Management and Configuration Guide K/KA/KB.15.15

you remove a port from a jumbo-enabled VLAN, the switch
disables jumbo traffic capability on the port only if the port is
not currently a member of another jumbo-enabled VLAN. This
same operation applies to port trunks.
Jumbo traffic sources A port belonging to a jumbo-enabled VLAN can receive inbound
jumbo frames through any VLAN to which it belongs, including
non-jumbo VLANs. For example, if VLAN 10 (without jumbos
enabled) and VLAN 20 (with jumbos enabled) are both
configured on a switch, and port 1 belongs to both VLANs, port
1 can receive jumbo traffic from devices on either VLAN.
Operating notes for jumbo traffic-handling
• HP Switch does not recommend configuring avoice VLAN to accept jumbo frames. Voice
VLAN frames are typically small, and allowing a voice VLAN to accept jumbo frame traffic
can degrade the voice transmission performance.
• You can configure the default, primary, and/or (if configured) the management VLAN to
accept jumbo frames on all ports belonging to the VLAN.
• When the switch applies the default MTU (1522-bytes including 4 bytes for the VLAN tag) to
a VLAN, all ports in the VLAN can receive incoming frames of up to 1522 bytes. When the
switch applies the jumbo MTU (9220 bytes including 4 bytes for the VLAN tag) to a VLAN,
all ports in that VLAN can receive incoming frames of up to 9220 bytes. A port receiving
frames exceeding the applicable MTU drops such frames, causing the switch to generate an
Event Log message and increment the "Giant Rx" counter (displayed by show interfaces
<port-list>.)
• The switch allows flow control and jumbo frame capability to co-exist on a port.
• The default MTU is 1522 bytes (including 4 bytes for the VLAN tag.) The jumbo MTU is 9220
bytes (including 4 bytes for the VLAN tag.)
• When a port is not a member of any jumbo-enabled VLAN, it drops all jumbo traffic. If the
port is receiving "excessive"inbound jumbo traffic, the port generates an Event Log message
to notify you of this condition. This same condition also increments the switch's "Giant Rx"
counter.
• If you do not want all ports in a given VLAN to accept jumbo frames, you can consider creating
one or more jumbo VLANs with a membership comprising only the ports you want to receive
jumbo traffic. Because a port belonging to one jumbo-enabled VLAN can receive jumbo frames
through any VLAN to which it belongs, this method enables you to include both jumbo-enabled
and non-jumbo ports within the same VLAN.
For example, suppose you want to allow inbound jumbo frames only on ports 6, 7, 12, and
13. However, these ports are spread across VLAN 100 and VLAN 200 and also share these
VLANs with other ports you want excluded from jumbo traffic. A solution is to create a third
VLAN with the sole purpose of enabling jumbo traffic on the desired ports, while leaving the
other ports on the switch disabled for jumbo traffic. That is:
VLAN 300VLAN 200VLAN 100
6, 7, 12, and 1311-156-10Ports
YesNoNoJumbo-enabled
If there are security concerns with grouping the ports as shown for VLAN 300, you can either
use source-port filtering to block unwanted traffic paths or create separate jumbo VLANs, one
for ports 6 and 7, and another for ports 12 and 13.
Jumbo frames 193