Observe the following general rules when planning your physical MTU configurations:
The 7210 SAS must contend with MTU limitations at many service points. The physical (access and access uplink) port, MTU values must be individually defined.
Identify the ports that are designated as access uplink ports as these are intended to carry service traffic.
MTU values should not be modified frequently.
The access uplink port MTU on the 7210 SAS-D and 7210 SAS-Dxp must be greater than or equal to the access port MTU plus the overhead added by the system (for example, typically 4 bytes of VLAN tag are added when a packet is transmitted using the QinQ access uplink).
The 7210 SAS-K 2F1C2T supports service-mtu. The service MTU values must conform to the following conditions:
The service MTU must be less than or equal to the access-uplink port MTU.
The service MTU must be less than or equal to the access port (SAP) MTU.
The 7210 SAS-K 2F6C4T and 7210 SAS-K 3SFP+ 8C support service-mtu. The service MTU values must conform to the following conditions:
The service MTU must be less than or equal to the access-uplink port MTU.
The service MTU must be less than or equal to the SDP path MTU when the service is configured to use MPLS SDPs.
The service MTU must be less than or equal to the access port (SAP) MTU.