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Date:      Sat, 19 Jan 2008 03:10:38 +0530
From:      wahjava.ml@gmail.com (Ashish Shukla =?utf-8?B?4KSG4KS24KWA4KS3IA==?= =?utf-8?B?4KS24KWB4KSV4KWN4KSy?=)
To:        Ewald Jenisch <a@jenisch.at>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Anycast DNS - anybody?
Message-ID:  <87r6geke21.fsf@chateau.d.lf>
In-Reply-To: <20080118150214.GA3092@aurora.oekb.co.at> (Ewald Jenisch's message of "Fri\, 18 Jan 2008 16\:02\:14 +0100")
References:  <20080118150214.GA3092@aurora.oekb.co.at>

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>>>>> Regarding Anycast DNS - anybody?; Ewald Jenisch <a@jenisch.at> adds:
    Ewald> Hi,

    Ewald> Has anybody out there configured anycast DNS (where multiple ins=
tances
    Ewald> of a DNS-server run under the same IP-address in different parts=
 of
    Ewald> the network) under FreeBSD?

AFAIK, anycast requires magic at routing level. So that user will
connect to the nearest DNS server (holding the anycast address).

    Ewald> I'm looking for some hints to get started, but googling around d=
idn't
    Ewald> provide much info on that topic...

It has do with routing so you need to investigate on routing
protocols, like RIP, etc.

192.168.1.1     10.0.0.1        network         10.0.0.2     192.168.1.1
 [server1] --- [router1]  =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D    [router2] ---  [server2]

router1, router2 -- redundant routers connecting to different ISPs

So if router2 receives packet destined for 192.168.1.1, instead of sending =
to
server1 it'll send it to server2, since server2 is nearest to it, and
vice versa. Above is a very simple configuration describing anycast.

Since Anycast works only for connection-less protocols, you don't need
to keep TCP connections synchronized between two servers, although both ser=
vers
should behave identically, i.e. return similar records.

BtW, I've never implemented anycast ever, so its fully based on my imaginat=
ion.

HTH
=2D-=20
Ashish Shukla =E0=A4=86=E0=A4=B6=E0=A5=80=E0=A4=B7 =E0=A4=B6=E0=A5=81=E0=A4=
=95=E0=A5=8D=E0=A4=B2                      http://wahjava.wordpress.com/
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=B7- =C2=B7- =C2=B7--=C2=B7-=C2=B7 --=C2=B7 -- =C2=B7- =C2=B7=C2=B7 =C2=B7-=
=C2=B7=C2=B7 =C2=B7-=C2=B7-=C2=B7- -=C2=B7-=C2=B7 --- --

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