GRE tunnel problem om FreeBSD 5.2.1

[Erik Mossberg]

Hello,
   I have a weird problem with a GRE tunnel, the setup is as follows;
   gre0: flags=b051<UP,POINTOPOINT,RUNNING,LINK0,LINK1,MULTICAST>
mtu
   1476
           tunnel inet 213.67.20.137 --> 194.145.248.113
           inet 194.145.248.138 --> 194.145.248.137 netmask 0xfffffffc
   And I've tried both w/ and w/o the link1 option mentioned in the man
   page for gre.

netstat -rn -f inet:
   Destination        Gateway            Flags    Refs      Use  Netif
   Expire
   default            213.67.20.1        UGS        17 19250541    rl1
   127.0.0.1          127.0.0.1          UH          1     1802    lo0
   192.168.0          link#1             UC          0        0    rl0
   192.168.0.54       00:04:75:c8:18:d8  UHLW        2  5683090    rl0
   608
   192.168.0.55       link#1             UHLW        2      140    rl0
   192.168.0.91       00:0d:54:9a:d2:d1  UHLW        0    13538    rl0
   1039
   192.168.0.95       00:0d:88:81:fd:98  UHLW        0   766395
   rl0      5
   192.168.5.2        192.168.5.1        UH          0       12   gif2
   194.145.248.137    194.145.248.138    UH          0     1177   gre0
   213.67.20          link#2             UC          0        0    rl1
   213.67.20.1        00:10:67:00:c4:39  UHLW        1        0    rl1
   234
   213.67.20.108      00:10:67:00:c4:39  UHLW        0       12    rl1
   822
   213.67.20.137      127.0.0.1          UGHS        0      136    lo0

   when I try to ping 194.195.248.137 I have a 95% packet loss, but when
   pinging from remote to 194.145.248.138 works just fine with no packet
   loss.

   tcpdump -eni rl1 shows this:
   22:05:55.148354 0:10:a7:13:bf:58 0:10:67:0:c4:39 0800 122:
   213.67.20.137 > 194.145.248.113: gre (frag 49403:88 at 752+)
   22:05:56.158351 0:10:a7:13:bf:58 0:10:67:0:c4:39 0800 122:
   213.67.20.137 > 194.145.248.113: gre (frag 49410:88 at 51176)

   Sometimes the packet 1 or 2 packets goes through and gets a reply
   though.

   I use:
   FreeBSD 5.2.1-RELEASE-p5 #3: Sun Apr 18 22:25:17 CEST 2004
   omicron at fisken:/usr/obj/usr/src/sys/merltock  i386

   When google-ing for this problem I found this:
   http://lists.freebsd.org/pipermail/freebsd-current/2004-February/02039
   4.html

   Which seems to be the same problem, can the bug have been brought back
   afterwards?
   I hope I didn't miss any info..

I will try upgrading to 5.3-RC1, seems to have been alot of fixes
since then, but I'd be glad for any information what might be the
cause of this problem.

Thanks.

   Regards,
   Erik