tinc - Jun 2014 - where are going my packets?

Hello,

I have multiple nodes interconnected with each other with tinc1.0.19 (debian
stable) in routed mode.

Some connections between nodes are backup links and have a high latency or not
much bandwidth.

I would like to setup a "logic balanced" routing, so my traffic should
"go" with preference to links that are better than others.

I saw that I can use the Weight on the Subnet but I didn't found any way to
work with that (or troubleshoot it)

Should be also interesting to know the routing path of my packets to
troubleshoot the routing.

Q1) how I can force Subnet to be reachead via a preferred path?

Q2) what is the logic choosed by tinc for routing between nodes? I read that is
aphabetical by node name but I saw that is not actually true

Q3) how I can do a traceroute-like command to see the passed through nodes? I
tried the USR2 signal but the output is not useful, subnets section say only the
owner of it and not the path. I read in the mailing list someone said that is
equal to the routing table, but not exacly, the routing table say also the next
hop, in the tinc output there is only the "target" and not the next
hop node.

Thanks

Matteo

On Tue, Jun 24, 2014 at 03:28:27PM +0200, Matteo Sgalaberni wrote:
> I saw that I can use the Weight on the Subnet but I didn't found any
way to work with that (or troubleshoot it)
The Weight on Subnets only influences which destination node is chosen
when multiple nodes have the same Subnet. It does not affect how tinc
routes those packets via intermediate nodes.
> Should be also interesting to know the routing path of my packets to
troubleshoot the routing.
> 
> Q1) how I can force Subnet to be reachead via a preferred path?
With tinc 1.0.x, you can't really influence which path is taken.
> Q2) what is the logic choosed by tinc for routing between nodes? I read
that is aphabetical by node name but I saw that is not actually true
First of all, tinc will normally try to make a direct connection to the
destination node. If that doesn't work, it will route packets via
intermediate nodes that can be reached via the meta connections (those
that you specify with ConnectTo). It will always choose a path with the
least number of hops along those meta connections. If there are multiple
paths with the same number of hops, then for each hop where it has a
choice, it will indeed choose the node with the lowest alphabetical
name.
> Q3) how I can do a traceroute-like command to see the passed through nodes?
I tried the USR2 signal but the output is not useful, subnets section say only
the owner of it and not the path. I read in the mailing list someone said that
is equal to the routing table, but not exacly, the routing table say also the
next hop, in the tinc output there is only the "target" and not the
next hop node.
The list of Subnets is only used to determine the final destination
node. If you know the destination node, you can look that one up in the
node list (also in the USR2 output). There are two values there,
"nexthop" and "via". It will try to send the packets
directly to the
"via" node, if that doesn't work it will fall back to the
"nexthop"
node.

-- 
Met vriendelijke groet / with kind regards,
     Guus Sliepen <guus at tinc-vpn.org>
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