IP Fragmentation with Jumbo Frames

Summit series switches support fragmentation of IP packets. The above support is included whether or not the switches are present in a SummitStack.

ExtremeXOS supports the fragmenting of IP packets. If an IP packet originates in a local network that allows large packets and those packets traverse a network that limits packets to a smaller size, the packets are fragmented instead of discarded.

This feature is designed to be used in conjunction with jumbo frames. Frames that are fragmented are not processed at wire-speed within the switch fabric.

Note

Jumbo frame-to-jumbo frame fragmentation is not supported. Only jumbo frame-to-normal frame fragmentation is supported.

Enable jumbo frames on the incoming port.
Add the port to a VLAN (Virtual LAN).
Assign an IP address to the VLAN.
Enable ipforwarding on the VLAN.
Set the MTU size for the VLAN.
configure ip-mtu mtu vlan vlan_name

The ip-mtu value ranges between 1500 and 9194, with 1500 the default. However, CLI will allow the maximum limit up to 9216 considering port configuration such as tagging which influences L2 Header size. But the values greater than 9194 may lead to packet loss and hence not recommended.
Note
To set the MTU size greater than 1500, all ports in the VLAN must have jumbo frames enabled.

Published March 2020prev | next

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