Issue:

It is becoming more common for customers to configure Low Latency Transport (LLT) over UDP network links rather than using the DLPI protocol historically used by LLT.

Note that all configurations specific to LLT over UDP takes place in /etc/llttab. All other configuration files related to LLT (i.e. /etc/llthosts) configuration stay consistent whether using UDP or DLPI.

Solution:

This document gives an example of configuring two Solaris machines running Veritas Cluster Server (VCS) and LLT 5.0 maintenance pack 3 (5.0MP3) to use LLT over UDP. Note that in this example:

The machines are on different subnets
All links (low and high priority) use LLT over UDP

 

Note that it is supported to have a mix of DLPI and UDP links (i.e. one high priority link usingDLPI with another using UDP)
Note that it is also supported to use bonded or aggregated network cards in an LLT over UDP configuration.

/etc/llttab from node 0:

set-node cbuckwell
set-cluster 19919
link qfe2 /dev/udp - udp 60002 - 10.12.242.127 10.12.247.255
set-addr 1 qfe2 10.12.251.126  
link eri0 /dev/udp - udp 60001 - 10.12.240.204 10.12.247.255
set-addr 1 eri0 10.12.251.84
link-lowpri qfe3 /dev/udp - udp 60003 - 192.168.2.1 192.168.2.255
set-addr 1 qfe3 192.168.2.2

exclude 2-31
set-bcasthb 0
set-arp 0
set-strictsrc 0

/etc/llttab from node 1:

set-noderdgt2000-05
set-cluster 19919
link e1000g1 /dev/udp - udp 60002 - 10.12.251.126 10.12.255.255
set-addr 0 e1000g1 10.12.242.127
link e1000g0 /dev/udp - udp 60001 - 10.12.251.84 10.12.255.255
set-addr 0 e1000g0 10.12.240.204
link-lowpri e1000g2 /dev/udp - udp 60003 - 192.168.2.2 192.168.2.255
set-addr 0 e1000g2 192.168.2.1

exclude 2-31
set-bcasthb0
set-arp 0
set-strictsrc 0

Note that in the above example:

- The set-addr line following each 'link' line gives the IP address of the corresponding link on a remote node hence providing a distinct end point for each LLT link.

Each 'set-addr' line contains a node id (second field) which represents the remove node as per /etc/llthosts to which the set-addr line refers.

Each 'set-addr' line also has a network card name (third field) which represents the local link definition to which the set-addr line applies.

For example the following set-addr lines would indicate that the local link using e1000g0 should attempt to communicate with node 0 using IP address 10.12.240.204 and node 2 with IP address 10.12.240.206.As such we can see that there should be a separate set-addr line for each remote node against each local link.

set-addr  0 e1000g0 10.12.240.204
set-addr  2 e1000g0 10.12.240.206

- It is required to include 'set-strictsrc 0' due to the nodes being on different subnets. Without this LLT does not function as expected.