Cambium Networks PMP 450d Series, Руководство пользователя

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Chapter 3: System planning Data network planning
Page 3-31
Translation bridging
Optionally, the AP can be configured to change the source MAC address in every packet it receives
from its SMs to the MAC address of the SM/BHS that bridged the packet, before forwarding the
packet toward the public network. In this case:
 Not more than 128 IP devices at any time are valid to send data to the AP from behind the SM.

SM 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 128 are connected, and another attempts to connect:
o
If no Translation Table entry is older than 255 minutes, the attempt is ignored.
o
If 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 overwrites the MAC address in ARP packets before forwarding
them.
o
Enabled, so that the AP forwards ARP packets regardless of whether it has overwritten the
MAC address.
This is the Translation Bridging feature, which you can enable in the General page 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 3-29 .
Engineering VLANs
The radios support VLAN functionality as defined in the 802.1Q (Virtual LANs) specification, except
for the following aspects of that specification:

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/BHM does not flood downward the unknown unicast frames to
the SM/BHS.
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.