MTU parameters must be modified on the service level as well as the port level.
The service-level MTU parameters configure the service payload (Maximum Transmission Unit – MTU) in bytes for the service ID overriding the service-type default MTU.
The port-level MTU parameters configure the maximum payload MTU size for an Ethernet port or SONET/SDH SONET path (sub-port) or TDM port/channel, or a channel that is part of a multilink bundle or LAG.
The default MTU values must be modified to ensure that packets are not dropped because of frame
size limitations. The service MTU must be less than or equal to both the SAP port MTU
and the SDP path MTU values. When an SDP is configured on a network port using default
port MTU values, the operational path MTU can be less than the service MTU. In this
case, enter the show service sdp command to check the operational
state. If the operational state is down, then modify the MTU value accordingly.