What is the minimum Ethernet physical network MTU required for a Layer 2 service on an MPLS encapsulated SDP with a service MTU of 1500?

For an Ethernet L2 service carried over an MPLS SDP, the port MTU must accommodate the customer frame plus two MPLS headers (2 × 4 B) and the provider Ethernet header (14 B). 1500 + 8 + 14 = 1522 bytes, so 1522 is the minimum physical network MTU.

A. Omits 22 B of provider overhead—too small.
B. Ignores the outer Ethernet header—undersized.
C. Still misses 8 B of MPLS label stack.

1. Nokia SR OS Services Guide 20.10, sec 3 “Service MTU Calculation”, Table 12, p. 198.

2. Nokia SR OS MPLS Guide 20.10, sec 2.1 “Encapsulation Overheads”, p. 67.

3. Stanford EE 384 “High-Performance Networking”, lecture 14 notes, slide 7 “MPLS Ethernet overhead”.