Single Server with 4 GB ethernet ports

[Marc A Smith]

I know this is a very basic question, but this is the first time I've configured a server with multiple NICs that was not part of a cluster. We have a new rx6600 which will be running OVMS 8.3-1h1 and TCPip services for OVMS. There are 4 GB ethernet ports and I would like to spread the overhead across the 4 ports. This does not need to be true load balancing, a standard round robbin would work fine. I just need to know if I can assign each port a unique IP addr/host name and have our external DNS rotate the connection to the next interface? Thank in advance, Marc A Smith

[John Gillings]

Marc,

Take your pick! There are many ways to configure multiple adapters, each has their own set of characteristics. Check the documentation for:

LAN Failover (covers all protocols, but only one adapter active at a time)

Failsafe TCPIP (same IP address on all adapters, aggregate bandwidth)

Loadbroker (multiple IP addresses with DNS load balancing)

[Robert Gezelter · Accepted solution]

Marc,

With IP, in general, each adapter must have its own address (except in the presence of a feature like "Failsafe-IP").

Actually, for safety's (and maintenance's sake), you may want to consider how to deal with adapter/cable outages. It is important to consider that DNS round-robin applies for each translation supplied by the nameserver. This is on the average ok, but DNS translations are cached at various points in the network.

Failsafe-IP and similar schemes use ARP/RARP to point the underlying IEEE 802.3 transport to the other adapter.

- Bob Gezelter, http://www.rlgsc.com

[Robert Gezelter]

Marc,

I see that this is your first question in the ITRC OpenVMS Forum.

A somewhat belated "Welcome!". Also my, congratulations on your courtesy in quickly awarding points.

- Bob Gezelter, http://www.rlgsc.com

[Matt Muggeridge]

Always, with network traffic you need to consider inbound and outbound directions separately.

First consider the outbound direction:

At the most fundamental level, it is very easy to configure what you want. Simply configure all interfaces with addresses in the same subnet.

For outbound TCP connections, they will automatically be load-balanced across each interface. You get similar sharing of outbound traffic across interfaces with UDP, though it's not so deterministic.

Now the inbound direction:

For inbound traffic, setup a single DNS-alias which lists each of the four IP-addresses, (there is no requirement for them to be in the same subnet - that all depends on your network-topology). Each time a DNS query is required to resolve the DNS-alias, it will return the list of IP addresses in a round-robin fashion. Easiest to see this live using "nslookup".

Then if you care about high-availability, go ahead and look into the various solutions pointed out by John G.

All the best,
Matt.

[Colin Butcher]

Having built several such systems recently, do consider using "failsafe IP" to protect yourself from failures. You might also want to think about using "LAN failover" (equivalent to NIC teaming) as well. It might also be useful to look at tagged VLANs. (failsafe IP on VLAN virtual adapters over LAN failover NICs anyone?).

The fact that it's not clustered isn't really relevant to the IP interface configuration.

Think about the failure scenarios and how you'll continue to have traffic flowing, preferably without users having to reconnect or restart their sessions.

I know it's quite general, but you might find this of use: http://www.downloads.xdelta.co.uk/2008/2008_11_19-networking-colin_butcher-v1_0.pdf - it's basically the slides from one of the OpenVMS technical update sessions, without the audio, arm waving and diagram drawing.

Do look in the OpenVMS technical journals too - some of them have good network related articles, such as Matt's description of "failsafe IP".

Cheers, Colin (http://www.xdelta.co.uk).

[Marc A Smith]

Thank you all for the help and direction. I'm relatively new at this and appreciate the advice. All of the responses have been very useful and I think I've got it covered now.

[Marc A Smith]

Once again, thanks to all for the info. I think I'll explore all of the suggestions on my test server and see which works best in our environment.