SNAP PAC devices receiving long 802.1Q VLAN broadcasts may have communication failures

Applies To:

SNAP-PAC-S1
SNAP-PAC-S2
SNAP-PAC-R1
SNAP-PAC-R2
SNAP-PAC-S1-W
SNAP-PAC-S2-W
SNAP-PAC-R1-W
SNAP-PAC-R2-W

Versions Affected:

In all versions up to and including version: R8.5a
Resolution is included beginning in version: B8.5b
Problem is fixed in version: R8.5c

Resolved In Version:

Problem is fixed in version: R8.5c

Symptoms:

If an affected SNAP PAC device is connected to an Ethernet segment that carries IEEE 802.1Q VLAN traffic, it may become unresponsive to Ethernet communication.

The IEEE 802.1Q standard increased the maximum Ethernet fram size from 1518 bytes to 1522 bytes to accommodate the VLAN tag. If any frames longer than 1518 bytes are received by an affected SNAP PAC device, memory corruption occurs.

Workaround:

Disable 802.1Q VLAN for the 802.1Q compatible switch port to which the SNAP PAC devices are attached. By doing so, the SNAP PAC devices do not receive VLAN tagged messages.

Questions?

Contact: Opto 22 Product Support.
Phone: 800-835-6786 or 951-695-3080
Email: support@opto22.com

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