[Techtalk] Dual Homes instead of router?

[Conor Daly]

Potentially dumb question...

Is it reasonable to dual home a set of machines instead of buying a router?

More specifically, we have a routable class C IP block (192.xxx.xxx.xxx, NOT
in the 192.168.255.255 range) which is entirely behind a NAT gateway to the 
internet so none of these IPs are actually out there on the 'net.  We are 
currently down to less than 10 spare IP addys for new equipment.  The 
proposed solutions (from the consultants) are 

1. Cheap (EUR2600) router with 100Mbit uplink to our existing 100Mbit switch.
   everything on the 10.xxx.xxx.xxx side of the router will have to share that
   100Mbit link to everything on the 192.xxx.xxx.xxx side and to the
   internet.

2. Expensive (EUR35k) routing switch.
   Everything plugs into this switch and it handles the routing.  everything
   gets (potentially) 100Mbit to everything else.

We can't just renumber everything to 10.xxx.xxx.xxx since there are significant
numbers of applications with the 192.xxx.xxx.xxx numbers hardcoded including
stuff at the other end of leased lines into Europe.  I thought of dual
homing the servers and allowing these to handle any routing requirements.
Does this look like an extremely silly / unworkable / administrative
headache type solution or is it just not likely to make any money for the
consultants so they didn't mention it?

We have about 20-30 servers which would need to keep their 192.xxx.xxx.xxx
IPs and about 10-15 printers which might not be capable of being dual homed
in anycase (but these are generally operated on queues hosted by some of the
above servers so that wouldn't be a problem.  The servers are a mix of MS NT
and W2K, *NIX (IRIX, ULTRIX, SOLARIS, *BSD, LINUX, AIX) and a couple of
creaking VAXen on a Thick Ethernet backbone.  

AFAICT, a dual homed setup here would require each server to be set up with
a dual IP and twin DNS for each segment (thus allowing "joshua.met.ie" to
resolve to 192.xxx.xxx.34 for the 192.xxx.xxx.xxx hosts and "joshua.met.ie"
to resolve to 10.xxx.xxx.34 for the 10.xxx.xxx.xxx hosts)

Conor (Figuring the above would go quite well with a nice pasta sauce and a
       bottle of Chianti)
-- 
Conor Daly 
Met Eireann, Glasnevin Hill, Dublin 9, Ireland
Ph +353 1 8064276 Fax +353 1 8064247
------------------------------------
bofh.irmet.ie running RedHat Linux  3:10pm  up 24 days,  3:38,  4 users,  load average: 0.02, 0.16, 0.31


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