[Cerowrt-devel] what stats do people want from conference wifi?
david at lang.hm
Sat Feb 7 21:02:55 EST 2015
In the next few days I'm going to be building the openwrt images to use at the
SCaLE conference. I will have ~50 APs deployed supporting ~3k attendees. This
will be running on WNDR3700v2 and WNDR3800 APs. Since I am compiling the
firmware myself, I can add in patches to gather and log stats for things that
are not normally reported
The wireless network architecture is:
separate ESSIDs for 2.4 vs 5.
each band gets bridged to a different VLAN
the APs are configured not to forward broadcast traffic from one wireless client
to another on the same AP (although broadcast traffic from one AP probably goes
out others after hitting the wire now that I think about it)
I have all logs from the APs sent to a central logserver
I have use rrdtool to catpture normal bandwith/cpu/etc stats
I also have rrdtool capture how many clients are connected to each ESSID every
What else can I gather related to the wifi?
I think it would be useful if we could gather info along the lines of
amount of airtime used
how much latency is added to packets while waiting to transmit because it's hearing something else transmit?
amount of unused airtime available
average effective bit rate
percentage of time spent doing broadcasts (things required to operate at the
lowest bit rate)
Part of the reason that I compile my own firmware images is that I completely
disable connection tracking in the kernel (because clients may move from one AP
to another in the middle of a connection it's a waste of cpu and memory to
track), and as a result of these optimizations, there is actually quite a bit of
CPU available. The boxes almost never hit 20% cpu utilization, so there's quite
a bit available to gather other stats.
some of the stats I gather are in messages spit out by the kernel, others from
scrips running on the box querying things in /proc or /sys, and others from
watching logs and summarizing them once a minute. I even have a process that
goes threough all the connection logs for the duration of the show and graph
how many unique MAC addresses we've seen and a breakdown into the different
vendor prefixes. If there's a way to get the data, I can support it.
If there are fq_codel stats that people would find interesting in this
environment, I can gather those as well (both on the APs and on the Debian based
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