Adding Additional Cluster LAN Connections

[Rick Dyson]

I am researching what is required to add additional ethernet LAN connections to my AlphaServers to complement the FDDI connections currently used. At this time I only want the 10BaseT connections to carry SCS traffic, if needed.

What docs address this? I see lots of overview ones that mention how you should do it, but I can't find one that says HOW to do it and if it requires specific configuration or downtime, etc.

I don't want to have to define new DECnet and/or TCP/IP configs and addresses to the circuits and I don't think I am looking for IP Failover, etc.

Just a backdoor path for the health of the Cluster in the event of a FDDI disconnect.

Thanks,
Rick

[Ian Miller. · Accepted solution]

having added the extra lan interface cards you can control the relative priority using SCACP. By default VMS will favor the faster interfaces but you can set a priority.
See
http://h71000.www7.hp.com/doc/732FINAL/6048/6048pro_004.html#scacp_ch
and in particular
http://h71000.www7.hp.com/doc/732FINAL/6048/6048pro_004.html#scacp_ch

[Rick Dyson]

Ah. I've been digging around in Cluster Config and LANCP manuals. I did not look at the SCA ones (duh!).

I knew from years of hearing it said that VMS would automagically use the best (i.e., FDDI) method.

I'm mostly interested in the question: Can I just plug in an ethernet cable and it will find the route without my help? (Maybe only on reboot?)

I will dig around in those manuals. I am sure the answer will be in there.

Rick

[Uwe Zessin]

When a system boots, the cluster software will automatically go to all supported LAN adapters and start sending hello messages. You can turn it off later on, but you don't need to configure beforehand.

[Rick Dyson]

Great! I had not yet found that in the SCA chapter.

What about just plugging into the empty EWA ports on a live system currently in an FDDI cluster?

Will it find it on it's own, or if I kick it with an SCACP command? Any possibility of a problem connecting while up and running!

rick

[Volker Halle]

Rick,

no problem at all. SCS protocol is already running on all your LAN adapters, it just can't send or receive anything, if you haven't plugged in the network cable.

You can easily check with:

ANAL/SYS
SDA> SHOW LAN

and you'll see the SCA protocol enabled on all your network adapters.

Volker.

[Keith Parris]

Note that if you have raised NISCS_MAX_PKTSZ above the default value of 1498 bytes, then FDDI, which can use larger packet sizes, will always be preferred over Fast Ethernet or 10-megabit Ethernet, which are limited to 1498-byte payloads.

As you work with and change your LAN configuration, you might find a couple of Freeware tools from [KP_CLUSTERTOOLS] on the V6 Freeware CD to be helpful. SHOW_SEGMENTS.COM will draw a picture of the LAN segments which are carrying SCS traffic. SHOW_PATHS_ECS will tell you which paths are currently in the Equivalent Channel Set and thus used by PEDRIVER for transmitting SCS packets.

[Rick Dyson]

Thank you all very much. This helped me a lot. Cheating and getting the answer
before the research helps me follow the manuals easier. :)

I should be able to avert any future FDDI hiccups (like I had recently that genereated a CLUEXIT on 3 of 4 nodes) because the nodes would have been able to ride out the glitch by switching to ethernet for a period.

It all looks easier than I had assumed. As long as I don't want to also run DECNet or TCP/IP on the ethernet circuits.

Rick