You can configure a unique MTU value for each Fabric Extend (FE) tunnel on a XA1400 Series device. You can configure each ISIS logical interface with a unique MTU value for each FE tunnel in the VXLAN interface to improve fragmentation and reassembly in WAN connectivity over MPLS IP VPN and internet-based connections through a NAT router.
Fragmentation and reassembly is based on the MTU value configured for each FE tunnel. You can change the MTU configuration at any time for each FE tunnel. The supported MTU range is 750 to 9000, and the default MTU value is 1950.
Note
FE Tunnel MTU is an optional configuration.
For example, if you configure an FE tunnel with an MTU of 900, and a packet size of 1950 is received on UNI with the destination on the FE tunnel, the system fragments the original 1950-sized packet into the three packets (900, 900, 150) with a packet size equal to or less than 900. The system transmits the three fragmented packets over the ISIS logical interface of the FE tunnel. After the packets are received at the destination, the system performs the packet reassembly (900, 900, 150) into the 1950-sized packet.
If route MTU is not configured, the MTU value for each FE tunnel is applicable to ingress and egress traffic on the tunnel.
Note
System MTU maximum is a separate configuration. You can configure a system maximum MTU size of 1522, 1950, or 9022. The default value is 1950.