nanog mailing list archives
Re: nested prefixes in Internet
From: Michael Hallgren <mh () xalto net>
Date: Tue, 27 Sep 2016 19:52:54 +0200
Hi Martin, What do you want to do? Move from A to B or add A to B? Cheers, mh Le 27 sept. 2016 17:52, à 17:52, Mel Beckman <mel () beckman org> a écrit:
Precisely. This is how it's done by providers I've worked with. -mel beckmanOn Sep 27, 2016, at 7:06 AM, Roy <r.engehausen () gmail com> wrote: Option 3? ISP A announces the /19 and the /24 while ISP B does just the /24On 9/27/2016 4:20 AM, Martin T wrote: Hi, let's assume that there is an ISP "A" operating in Europe region who has /19 IPv4 allocation from RIPE. From this /19 they have leased/24to ISP "B" who is multi-homed. This means that ISP "B" would like to announce this /24 prefix to ISP "A" and also to ISP "C". AFAIK this gives two possibilities: 1) Deaggregate /19 in ISP "A" network and create "inetnum" and"route"objects for all those networks to RIPE database. This means that ISP "A" announces around dozen IPv4 prefixes to Internet except this /24 and ISP "B" announces this specific /24 to Internet. 2) ISP "A" continues to announce this /19 to Internet and at thesametime ISP "B" starts to announce /24 to Internet. As this /24 is more-specific than /19, then traffic to hosts in this /24 will endupin ISP "B" network. Which approach is better? To me the second one seems to be better because it keeps the IPv4 routing-table smaller and requires ISP "A" to make no deaggregation related configuration changes. Only bitweirdbehavior I can see with the second option is that if ISP "B" stopsforsome reason announcing this /24 network to Internet, then traffic to hosts in this /24 gets to ISP "A" network and is blackholed there. thanks, Martin
Current thread:
- nested prefixes in Internet Martin T (Sep 27)
- Re: nested prefixes in Internet Florian Weimer (Sep 27)
- Re: nested prefixes in Internet Roy (Sep 27)
- Re: nested prefixes in Internet Mel Beckman (Sep 27)
- Re: nested prefixes in Internet Michael Hallgren (Sep 27)
- Re: nested prefixes in Internet Mel Beckman (Sep 27)