is well written and fairly easy to follow, but could benefit from > a bit of extra context and target application domain in the introduction. E.g., > explaining explicitly who would talk L3DL to whom. > > >From a transport perspective, I see three potential issues that deserve > clarification or reconsideration: > > 1. Section 10 spells out a default HELLO interval of 60 seconds. With a large > broadcast domain, this may create quite a bit of traffic. While this may not be > an issue in well-provisioned data center networks, a remark about sensible > value ranges and the implications may be worthwhile. Just to provide some > guidelines to implementers (who want to offer choices) and operators (who pick > them). > > 2. Section 10 also suggest that in response to HELLO messages nodes will issue > OPEN PDUs to newly discovered peers. This appears to bear the clear risk of an > OPEN implosion when many system come up at the same time. Shouldn't guidance be > given to avoid repeated traffic surges and possible losses and thus unnecessary > delays? (I noted that other places foresee exponential backoff when > retransmitting OPEN and other ACKed PDUs). > > 3. When the protocol applies fragmentation, should there be a note on > preventing bursts? > > Other notes: > Section 7 on the checksum needs more detail. It also talks about a "suggested" > algorithm but this should be clearly mandated or way to choose one by means of > configuration for a complete data centre would need to be made explicit. I also > assume that the pseudo code on p.11 would benefit from a leader '0' in > 0xffffffff -> 0x0ffffffff, otherwise expansion to 64 bits might fill the high > order bits with '1's, which is clearly not intended. > > Section 11, p.17, second to last para ("If a properly authenticated..."). From > the text, it is unclear what is meant by an "OPEN with the Serial Number of the > last data received". > > I am curious about the error code, providing 16 bits for additional > explanation. Why not a text field? Also wondering if repeated retries (due to > failure, not lost packets) could yield fast repeated transmissions. > > Section 15, should the KEEPALIVE interval have suggested (lower) bounds? > At the top of p.26, it says "One per second is the default", the previous page > at the bottom refers to the inter-KEEPALIVE interval of ten seconds. Not sure > if the two are the same, I suppose so. If they are, the numbers should match. > If they are not, we'll need some extra text to explain the difference. > > Nits: > There are two spellings of "Encapsulation", capitalised and lower case. Use one > consistently. p10, first para: comprise -> comprising > > >
- [Lsvr] Tsvart early review of draft-ietf-lsvr-l3d… Joerg Ott via Datatracker
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Randy Bush
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Joerg Ott
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Van De Velde, Gunter (Nokia - BE/Antwerp)
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Randy Bush
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Randy Bush
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Randy Bush
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Rob Austein
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Joerg Ott
- Re: [Lsvr] Tsvart early review of draft-ietf-lsvr… Randy Bush
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Joerg Ott
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Randy Bush
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Joerg Ott
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Randy Bush
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Joerg Ott
- Re: [Lsvr] [Tsv-art] Tsvart early review of draft… Randy Bush