The MTU implementations are different on vendor’s equipments, different equipments, different boards and even different software on the same hardware platform. Most of the known and used MTU are the following: Physical MTU, IP MTU, GRE IP MTU, IPSEC MTU, MPLS MTU, MPLS TE MTU, and LDP over MPLS TE MTU. The packet/frame verification and fragmentation can be done or in ingress or in egress depending of course of the implementation on specific device and vendor.

Theoretically we have the following MTU for an Ethernet frame, with the following relationship between them:

ETHERNET MTU > MPLS MTU > IP MTU

ETHERNET MTU = ETHERNET ENCAPSULATION + MPLS MTU + IP MTU

Ethernet, Carrier and Datacenter Ethernet Protocol Overhead and Throughput

Let’s start to calculate the Protocol Overhead, Protocol Efficiency and Throughput for Ethernet, Carrier and Datacenter Ethernet Protocols like 802.3, 802.1q, 802.1ad QinQ, 802.1ah mac-in-mac, MPLS, TRILL. More information about the Ethernet frame formats and fields’ description, Protocols Overhead and the table representing all can be found in my previous post Ethernet and Overlay technologies over Ethernet .