Configuring The Mtu Size For Bridged Ethernet - Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - LINK LAYER CONFIGURATION GUIDE 2010-10-13 Configuration Manual

Configuring the MTU Size for Bridged Ethernet

bridge1483 mtu
Copyright © 2010, Juniper Networks, Inc.
This section provides an example for configuring PPPoE interfaces over S-VLAN
subinterfaces configured on bridged Ethernet. For descriptions of the commands used
in this procedure, see "Configuring Higher-Level Protocols over VLANs" on page 453.
To configure PPPoE over S-VLAN over a bridged Ethernet interface:
Follow the steps in "Configuring S-VLAN Subinterfaces over Bridged Ethernet" on
1.
page 457 to configure the S-VLAN subinterface.
Create a PPPoE major interface on the S-VLAN subinterface.
2.
host1(config-subif)#pppoe
Exit the subinterface context.
3.
host1(config-subif)#exit
Create a PPPoE subinterface by adding a subinterface number to the interface
4.
identification command.
host1(config)#pppoe subinterface atm 3/1.1.1.1
Specify PPP as the encapsulation method on the interface.
5.
host1(config-subif)#encapsulation ppp
Assign an IP address and mask to the interface.
6.
host1(config-subif)#ip address 10.1.2.3 255.255.255.255
You can use the bridge1483 mtu command to configure a nondefault maximum
transmission unit (MTU) size, in bytes, for a bridged Ethernet interface. The default MTU
size for a bridged Ethernet interface is 1518 bytes.
Because you configure a bridged Ethernet interface over an ATM 1483 subinterface, the
MTU size set with the bridge1483 mtu command is limited by the MTU set for the
underlying ATM 1483 subinterface. As a result, the bridge1483 mtu command requires
you to configure an MTU size for the bridged Ethernet interface that does not exceed
the maximum allowable MTU size for the underlying ATM 1483 subinterface, 9180 bytes.
The configured MTU size for an interface is referred to as its administrative MTU, and the
MTU size at which the interface actually operates is referred to as its operational MTU.
For bridged Ethernet interfaces, the operational MTU is the lesser of the following two
values:
The administrative MTU of the bridged Ethernet interface
The administrative MTU of the underlying ATM 1483 subinterface
You can also use the bridge1483 mtu command in a profile to configure a nondefault
MTU size for a dynamic bridged Ethernet interface. For information, see "Configuring a
Dynamic Interface from a Profile" on page 559 in "Configuring Dynamic Interfaces" on
page 511.
Chapter 14: Configuring Bridged Ethernet
459