Table 18: Encapsulation Overhead By Encapsulation Type - Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual

JUNOS 10.1 Network Interfaces Configuration Guide
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
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

Table 18: Encapsulation Overhead by Encapsulation Type

116
Configuring the Media MTU
this PIC: 9018
this PIC: 1518
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)
Ethernet over ATM
Ethernet SNAP
Ethernet translational cross-connect (TCC)
Ethernet version 2
Extended virtual local area network (VLAN) CCC and VPLS
Extended VLAN TCC
Frame Relay
PPP
Encapsulation Overhead (Bytes)
21
26
18
4
12
4
17
4
32
22
18
14
4
22
4
4