topic Re: Dual NIC configuration in UCX in Operating System - OpenVMS

Dual NIC configuration in UCX

Dirk Bogaerts — Thu, 01 Sep 2005 04:06:21 GMT

Hi,

AS1200 running OpenVMS V7.1-1H2 / UCX Version V4.2 - ECO 1 (yes, I know, old stuff, but upgrade is not an option) with 2 DE500 nic's.
The second nic was recently configured in UCX, same subnet, etc. as first one, only new hostname and new IP-address (in the same range as the first one). The purpose of the second nic is for the central backup-system (lan-based connections to vms-clients) to connect to the new nic, freeing the main nic from all that bu traffic.

Everything seems to work OK, only when I disconnect a network cable, outgoing traffic (ping) seems to stop. Incoming ping's only fail on the disconnected nic.

Is all outgoing IP traffic stopped or was it just my session working through the disconnected nic that got stuck ? Any hint on how to monitor in detail traffic on each of the nic's ? Any suggestions to improve my dual nic config (with this OS-version; I know recent VMS/TCPIP has a lot more to offer) ?

Thanks,
Dirk

Re: Dual NIC configuration in UCX

Uwe Zessin — Thu, 01 Sep 2005 04:18:29 GMT

Two different network cards must belong to two different subnets - else, the routing layer does not work (properly) - data can be sent through the 'wrong' interface.

Re: Dual NIC configuration in UCX

Antoniov. — Thu, 01 Sep 2005 04:32:52 GMT

As Uwe said,
there is no way to choic outgoing device in same netmask.

Antonio Vigliotti

Re: Dual NIC configuration in UCX

Ian Miller. — Thu, 01 Sep 2005 05:13:07 GMT

As you said current VMS versions have more facilities to do this. Parhaps you need to revisit the reasons about why you can not upgrade. Its often that people have not actually thought what is involved.

As has been said, the 2nd network card has to have a different IP network address.

Re: Dual NIC configuration in UCX

Wim Van den Wyngaert — Thu, 01 Sep 2005 14:02:06 GMT

Dirk,

All routing is done based upon ucx sho rout.

If the second card only communicates with a certain backup node, make sure that after ucx startup the route to the backup node goes via the 2nd card.

It becomes more difficult if routers are between them ...

Wim@home (no vms, so untested)

Re: Dual NIC configuration in UCX

Colin Butcher — Thu, 01 Sep 2005 23:23:45 GMT

For your purpose here you need to have each adapter in a different subnet. That's the only way to ensure that the traffic is separated. So, the "backup LAN" must use a different IP address range and subnet mask to your "public LAN". You will need to ensure that the static routes are correctly configured so that the default gateway is via the "public LAN".

VMS / TCPIP Services will handle multiple adapters in the same subnet, but there's no way to force specific outbound sessions over a specific adapter. VMS V7.3-2 and TCPIP V5.4 (and later) do all sorts of good failover things with multiple adapters (both outbound and inbound), but that's not what you're looking for. All you need is basic traffic separation - so it's back to a simple configuration with different IP addresses and different subnets for each adapter.

Traffic monitoring is probably best done at NIC level by looking at the NIC counters with SDA - or use an external LAN analyser. Later versions of TCPIP Services have facilities to look at the BG devices - I can't remember what was in UCX V4.2.

As has been mentioned - consider upgrading to current versions if you can.

Assuming that you also run DECnet then you might want to ensure that you don't have Phase IV addressing enabled on both adapters - if so then they will both run with the same MAC address. That's OK if they're totally separate LANs (or VLANs through the same switch). It's dfinitely not OK if they're both connected to the same LAN or VLAN. I assume that you won't need DECnet on the "backup LAN" - which will be fine.

Check for other protocols too and disable them on the relevant adapter too if appropriate (eg: clustering traffic, LAT etc.).

Cheers, Colin.

Re: Dual NIC configuration in UCX

Dirk Bogaerts — Fri, 02 Sep 2005 17:39:49 GMT

Thanks all for the quick responses.
Special thanks to Colin for the comprehensive reply.

For the moment have to keep the 2 nic's in the same subnet (more company rules&restrictions than available subnets..).
100% separation of traffic is not an absolute must, I'll try to use SET SERVICE /ADDRESS= to force all 'backup' IP traffic to the 2nd nic; hopefully most of the 'general' IP will stay on the main nic (is UCX smart enough to avoid the congested nic when another nic is available ?).
During daytime, having both nic's in the same subnet might well improve performance of the 'general' IP traffic. And my initial fears that disconnecting/failing 1 nic would block all IP traffic, seems unfounded (at least on a more recent VMS 7.2/TCPIP5.1 test system)

And as to why VMS upgrade is not an option...sad story... application software not supported on more recent VMS; the future releases of the application will mean being forced to throw the Alphaserver out of the window and the application into the Windows of master Bill

Re: Dual NIC configuration in UCX

Dirk Bogaerts — Tue, 13 Sep 2005 04:59:39 GMT

just for info : SET SERVICE /ADDRESS= seems to work fine