Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!samsung!umich!sharkey!bnlux0!drs
From: drs@bnlux0.bnl.gov (David R. Stampf)
Newsgroups: comp.dcom.sys.cisco
Subject: Configuration problem
Message-ID: <2392@bnlux0.bnl.gov>
Date: 4 Jan 91 19:13:43 GMT
Organization: Brookhaven National Lab
Lines: 39


	Cisco routers always seem to be reliable and fast, but always seem to
fall short of letting you do what you *want* to do. Here is the latest problem
we face.

	I'd like to assign a second IP address to an ethernet interface on my
router. The reason is that I'm about 40 numbers over what would pass for a
subnet range, i.e. 550 hosts vs 511 slots. This is a short term problem which
will be fixed when we get the nerve to cut our ethernet cable. Cisco provides
the "ip address ip-address subnet-mask secondary" command which allows me to
assign two addresses to an interface, one on each of two subnets. This works
like a charm *except* that the router will not send any routing info (RIP) to the
secondary network. This is apparently by design since there is a warning in my
manual that says "Secondary address are treated like primary addresses except
that the system never generates datagrams with secondary source addresses". I
think that means it does not send routing packets.

	Well, I can hard wire routes on all of my hosts on the secondary network,
but that would be a problem since most of the new systems are user maintained, and
it is hard enough to explain subnets to the uninitiated. Besides, sending routing
info seems like a natural job for a router. Even if I could convince the cisco to
just send out default to the secondary net I would be a lot happier. 

	Of course, another possibility is to use a spare ethernet port on the router
to connect to the same physical ethernet but have a different subnet address. I
feel less comfortable about that idea tho - it also involves more hardware, and I
suspect there would be many more collisions on the ethernet.

	The funny part is that I would also like to have the router send out *fewer*
routing packets on the primary subnet. Every 30 seconds, we get a blast of
approximately 200 networks advertised by rip from our external connections when
all we really want to see on our network is "default". 

	Feast or famine.

	Any suggestions?


	Dave Stampf