HP 2600 - Manual (Page 188)

Port Status and Basic Configuration
Jumbo Packets on the Series 2800 Switches
Enabling or Disabling Jumbo Traffic on a VLAN
Syntax: vlan < vid > jumbo
[ no ] vlan < vid > jumbo
Configures the specified VLAN to allow jumbo packets on all
ports on the switch that belong to that VLAN. If the VLAN is
not already configured on the switch,
vlan < vid > jumbo also
creates the VLAN. Note that a port belonging to one jumbo
VLAN can receive jumbo packets through any other VLAN
statically configured on the switch, regardless of whether the
other VLAN is enabled for jumbo packets. The
[no] form of the
command disables inbound jumbo traffic on all ports in the
specified VLAN that do not also belong to another VLAN that
is enabled for jumbo traffic. In a VLAN context, the command
forms are
jumbo and no jumbo. (Default: Jumbos disabled on
the specified VLAN.)
Operating Notes for Jumbo Traffic-Handling
■ HP does not recommend configuring a voice VLAN to accept jumbo
packets. Voice VLAN packets are typically small, and allowing a voice
VLAN to accept jumbo packet traffic can degrade the voice transmission
performance.
■ You can configure the default, primary, and/or (if configured) the manage­
ment VLAN to accept jumbo packets on all ports belonging to the VLAN.
■ When the switch applies the default MTU (1522-bytes) to a VLAN, all ports
in the VLAN can receive incoming packets of up to 1522 bytes in length.
When the switch applies the jumbo MTU (9220 bytes) to a VLAN, all ports
in that VLAN can receive incoming packets of up to 9220 bytes in length.
A port receiving packets exceeding the applicable MTU drops such pack­
ets, causing the switch to generate an Event Log message and increment
the “Giant Rx” counter (displayed by
show interfaces < port-list >).
■ The switch does not allow flow control and jumbo packet capability to
co-exist on a port. Attempting to configure both on the same port gener­
ates an error message in the CLI and sends a similar message to the Event
Log.
■ The default MTU on the Series 2800 switches is 1522 bytes (including 4
bytes for the VLAN tag). The jumbo MTU is 9220 bytes (including 4 bytes
for the VLAN tag).
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