topic Re: TCPIP Default routes in Operating System - OpenVMS

TCPIP Default routes

Mike Hedderly — Tue, 16 May 2006 05:07:47 GMT

I'm running Openvms7.3-2 and TCPIP services 5.4 eco 4.

I have two interfaces defined in different subnets. Each Interface is connected to a switch and each switch connected to a router.

I have tried to define a default route for each subnet. But it only seems to use the first route defined. Last week one of the routers died and we where unable to telnet on to the system. Once I logged on a manaully removed the dead default route, all was ok. Is there anyway to configure these routes to do this dynamically.

Re: TCPIP Default routes

Willem Grooters — Tue, 16 May 2006 06:10:50 GMT

Since "Default" should be read "to be used whenever anything else fails", I think it's normal the system will use just the first entry it will find. That means that the first "default" route will be used, no matter on what interface.
If that router (= gateway) fails, that route must be disabled (TCPIP IP SET NOROUTE...) before the other default route will be used. Defining routes to 0.0.0.0 explicitly per subnet (by $ TCPIP SET ROUTE/DESTINATION=0.0.0.0/NETWORK/GATEWAY= will suffer the same problem, I think.

You may be able to solve this by defining ONE default route and specify the gateway by name, and define the translation inside (external) DNS; failure of one server would require a change in DNS. It may, however, need some kind of reset of the address translation chaches in VMS.

Re: TCPIP Default routes

Wim Van den Wyngaert — Tue, 16 May 2006 06:46:18 GMT

You can setup multiple (permanent) default routes. At startup time, TCP will use the route that responds (the first one only ?). Routes that are unreachable will be rejected.

TCP will not monitor the state of the interface. There are versions of TCP that do a round robin when doing retransmissions but I guess the VMS version isn't doing that.

Wim