Interface Configuration
7750 SR Interface Configuration Guide Page 171
Since ALA-A uses Dot1q encapsulation, the SAP MTU must be set to 1518 to be able to accept a
1514 byte service frame (see Table 27 for MTU default values). Each SDP MTU must be set to at
least 1514 as well. If ALA-A’s network port (2/1/1) is configured as an Ethernet port with a GRE
SDP encapsulation type, then the MTU value of network ports 2/1/1 and 3/1/1 must each be at
least 1556 bytes (1514 MTU + 28 GRE/Martini + 14 Ethernet). Finally, the MTU of ALA-B’s
SAP (access port 4/1/1) must be at least 1514, as it uses null encapsulation.
Port (slot/MDA/port) 1/1/1 2/1/1 3/1/1 4/1/1
Mode type dot1q network network null
MTU 1518 1556 1556 1514
Table 28: MTU Configuration Example Values (Continued)