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.

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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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