kern/95665: [if_tun] "ping: sendto: No buffer space available" with TUN interface (easily reproducable with test program)

[Astrodog]

The following reply was made to PR kern/95665; it has been noted by GNATS.

From: Astrodog <astrodog at gmail.com>
To: bug-followup at FreeBSD.org, johan at nocrew.org
Cc:  
Subject: Re: kern/95665: [if_tun] "ping: sendto: No buffer space available" with TUN interface (easily reproducable with test program)
Date: Sun, 8 Oct 2006 00:22:20 -0500

 I can reproduce this problem with some ease.
 
 It occurs when the buffer for tun0 fills up, because the NIC is unable
 to send the packets as quickly as the program is generating them.
 
 This is fairly common on slow or dodgy NICs, when combined with tun/gif/etc.
 
 There is not a real fix, because the outgoing NIC used by tun can
 change, so any attempt to make it aware of the buffer, and throttle
 accordingly would be painfully hacked together.
 
 To confirm that this is actually the issue, increase the size of the
 buffer. You should see a larger number of packets make it through.