Using vxrlink to diagnose packet-related network issues

Article:HOWTO64294  |  Created: 2011-12-29  |  Updated: 2012-01-12  |  Article URL http://www.symantec.com/docs/HOWTO64294
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Using vxrlink to diagnose packet-related network issues

If you have selected the UDP transport protocol for replication, the UDP packet size used by Veritas Volume Replicator (VVR) to communicate between hosts could be an important factor in the replication performance. By default, VVR uses a UDP packet size of 8400 bytes. In certain network environments, such as those that do not support fragmented IP packets, it might be necessary to decrease the packet size.

If the network you are using loses many packets, the effective bandwidth available for replication is reduced. You can tell that this is happening if you run the vxrlink stats command on the RLINK and see many timeout errors. In this case, network performance might be improved by reducing the packet size. If the network is losing many packets, it can simply be that each time a large packet is lost, a large retransmission has to take place. In this case, try reducing the packet size until the problem is ameliorated.

If some element in the network, such as IPSEC or VPN hardware, is adding extra data to the packets, reduce the packet size so that there is space for the additional bytes in the packet, and the MTU is not exceeded. Otherwise, each packet is broken into two.

See Using vxrlink to diagnose network issues


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