User Guide

PMP 450 Planning Guide
Translation bridging
Optionally, you can configure the AP to change the source MAC address in every packet it receives from its
SMs to the MAC address of the SM that bridged the packet, before forwarding the packet toward the public
network. If you do, then
• not more than 10 IP devices at any time are valid to send data to the AP from behind the SM.
• the AP populates the Translation Table tab of its Statistics web page, displaying the MAC address and IP
address of all the valid connected devices.
• each entry in the Translation Table is associated with the number of minutes that have elapsed since the
last packet transfer between the connected device and the SM.
• if 10 are connected, and another attempts to connect
o and no Translation Table entry is older than 255 minutes, the attempt is ignored.
o and an entry is older than 255 minutes, the oldest entry is removed and the attempt is successful.
• the Send Untranslated ARP parameter in the General tab of the Configuration page can be
o disabled, so that the AP will overwrite the MAC address in Address Resolution Protocol (ARP)
packets before forwarding them.
o enabled, so that the AP will forward ARP packets regardless of whether it has overwritten the MAC
address.
This is the Translation Bridging feature, which you can enable in the General tab of the Configuration web page
in the AP. When this feature is disabled, the setting of the Send Untranslated ARP parameter has no effect,
because all packets are forwarded untranslated (with the source MAC address intact).
See Address Resolution Protocol on Page 1-122.
Engineering VLANs
The radios support VLAN functionality as defined in the 802.1Q (Virtual LANs) specification, except for the
following aspects of that specification:
• the following protocols:
o Generic Attribute Registration Protocol (GARP) GARV
o Spanning Tree Protocol (STP)
o Multiple Spanning Tree Protocol (MSTP)
o GARP Multicast Registration Protocol (GMRP)
• embedded source routing (ERIF) in the 802.1Q header
• multicast pruning
• flooding unknown unicast frames in the downlink
As an additional exception, the AP does not flood downward the unknown unicast frames to the SM.
A VLAN configuration in Layer 2 establishes a logical group within the network. Each computer in the VLAN,
regardless of initial or eventual physical location, has access to the same data. For the network operator, this
provides flexibility in network segmentation, simpler management, and enhanced security.
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pmp-0047 (March 2014)