Amer Networks E5Web GUI - Manual (Page 711)

so that it is unique (the default value is 0). The Cluster ID determines that the MAC address for
the cluster is unique.
• Enabling the advanced setting Use Unique Share MAC is recommended so that each interface
has its own MAC address. If this is not enabled, interfaces share a MAC address and this can
confuse some third party switches.
• Make sure that the advanced setting High Buffers is set to be automatic for both units in the
cluster. This setting determines how memory is allocated by cOS Core for handling increasing
numbers of connections. A cOS Core restart is required for a change in this setting to take
effect and this can be achieved with the CLI command:
Device:/> shutdown
Where a cluster has a very high number (for example, tens of thousands) of simultaneous
connections then it may be necessary to set a high value for this instead of enabling the
Dynamic High Buffers option. A very high value for High Buffers can suit situations with large
numbers of connections but can have the disadvantage of increasing throughput.
See Section 12.10, “Miscellaneous Settings” for a full explanation of these settings.
11.3.5. Unique Shared Mac Addresses
For HA setup, cOS Core provides the advanced option Use Unique Shared MAC Address. By default,
this is enabled and in most configurations it should not need to be disabled.
Enabling a Unique Shared MAC Address
The effect of enabling this setting is that a single, unique MAC address will be used for each pair
of matching hardware interfaces so that, for example, the lan1 interface on the master unit will
appear to have the same MAC address as the lan1 interface on the slave unit.
Problem Diagnosis
An HA cluster will function if this setting is disabled but can cause problems with a limited
number of switch types where the switch uses a shared ARP table. Such problems can be hard to
diagnose which is why it is best to always have the setting enabled.
With Dissimilar Hardware Units
In one situation, this setting should be disabled and that is when an HA cluster is set up using
non-matching hardware. In order to function correctly, unique shared MAC addresses should not
be used. For this reason, the setup wizard asks if non-matching hardware is being used and
adjusts this setting appropriately.
Chapter 11: High Availability
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