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How to force a route

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w8erd
How to force a route
Is there a simple way to force a route between nodes?  We have a situation where two nodes are far apart, and the routing algorithm chooses to go
directly between them,  and we get pings of 2-3 seconds.
Yet there is an intermediate node that has pings of 15 ms to either end node.  We need to force the route to use the intermediate node.

Thanks!

Bob W8ERD

 
KG6JEI
routes are calculated by
routes are calculated by packet losss where it's calculated that one route will have greatest chance of delivering the data (speed/latency isn't a considered factor.) It certainly is not 100% foolproof but it's intended to give the best chance for the information to make tnacross the network.

You could possibly tweak this by aiming your antennas off axis from each other towards the middle node but currently there is no user configurable way to change the path selection.

 
w8erd
Forcing routes
This unfortunate.   Our antennas are omnis high up on towers, so we cannot change anything there. 
So we have the situation where it is almost impossible for 2 nodes to communicate, because the routing algorithm chooses to use the minimum number of hops.

We have another similar situation where two nodes are separated by a hill that blocks most of the signal, so the signal is weak and we cannot send video, which is exactly what we need to do.  So we will try a node off to the side which will have direct line of sight between the two nodes, to act as a relay node.
But we are concerned that the weak signal coming over the hill will still be chosen as the used path, making our relay node useless. We will try directional antennas in this case, but are still worried that it will not work.  This is a high-profile public annual event that will gain us great PR and cooperation from various agencies to help us expand the mesh network elsewhere. if we can make it work.

Bob  W8ERD
K5DLQ
K5DLQ's picture
this is a limitation of the

this may be a limitation of the routing protocol (OLSR v1).
There is an open ticket (http://bloodhound.aredn.org/ticket/135), but the outcome may require an AREDN protocol version jump. (ie.  V3 to V4)

KG6JEI
"So we have the situation
"So we have the situation where it is almost impossible for 2 nodes to communicate, because the routing algorithm chooses to use the minimum number of hops."
The system doesn't choose minimum number of hops,  It chooses minimal RF Transmissions.   This is done including the probability of packet loss on each hop route to keep the risk of interference down.   As I noted below I would strongly suggest checking the distance parameter is configured correctly as the symptoms to me sound  a bit like the distance parameter isn't set correctly, but this is hard to know for sure without a support data file being attached to the forum post to see just what the network you have looks like.

You mention these sites are using Omni's. Not knowing what exactly your deployment is like I will say I generally don't recommend two sites talk to each other with Omni's  Omni's can be used to let users access a mesh node, but really the only time you want a signal to come in an Omni and then go out an Omni is when they are in the same "cell." Going between two major sites you really want this to be more of a redundant backbone design to get quality links. Network design may indeed be one item for you to look at to improve the network quality.


I will note that if none of the answers here do work you can always consider submitting a feature request ( http://bloodhound.aredn.org/ ) to get it considered in the official queue.
WB9KMO
Distance?
How about shortening your Distance setting so the distant sights can't communicate directly. Rod Fritz, WB9KMO  rod@sbatv.org
KG6JEI
I do recommend checking the
I do recommend checking the distance on the two nodes.

The distance should be greater than the physical distance between the two of them.

Having the distance shorter than the two nodes are apart will not stop them from communicating witch each other but it will cause an "RF Packet Storm" (frequency jam) that can seriously hinder packet transmissions.
KE2N
KE2N's picture
forcing a route

If your half-way station could be configured as two radios back-to-back (DtD) then you could use a different SSID on each of the hops. With that arrangement, the two far nodes will not attempt to talk to each other, so OLSR will not be a problem.  

If this does not screw up the rest of your network, it should do what you want. 

GL

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