Troubleshooting; Vlans - HP ProCurve 2810 Series Management And Configuration Manual

Port Status and Basic Configuration
Jumbo Packets
10-22
Jumbo-Enabled VLAN
VLAN 10
Port 3 belongs to both VLAN 10 and VLAN 20.
Jumbo packets received inbound on port 3 can be
forwarded out the Non-Jumbo ports 4, 5, and 6.
Figure 10-13. Forwarding Jumbo Packets Through Non-Jumbo Ports
Jumbo packets can also be forwarded out non-jumbo ports when the
jumbo packets received inbound on a jumbo-enabled VLAN are routed to
another, non-jumbo VLAN for outbound transmission on ports that have
no memberships in other, jumbo-capable VLANs. Where either of the
above scenarios is a possibility, the downstream device must be config­
ured to accept the jumbo traffic. Otherwise, this traffic will be dropped
by the downstream device.

Troubleshooting

A VLAN is configured to allow jumbo packets, but one or more ports
drops all inbound jumbo packets. The port may not be operating at 1
gigabit or higher. Regardless of a port's configuration, if it is actually operating
at a speed lower than 1 gigabit, it drops inbound jumbo packets. For example,
if a port is configured for Auto mode (speed-duplex auto), but has negotiated a
100 Mbps speed with the device at the other end of the link, then the port
cannot receive inbound jumbo packets. To determine the actual operating
speed of one or more ports, view the Mode field in the output for the following
command:
show interfaces brief < port-list >
A non-jumbo port is generating "Excessive undersize/giant packets"
messages in the Event Log. The switch can transmit outbound jumbo traf­
fic on any port, regardless of whether the port belongs to a jumbo VLAN. In
this case, another port in the same VLAN on the switch may be jumbo-enabled
through membership in a different, jumbo-enabled VLAN, and may be forward­
ing jumbo packets received on the jumbo VLAN to non-jumbo ports. Refer to
"Outbound Jumbo Traffic" on page 10-21.
1 2 3 4 5 6
Non-Jumbo VLAN
VLAN 20