kern/86261: 'out of buffer space' after many PPPoE re-dial attempts, connectivity lost

[Bob Frazier]

>Number:         86261
>Category:       kern
>Synopsis:       'out of buffer space' after many PPPoE re-dial attempts, connectivity lost
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Sat Sep 17 17:00:24 GMT 2005
>Closed-Date:
>Last-Modified:
>Originator:     Bob Frazier
>Release:        5.4-STABLE (7/21/2005)
>Organization:
SFT INc.
>Environment:
FreeBSD BSDServer.SFT.local 5.4-STABLE FreeBSD 5.4-STABLE #0: Sat Jul 23 04:33:01 PDT 2005 root at BSDServer.SFT.local:/usr/obj/usr/src/sys/MY_KERNEL  i386

>Description:
      At various times my DSL service provider loses connectivity, and ppp must re-dial the PPPoE connection to maintain it.  After the system has been running for quite some time.  uptime would have likely been since the last kernel build (around 7/22/2005).  Since that time period, countless re-dials by ppp have been performed.

At approximately midnight, I had a series of redials take place, which ultimately resulted in the following errors in /var/log/messages, and a complete loss of internet connectivity.

Sep 16 23:59:13 BSDServer routed[289]: ignore RTM_CHANGE without mask
Sep 16 23:59:13 BSDServer routed[289]: ignore RTM_CHANGE without mask
(these two errors happen all of the time whenever the ppp connection is established)
Sep 16 23:59:25 BSDServer ppp[230]: tun0: Warning: deflink: Reducing configured MRU from 1500 to 1492
(this is also normal)
Sep 17 00:01:00 BSDServer routed[289]: Send sendto(tun0, 216.175.112.1.520): No buffer space available
Sep 17 00:01:30 BSDServer routed[289]: Send sendto(tun0, 216.175.112.1.520): No buffer space available
Sep 17 00:03:30 BSDServer last message repeated 4 times

The previous sequence then repeated itself every few minutes as ppp attempted to re-dial the PPPoE connection indefinitely.  I am using a Zyxel DSL modem through earthlink.

>How-To-Repeat:
I have only seen this problem once before, and it was caused by the same thing - ISP drops connection a sufficient number of times until ppp has re-dialed enough to cause the 'no buffer space available' error.  An extremely unreliable DSL connection (constantly dropping) with a lot of internet traffic and connections to services like IRC that stay up for days at a time over this connection, gigabytes of data transferred, services like http and ftp and ssh providing content, etc. connected to the internet for several weeks using PPPoE over a DSL connection where 'ppp' is providing the PPPoE login.  At some point a resource limit is exceeded, and then all internet connectivity is lost.
>Fix:
      rebooting the system restored connectivity in both cases.  This problem never occurred prior to FreeBSD 5.3-RELEASE, possibly not even until FreeBSD 5.4-RELEASE.

>Release-Note:
>Audit-Trail:
>Unformatted: