nanog mailing list archives
Re: Partial vs Full tables
From: Saku Ytti <saku () ytti fi>
Date: Tue, 9 Jun 2020 09:29:33 +0300
On Tue, 9 Jun 2020 at 02:22, Josh Hoppes <josh.hoppes () gmail com> wrote:
Juniper Networks has also tried using Bloom filters. https://patents.google.com/patent/US20170187624 I think the QFX10002 was the first product they made which used this approach. https://forums.juniper.net/t5/Archive/Juniper-QFX10002-Technical-Overview/ba-p/270358
How they use it is not clear and it's not communicated in the article. Bloom filter of course only answers to you 'maybe' or 'no', which is not sufficient for egress rewrite information. The article also implies the bloom filter is in HMC, which I don't believe. I suspect roughly what is happening a) there are N bloom filters on-chip b) lookup is ran parallel to all N bloom filters c) bloom filters which give 'maybe' answer, cause lookup to off-chip HMC The naive approach would be 1 bloom filter per-netmask, so you have LEM only lookups in HMC, and on-chip tells which LEM lookups to do, to reduce LEM count from 32 to something rather less. But this surely isn't what they are doing, because the hash population is very different for /1 than it is to /24 and you want a reasonably fair balance, while guaranteeing LEM to off-chip. But I'm sure this is the gist of it, imprecise fast on-chip allowing LEM only off-chip. -- ++ytti
Current thread:
- Re: Partial vs Full tables, (continued)
- Re: Partial vs Full tables Saku Ytti (Jun 07)
- Re: Partial vs Full tables Baldur Norddahl (Jun 08)
- Re: Partial vs Full tables William Herrin (Jun 08)
- Re: Partial vs Full tables Nick Hilliard (Jun 08)
- Re: Partial vs Full tables Joe Greco (Jun 08)
- Re: Partial vs Full tables William Herrin (Jun 08)
- Re: Partial vs Full tables Mike Hammett (Jun 08)
- Message not available
- Re: Partial vs Full tables William Herrin (Jun 08)
- Re: Partial vs Full tables Josh Hoppes (Jun 08)
- Re: Partial vs Full tables Anoop Ghanwani (Jun 08)
- Re: Partial vs Full tables Saku Ytti (Jun 08)
- Re: Partial vs Full tables Mike Hammett (Jun 06)
- Re: Partial vs Full tables Mark Tinka (Jun 09)
- Re: Partial vs Full tables Tom Beecher (Jun 05)
- Re: Partial vs Full tables Baldur Norddahl (Jun 05)
- Re: Partial vs Full tables Ryan Rawdon (Jun 06)