Interface And Hardware Component Configuration Guide For Cisco Ncs 5500 Series Routers, Ios Xr Release - Cisco NCS 5500 Series Configuration Manual

Ethernet MTU
• MTU discovery process determines largest packet size–This process is available for all IPV6 devices,
and for originating IPv4 devices. In this process, the originating IP device determines the size of the
largest IPv6 or IPV4 packet that can be sent without being fragmented. The largest packet is equal to
the smallest MTU of any network between the IP source and the IP destination devices. If a packet is
larger than the smallest MTU of all the networks in its path, that packet will be fragmented as necessary.
This process ensures that the originating device does not send an IP packet that is too large.
Jumbo frame support is automatically enable for frames that exceed the standard frame size. The default value
is 1514 for standard frames and 1518 for 802.1Q tagged frames. These numbers exclude the 4-byte frame
check sequence (FCS).

Interface and Hardware Component Configuration Guide for Cisco NCS 5500 Series Routers, IOS XR Release

6.1.x
22
Configuring Ethernet Interfaces