Veritas Volume Replicator (VVR) uses a number of memory slots on the Secondary site to store incoming network I/O. By default, number of messages slots is 1024. If the network has high packet reordering, the default number of message slots may not be enough. Packets will get dropped if they are out of order, and this will impact replication performance.

You can examine extended RLINK statistics from vxrlink -e stats command output to find packet reordering:

# vxrlink -g dg1 -i10 -e stats rlink1
Errors :
 ------
 No memory available                             : 0
 No message slots available                      : 0
 No memory available in nmcom pool on Secondary  : 0
 Timeout                                         : 0
 Missing packet                                  : 0
 Missing message                                 : 0
 Stream                                          : 0
 Checksum                                        : 0
 Unable to deliver due to transaction            : 0

Errors in the following categories indicate that packet reordering is happening in the network:

If you determined that your network has an issue with packet reordering, you must increase the number of message slots.

See Resolving packet reordering.

See Using vxrlink to diagnose network issues