12-2
Port Traffic Controls
Overview
Overview
This chapter includes:
■ Jumbo Frames: Enables ports operating at 1 Gbps or 10 Gbps speeds to
accept inbound frames of up to 9220 bytes when configured for jumbo
traffic.
Jumbo Frames
The Maximum Transmission Unit (MTU) is the maximum size IP frame the
switch can receive for Layer 2 frames inbound on a port. The switch drops any
inbound frames larger than the MTU allowed on the port. On ports operating
at 10 Mbps or 100 Mbps, the MTU is fixed at 1522 bytes. However, ports
operating at 1 Gbs or 10 Gbps speeds accept forward frames of up to 9220
bytes (including four bytes for a VLAN tag) when configured for jumbo traffic.
You can enable inbound jumbo frames on a per-VLAN basis. That is, on a VLAN
configured for jumbo traffic, all ports belonging to that VLAN and operating
at 1 Gbs or 10 Gbps allow inbound jumbo frames of up to 9220 bytes.
(Regardless of the mode configured on a given jumbo-enabled port, if the port
is operating at only 10 Mbps or 100 Mbps, only frames that do not exceed 1522
bytes are allowed inbound on that port.)
Terminology
Jumbo Frame: An IP frame exceeding 1522 bytes in size. The maximum
Jumbo frame size is 9220 bytes. (This size includes 4 bytes for the VLAN
tag.)
Feature Default Menu CLI Web
Jumbo Packets Disabled n/a 12-2 n/a
Feature Default Menu CLI Web
display VLAN jumbo status n/a — 12-5 —
configure jumbo VLANs Disabled — 12-7 —
