Enabling jumbo frames to increase the mirroring path MTU
On 1-Gbps and 10-Gbps ports in the mirroring path, you can reduce the number of dropped frames by enabling
jumbo frames on all intermediate switches and routers. (The MTU on the switches covered by this manual is 9220
bytes for frames having an 802.1Q VLAN tag, and 9216 bytes for untagged frames.)
Table 30: Maximum frame sizes for mirroring
Frame type
configuration
Maximum
frame size
VLAN tag Frame
mirrored
to local
port
Frame mirrored to remote
port
Data Data IPv4 header
Untagged Non-jumbo (default
config.)
1518 0 1518 1464 54
Jumbo on all VLANs 9216 0 9216 9162 54
Jumbo
11
On all but
source VLAN
1518 0 n/a 1464 54
Tagged Non-jumbo 1522 4 1522 1468 54
Jumbo
11
on all VLANs 9220 4 9218 9164 54
Jumbo
11
On all but
source VLAN
1522 4 n/a
22
1468 54
1
Jumbo frames are allowed on ports operating at or above 1 Gbps
2
For local mirroring, a non-jumbo configuration on the source VLAN dictates an MTU of 1518 bytes for untagged frames, and
an MTU of 1522 for tagged frames, regardless of the jumbo configuration on any other VLANs on the switch.
Effect of downstream VLAN tagging on untagged,
mirrored traffic
In a remote mirroring application, if mirrored traffic leaves the switch without 802.1Q VLAN tagging, but is
forwarded through a downstream device that adds 802.1Q VLAN tags, the MTU for untagged mirrored frames
leaving the source switch is reduced below the values shown in
Maximum frame sizes for mirroring.
444 Aruba 2930F / 2930M Management and Configuration Guide
for ArubaOS-Switch 16.08
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