[192025] in North American Network Operators' Group
Re: nested prefixes in Internet
daemon@ATHENA.MIT.EDU (joel jaeggli)
Mon Oct 10 12:17:03 2016
X-Original-To: nanog@nanog.org
To: Roy <r.engehausen@gmail.com>
From: joel jaeggli <joelja@bogus.com>
Date: Mon, 10 Oct 2016 09:16:56 -0700
In-Reply-To: <67d56263-18da-18ff-3f1e-2e827ba981db@gmail.com>
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From: joel jaeggli <joelja@bogus.com>
To: Roy <r.engehausen@gmail.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Message-ID: <ccb52050-8f89-514e-1104-f5f3cfcea1f9@bogus.com>
Subject: Re: nested prefixes in Internet
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<8737ka4j1q.fsf@mid.deneb.enyo.de>
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On 10/10/16 9:04 AM, Roy wrote:
>
>
> The solution proposed allows ISP-B to use both paths at the same time,
> needs ISP-C to minimal changes, and has low impact on the global
> routing tables.. I have successfully used it in the past and my old
> company is still using it today.
Having two parties in control of a prefix announcement is a bit of a
disaster. ISP A becomes partitioned from isp B isp B does not withdraw
the covering aggregate and black-holes the of ISP A that lands on it's=20
edge. bummer.
>
> .On 10/9/2016 11:50 PM, Martin T wrote:
>> Florian:
>>
>> as I told in my initial e-mail, ISP-B is multi-homed, i.e connected to=
>> ISP-A(who leases the /24 to ISP-B from their /19 block) and also to
>> ISP-C. ISP-B wants to announce this /24 both to ISP-A and ISP-C.
>> That's the reason why either solution 1 or 2 in my initial e-mail is
>> needed.
>>
>> However, I would like to hear from Roy and Mel why do they prefer a
>> third option where ISP A announces the /19 and the /24 while ISP B
>> does just the /24.
>>
>>
>> thanks,
>> Martin
>>
>> On Wed, Oct 5, 2016 at 11:50 PM, Florian Weimer <fw@deneb.enyo.de>
>> wrote:
>>> * Martin T.:
>>>
>>>> Florian:
>>>>
>>>>> Are the autonomous systems for the /19 and /24 connected directly?
>>>> Yes they are.
>>> Then deaggregation really isn't necessary at all.
>>>
>>>>> (1) can be better from B's perspective because it prevents certain
>>>>> routing table optimizations (due to the lack of the covering prefix=
)
>>>> What kind of routing table optimizations are possible if covering /1=
9
>>>> prefix is also present in global routing table?
>>> The /24 prefix could arguably be dropped and ignored for routing
>>> decisions.
>
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