"dhclient: send_packet: No buffer space available"

[Walter Parker]

On Tue, Dec 3, 2019 at 8:39 PM Yoshihiro Ota <ota at j.email.ne.jp> wrote:
>
> Hi,
>
> I recently switched internet service provider and got much faster connection.
> However, I started seeing some unstable connections between the WiFi router and FreeBSD.
> I was on FreeBSD 12.0-RELEASE and switched to 12.1-RELEASE.
> Both versions have same symptoms.
>
> I get "dhclient: send_packet: No buffer space available" to console and then I frequently lose connection after seeing it.
> After taking the wlan down and re-connect it with wpa_supplicant, I usually get a connection back.
>
> On the side note, I also see these outputs to console and syslog:
> ath0: bb hang detected (0x4), resetting
> ath0: ath_legacy_rx_tasklet: sc_inreset_cnt > 0; skipping
>
> Does anyone have any advice how to fix/work-around or where to start looking: ath driver, dhclinet, kernel, wlan, and/or wpa_supplicant?
>
> Thanks,
> Hiro
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IIRC, that means that you are running out of mbufs. There are two ways
to fix it, increase the number of mbufs (kern.ipc.nmbufs or
kern.ipc.nmbclusters), or increase the aggressiveness of closing old
network connections (I do this from a menu in pfSense, so I don't
remember the command line setting name off hand).

Searching for the error online suggests that this error can also be
caused if the layer 2 network connection failed, such as a wlan
association failure. Or that there is a network filter somewhere that
is sinking/blocking packets and that this is causing the mbuf queue to
fill up (every network request requires an mbuf). In the past, people
have also fixed this by swapping the network hardware.


Walter

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