Distributing DNS servers

[Barry Margolin]

In article <Pine.BSF.4.01.9908290132360.1537-100000 at phoenix.aye.net>,
Barrett Richardson  <barrett at phoenix.aye.net> wrote:
>Draft draft-ietf-catalone-hadns-00.txt may be worth a gander.
>It (and others) are available for perusal at
>
>http://info.internet.isi.edu/1/in-drafts

According to my copy of the I-D index, the name of this document is
draft-catalone-rockell-hadns-00.txt.

The technique we use is similar in spirit to that in the above document,
but not identical.  We use OSPF rather than BGP to distribute the common IP
address routes.  They're all within our CIDR block that we announce to all
our BGP peers.

Also, we don't actually run a routing process on the servers themselves.
Instead, we configure static routes on the upstream router.  So, if we have
a server whose real address is 192.168.10.33 implementing the common
address 4.2.2.1, the upstream router is configured with:

ip route 4.2.2.1 192.168.10.33

We then redistribute this static route into OSPF.  We considered running
gated on the servers, but decided that we had more experience with router
configurations and were more comfortable with this approach.  It's true
that running a routing process on the server would cause routes to be
dropped automatically if the server crashes.  But we felt it was more
likely that named would die or hang than that a Sun workstation would
crash; since we have to implement monitoring for that and procedures to
remove the static route manually in such cases, it wouldn't be worth the
extra complexity of running a routing protocol on the server just to handle
one specific case.  Some day we might change this; for instance, if the
named monitoring could automatically reconfigure gated to stop advertising
the route, it would be reasonable to run gated.

-- 
Barry Margolin, barmar at bbnplanet.com
GTE Internetworking, Powered by BBN, Burlington, MA
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