Computers with multiple network interfaces.

If you use Isis2 on a computer that interfaces to multiple network devices, you should read this page, which offers suggestions about how to tell Isis2 how to configure itself.

Many machines have multiple network interfaces (use "ipconfig -a" to list them). Not all network interfaces are enabled for UDP and IP Multicast; for those that are, ipconfig will print an indication showing this to be the case. In its default mode, Isis picks the last of the IP4 network interfaces that supports IP multicast, but you can override this behavior in various ways. The easiest is to set values for ISIS NETMASK and ISIS SUBNET that will select for the desired network interface card. For example, on one machine recently we found that we needed to set ISIS NETMASK to (selecting the 24 high-order bits) and ISIS SUBNET to (requiring a match with Until we did this, UDP traffic was sent, but not received because Isis was binding, by default, to an interface that differed from the default interface for sending UDP traffic. We arrived at these two values by inspecting the available network interface IP addresses and the one we picked matched the IP address for the network interface that was apparently intended for public UDP and IP multicast traffic.

A second and perhaps better way to deal with interfaces is to just tell Isis which ones to use. You do this by listing the interfaces in ISIS NETWORKINTERFACES. For example, if ifconfig shows an Infiband NIC called ib0 and you want Isis2 to use that network interface, just set ISIS NETWORKINTERFACES=ib0. You can put a list of interface names, separated by commas.

EMULAB and other large clusters:

Keep in mind that there are some systems, such as EMULAB, on which some networks are reserved for specific purposes. Be careful not to configure Isis in ways that could allow it to select those interfaces, or you'll be in hot water with the local authorities! And keep in mind that when running Isis2 from a batch launch system, you will very often need to run Isis using its master/worker startup approach if your group is at all large. Isis can handle 100 nodes launching all at once, but 1000 can cause startup issues. That same 1000-member startup will be a breeze in the master/worker mode.

When using Isis2 on Linux platforms, please read the "Issue Tracker" posting on performance issues and adjust the kernel limits on socket send and receive buffer sizes as indicated. On Windows this issue does not arise.

Last edited Nov 19, 2015 at 7:57 PM by birman, version 1