Elvis Buffong wrote:

> I have a networking question. I have a default gateway setup on a 3000
> running 5.5pp4. For some unknown reason this gateway seems to take on an
> additional gateway( IP address) that is assigned to a router. HP has looked
> at it before and said that they don't have a fix for this problem. In
> essence, the router is sending to the HP an additional gateway which has not
> been assigned within the 3000. HP said that I should use Nettool to delete
> it but, it always returns even when I do a NETCONTROL UPDATE option. Does
> anyone have any ideas?

This is likely due to an ICMP Redirect being sent back from your
"default" gateway.  Essentially, the router receives a packet from
your 3000 on whatever interface your system resides on.  It then
examines the destination IP address and looks up the "next hop"
designation from it's routing table.  If the "next hop" resides on
the same segment as your 3000, or more generally, if a packet is
received on an interface and the next hop resides on the SAME
interface, the router sends an ICMP Redirect to the source machine
with the IP address of the next hop.  Put another way, the redirect
is saying "Don't bother me with this, you're wasting my time - you
should send directly to <next-hop> which is where I'll have to send
it anyway".

Without more details I can't tell you exactly "why" you are getting
the redirects, but that is the only way I know of that the 3000 can
"learn" a new gateway all by itself.  If you have multiple routers
on your segment, or un*x/linux machines with multiple interfaces and
running the 'routed' daemon, or a number of other factors can cause
the redirects.  Something makes the router think it is not the least
cost/shortest path to your destination.

It is possible to disable redirects on some routers, but you'll have
to sell your case to your network staff as the router is sending the
redirects for a good reason, and it knows much better than your 3000
why.  Is this causing you a legitimate problem (traffic not getting
through) or are you just curious where the gateway came from?

Redirects are a Good Thing(tm).  It keeps you from having to keep
routing tables yourself.

Jeff Kell <[log in to unmask]>