Limiting PMTU

You can limit calculated PMTU values within a range by using the tcp path-mtu-discovery max-mtu and tcp path-mtu-discovery min-mtu commands. When specifying PMTU limits, keep the following in mind:

• If a PMTU discovery value is lower than the configured minimum MTU setting, PMTU discovery is disabled for that connection.
• If a PMTU discovery value is larger than the configured maximum MTU setting, the configured maximum MTU setting is used.
• The maximum MTU setting must be greater than the minimum MTU setting.

tcp path-mtu-discovery max-mtu

• Use to limit the maximum MTU size used for the path MTU.
• Example

  host1:VR1(config)#tcp path-mtu-discovery max-mtu 512

• Use the no version to remove any limitation so that the virtual router uses the path MTU discovery value.
• See tcp path-mtu-discovery

tcp path-mtu-discovery min-mtu

• Use to specify the minimum MTU value used for the path MTU. If the discovered PMTU value is less than the minimum setting, path MTU discovery is disabled for this connection.
• Example

  host1:VR1(config)#tcp path-mtu-discovery min-mtu 255

• Use the no version to remove any limitation so that the virtual router uses the discovered path MTU value.
• See tcp path-mtu-discovery

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