Table 202: Media Mtu Sizes By Interface Type For Ex Series Switches; Table 203: Encapsulation Overhead By Encapsulation Type - Juniper JUNOS OS 10.4 - FOR EX REV 1 Manual

Copyright © 2010, Juniper Networks, Inc.
NOTE: On Gigabit Ethernet ePIMs in J4350 and J6350 Services Routers, you
can configure a maximum transmission unit (MTU) size of only 9018 bytes
even though the CLI indicates that you can configure an MTU of up to 9192
bytes. If you configure an MTU greater than 9018 bytes, the router does not
accept the configuration and generates a system log error message similar
to the following:
/kernel: ge-0/0/0: Illegal media change. MTU invalid: 9192. Max MTU
supported on this PIC: 9018
On 4-port Fast Ethernet ePIMs in J4350 and J6350 Services Routers, you can
configure a maximum transmission unit (MTU) size of only 1518 bytes even
though the CLI indicates that you can configure an MTU of up to 9192 bytes.
If you configure an MTU greater than 1518 bytes, the router does not accept
the configuration and generates a system log error message similar to the
following:
/kernel: fe-3/0/1: Illegal media change. MTU invalid: 9192. Max MTU
supported on this PIC: 1518

Table 202: Media MTU Sizes by Interface Type for EX Series Switches

Default Media
Interface Type MTU (Bytes)
Gigabit Ethernet 1514
10-Gigabit Ethernet 1514

Table 203: Encapsulation Overhead by Encapsulation Type

Interface Encapsulation
802.1Q/Ethernet 802.3
802.1Q/Ethernet Subnetwork Access Protocol (SNAP)
802.1Q/Ethernet version 2
ATM Cell Relay
ATM permanent virtual connection (PVC)
Cisco HDLC
Ethernet 802.3
Ethernet circuit cross-connect (CCC) and virtual private
LAN service (VPLS)
Chapter 58: Configuring Interfaces
Maximum MTU Default IP Protocol
(Bytes) MTU (Bytes)
9192 1500 (IPv4), 1497
(ISO)
9192 1500 (IPv4), 1497
(ISO)
Encapsulation Overhead (Bytes)
21
26
18
4
12
4
17
4
1311