Best practice - Additional configuration for quiet clients behind mesh link bridge

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Examine the following topology, as it is a less frequently used design for remote bridged networks

In some use cases, it may be required or desired to bridge remote wired or wireless devices to a primary network by means of an AP connecting via Mesh and bridging its ethernet port. This has been seen on the educational market when using "portable classrooms" that are disconnected from the main building, or for trailers containing equipment that do not have a hard wired connection to the primary network.

In order for the clients behind the bridge-access port of a mesh AP to maintain a reliable connection, the mesh AP must maintain a list of MAC addresses that are connected below it. This not only allows the AP to route traffic from the clients over the mesh to the primary network, but also to advertise the presence of these clients over the mesh to the Portal access point; this component is necessary for traffic to be forwarded properly.

When connecting to the bridge-access port of a mesh point, one must consider a different form of a "quiet client" syndrome in where specific users may not send any traffic upstream over the mesh link for an extended period of time.
a.) Power-save clients
b.) Time-clock systems which aggregate data and restrict transmission to intervals (i.e. every 1 hour, telnet session updates the punches)
c.) Network printers that primarily listen and do not speak.
d.) & more!

When communication upstream is kept to a minimum by the client, the access point may think the client has left and will age out the MAC per normal operation. This prevents the MAC table from growing too large, but can also cause a side effect of quiet network clients being removed from the MAC table while still connected.

A user might experience that certain nodes become "unreachable" over the mesh link over time and must be pinged by a local network device in order for the client to generate traffic targeted upstream.

There are two configuration options that should be noticed when configuring a topology similar to the above design.
a.) Idle Timeout
b.) Static MAC Entries

Both of these configuration options can be found on the settings specific to the mesh point AP.
1.) Select the AP in the Monitor tab and click "Modify"
2.) Expand "Interface and Network Settings"
3.) Ensure the desired ethernet port for bridging is set to "Bridge-Access" or "Bridge-802.1Q" depending on whether the port will be treated as an access port or trunk port respectively.
4.) Expand "Advanced Bridge Configuration"

Idle timeout-
Use the default timeout setting (180 seconds) to clear inactive, dynamically learned MAC addresses from the MAC learning table automatically, or change the timeout to a new value between 10 and 3600 seconds (1 hour).

If the client does not communicate up stream very frequently, it is advised to increase this idle timeout to allow the MAC to be retained in the table on the mesh AP, preventing any loss in traffic forwarding capability

Static MAC Entries
Move statically defined MAC address entries to which the AP can forward traffic through its Ethernet interface from the Available MAC Address column to the Selected MAC Address column. If you do not see a MAC address that you want to use, click the New icon, and define it.

If an administrator wants to be absolutely certain a MAC will be retained in the table on a mesh AP regardless of how frequently it communicates, static MAC entries can be added to the AP that will be retained permanently. Since these are part of the running config of an AP rather than dynamically learned, they will be persistent through a reboot.

Using either one or both of these available configuration options, an administrator can be sure that low traffic clients can maintain a reliable communication channel over a mesh link when connected behind a bridge-access port.
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Tim Ruda, Official Rep

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Posted 4 years ago

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Photo of Andrew MacTaggart

Andrew MacTaggart, Champ

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Hi Tim

This is more of a statement then a question.

Appreciate the effort and great info.

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Tim Ruda, Official Rep

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Hi Andrew,

I jumped the gun and posted this in advance to being prepared to move it to FAQ. I am hoping the admins will take care of that :)
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Done :)