Open Mesh: Issueshttps://www.open-mesh.org/https://www.open-mesh.org/favicon.ico?16699090422020-08-21T08:46:18ZOpen Mesh
Redmine batman-adv - Bug #416 (Feedback): B.A.T.M.A.N. V: include packet loss in link throughput estimationhttps://www.open-mesh.org/issues/4162020-08-21T08:46:18ZAntonio Quartulli
<p><strong>Scenario:</strong><br />I have 2 dual radio APs (1 x 2.4GHz and 1 x 5GHz, both ath10k).<br />The APs are placed in two different rooms with various walls in between. Because of that meshing over 5GHz is quite unreliable.</p>
<p><strong>Problem:</strong><br />Batman-adv is often selecting the route going over the 5GHz radio because the tx rate (used to estimate the throughput) is often higher.<br />This route selection, however, turns out to be a very bad choice because the packet loss makes the 5GHz link unusable (I can hardly ping the other AP with batctl p).</p>
<p>(I wonder though, why is the tx rate often this high if packet loss is high as well...?)</p>
<p><strong>Proposal:</strong><br />One way to mitigate this issue would be to include the packet loss in the 1-hop link throughput estimation logic.<br />Mixing throughput and packet loss can be quite complicated, therefore I would like to keep it simple: i.e. when packet loss over a link is below 50%, drop the throughput to 0.1Mbps.<br />This way that link is heavily penalized and excluded from the routing (unless it's the only choice we have).</p>
<p>To measure the 1-hop packet loss we could either use the OGMs (similarly to what we did in B.A.T.M.A.N. IV, but it may become ugly quite fast) or we could rely on counting the received ELPs and sending back a periodic report to the sender.</p>
<p>Opinions? Comments?</p> batman-adv - Bug #187 (Rejected): Asymmetric VLAN generates loop https://www.open-mesh.org/issues/1872014-05-28T05:51:45ZAntonio Quartulli
<p>In case of an asymmetric VLAN configuration as shown in the picture it is possible to generate a loop even if BLA is enabled.</p>
<p><img src="https://www.open-mesh.org/attachments/download/460/bla-loop.png" alt="" loading="lazy" /></p>
The loop is triggered by the fact that the two potential backbone nodes won't recognize each other. This can be understood by looking at the steps taken by a BLA ANNOUNCE message:
<ol>
<li>is generated at node B for VLAN y</li>
<li>is broadcast'd over eth0.x</li>
<li>reaches eth0 on node A and does not get decapsulated</li>
<li>enters bat0.y and gets encapsulated once again</li>
<li>batman-adv does not find the BLA message because the "encapsulated_proto" field is not ARP</li>
<li>the message gets forwarded in the mesh because the node thinks to be alone on the LAN</li>
<li>the message reaches node B the loop starts</li>
</ol>
<p>I don't see a clear solution to this problem because even if we make batman-adv decapsulate any packet until we get to the inner layer, we still have the problem that node A won't be recognized by nodeB (nodeA will always send with no VLAN header).</p>
<p>Any thought?</p> batman-adv - Bug #148 (Closed): interface usage_count = 1 while trying to deactivate the hard int...https://www.open-mesh.org/issues/1482011-05-10T22:23:12ZAntonio Quartulli
<p>When I try to remove the module of my wifi device (it is the primary_if for bat0), modprobe hangs and dmesg shows this message:</p>
<p>unregister_netdevice: waiting for wlan0 to become free. Usage count = 1</p>
<p>Steps to reproduce it:</p>
<p>- insmod batman-adv<br />- insmod device_driver<br />- batctl if add wlan0<br />- ifconfig wlan0 up<br />- ifconfig bat0 up<br />- modprobe -r device_driver</p>
<p>At this point the modprobe hangs. In another terminal I tried to do<br />modprobe -r batman-adv<br />and everything went fine here.</p>