Using dlpiping to test VCS heartbeats

Imagine you have a couple of hosts with Veritas Cluster Server (VCS) installed, configured with the recommended two heartbeat interfaces. Only, you’re not sure whether they’re able to communicate or not!

In the normal TCP/IP world, you’d just ping the hosts via the relevant network interfaces. However, VCS heartbeats run over the Low Latency Transport (LLT) protocol, which operates at layer 2 of the OSI model. Therefore, its interfaces don’t require IP addresses to be configured on them. Enter dlpiping! A utility that allows us to test connectivity using the LLT protocol!

The VRTSllt package installs the dlipiping command in /opt/VRTSllt, so it requires that you’ve gone through the VCS installation process.

First, decide the host that you want to test connectivity to. Identify one of your heartbeat interfaces. In my case, we’re using eth5. Grab the hardware address of the interface. Let’s imagine that’s 01:23:45:67:89:ab in our case.

Now, execute dlpiping in server mode.

root@host1# /opt/VRTSllt/dlpiping -vs eth5
using packet size = 78
dlpiping: binding ping SAP 0xf00e

Now, on the host you want to test connectivity from, send a request!

root@host2# /opt/VRTSllt/dlpiping -vc eth5 01:23:45:67:89:ab
using packet size = 78
dlpiping: sent a request to 01:23:45:67:89:ab
dlpiping: received a packet from 01:23:45:67:89:ab
01:23:45:67:89:ab is alive

Hooray! On your first host, you’ll see a response pop up, too.

dlpiping: sent a response

This is an invaluable tool in troubleshooting those times when your cluster just won’t come up, no matter what you do! This will give you reassurance that at least your network is working. Or alternatively, confirmation that you’ve got lower level issues!