topic Re: Two default gateways in Operating System - HP-UX

Two default gateways

Thomas Stanley_1 — Fri, 18 Mar 2005 15:27:35 GMT

I am working on configuring a BigIP network load balancer to work with an HP N-class server running HPUX 11.

I have noted something unusual and was wondering if anyone could shed some light on it.

In SAM, I show the default gateway as the IP address of the F5 box, which is what I tried setting it to. Yet if I run /sbin/set_parms addl_netwrk, it shows the default gateway as the original gateway. In the /etc/rc.config.d/netconf file, the gateway for the interface lan0 is the original gateway.
Also, both gateways show when doing a 'netstat -r'

When I implement the F5 the lan0 interface will be disabled via SAM and the eight additional nics that I have in the system will be running (each with its own IP in its own subnet)

Re: Two default gateways

RAC_1 — Fri, 18 Mar 2005 15:31:04 GMT

set it through SAm or set_params and do
through console do
/sbin/init.d/net stop;/sbin/init.d/net start

Re: Two default gateways

Thomas Stanley_1 — Fri, 18 Mar 2005 15:51:52 GMT

Would it also be possible to make changes in the netconf file, by setting the default gateway for each interface?

Re: Two default gateways

RAC_1 — Fri, 18 Mar 2005 15:58:28 GMT

I do not think it is possible. If you want to reach particular network through particular router/swtich, you can do that.

route add net "network" netmask "xx" "router" 1

Anil

Re: Two default gateways

Wilfred Chau_1 — Fri, 18 Mar 2005 18:23:31 GMT

Add it to /etc/rc.config.d/netconfig. Change
the [x] index as necessary.

ROUTE_DESTINATION[0]=default
ROUTE_MASK[0]=""
ROUTE_GATEWAY[0]="192.168.0.1"
ROUTE_COUNT[0]="1"
ROUTE_ARGS[0]=""

Per RAC example,
You can do
ROUTE_DESTINATION[1]="net 192.168.0.0"
ROUTE_MASK[1]=""
ROUTE_GATEWAY[1]="192.168.0.1"
ROUTE_COUNT[1]="1"
ROUTE_ARGS[1]=""

run, /sbin/init.d/net start
check with netstat -rn

Re: Two default gateways

Andrew Cowan — Sat, 19 Mar 2005 13:32:53 GMT

Wilfred is correct in that you can now have in effect two or more default gateways as HP-UX binds the route to the NIC adapter. This behaviour was first introduced in AIX, but now also exists in Linux.