Juniper EX2200 Hardware Manual page 231

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Copyright © 2015, Juniper Networks, Inc.
NOTE:
The MTU for an IRB interface is calculated by removing the Ethernet header
overhead [6(DMAC)+6(SMAC)+2(EtherType)]. Becase, the MTU is the lower
value of the MTU configured on the IRB interface and the MTU configured on
the IRB's associated bridge domain IFDs or IFLs, the IRB MTU is calculated
as follows:
In case of Layer 2 IFL configured with the
the IRB MTU is calculated by including 8 bytes overhead (SVLAN+CVLAN).
In case of Layer 2 IFL configured with the
MTU is calculated by including a single VLAN 4 bytes overhead.
NOTE: If a packet whose size is larger than the configured MTU size is received
on the receiving interface, the packet is eventually dropped. The value
considered for MRU (maximum receive unit) size is also the same as the MTU
size configured on that interface.
NOTE: Not all devices allow you to set an MTU value, and some devices have
restrictions on the range of allowable MTU values. You cannot configure an
MTU for management Ethernet interfaces (fxp0, em0, or me0) or for
loopback, multilink, and multicast tunnel devices.
For more information about configuring MTU for specific interfaces and router or switch
combinations, see "Configuring the Media MTU" on page
—MTU size.
bytes
Range: 256 through 9192 bytes, 256 through 9216 (EX Series switch interfaces), 256
through 9500 bytes (Junos OS 12.1X48R2 for PTX Series routers)
Default: 1500 bytes (INET, INET6, and ISO families), 1448 bytes (MPLS), 1514 bytes (EX
Series switch interfaces)
interface—To view this statement in the configuration.
interface-control—To add this statement to the configuration.
Chapter 3: Configuration Statements
flexible-vlan-tagging statement,
statement, the IRB
vlan-tagging
53.
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