[SunHELP] How to Install 2nd NIC and assign IP to it

[Brian Hechinger]

> That sounds odd. 

not at all.

> A default gateway is where to send the packets if there are
> no specific routes defined. How could one have 2 default gateways?

say i have two links to the internet, a primary and a secondary.  the primary
is the prefered route and the secondary is a backup.  use the primary as long
as it exists, else use the backup.

heed the following warnings however:

a) this should only be done on machines that are designated as routers.  if
   you need to give each host dual gateways you should probably re-evaluate
   your network setup.

b) the other end needs to be aware of this as well.  for the most part if all
   connections are initiated from your network (you are only browsing from home
   let's say) then routing should just generally work since the remote end will
   probably route return packets back over the interface that they originated
   from.  this is not going to be 100% true, but in general it should Just 
   Work(tm), but on the other hand, if you have servers on your network that
   need to be contacted from the internet, you should probably have both ends
   of the links using dynamic routing so that they can figure things out on
   their own, at which point default routes become less important due to the
   routing protocols used.

c) if you are adding a second NIC to your machine in the hopes of making it
   a router/firewall/whatever between your network and the internet you do
   not want dual default routes since you should know enough about your internal
   network to be able to put much more narrow routes in your table (172.16.0.0
   goes to internal, etc)

that's all that pops into my head for the moment.  keep in mind i'm a solaris
admin not a network admin, so i am definitely not a network expert.  just a
guy who's been farting around with this stuff long enough to have a fairly
good understanding of how it all works.

cheers,

-brian