FreeBSD 8.2 and MPD5 stability issues - update

[Adrian Minta]

Hi,
Without FLOWTABLE the system is stable an I was able to increase the
number of l2tp sessions. A major improvement came when I replaced the
network card with a multiqueue model (igb). The limit is now around 6300
active sessions. If I try to go over this limit the mpd5 starts to loose
old sessions and the number quickly decrease.
I believe I encounter an internal mpd5 timing issue. Is anybody aware of
such thing ?

The server is now a dual xeon E5520 and the load is around 6.8 at peak.

The server has igb0 10.42.1.1/16 and 50 aliases.
My mpd.conf looks like this:
startup:
        #configure mpd users
        set user admin pass admin
        set user foo bar
        #configure the console
        set console self 127.0.0.1 5005
        set console open
        #configure the web server
        set web self 10.42.1.1 5006
        set web open

        set global l2tptimeout 60

default:
        load l2tp_server1
        load l2tp_server2
        load l2tp_server3
        load l2tp_server4
        load l2tp_server5
        load l2tp_server6
        load l2tp_server7
        load l2tp_server8
        load l2tp_server9
        load l2tp_server10
        load l2tp_server11
        load l2tp_server12
        load l2tp_server13
        load l2tp_server14
        load l2tp_server15
        load l2tp_server16
        load l2tp_server17
        load l2tp_server18
        load l2tp_server19
        load l2tp_server20
        load l2tp_server21
        load l2tp_server22
        load l2tp_server23
        load l2tp_server24
        load l2tp_server25
        load l2tp_server26
        load l2tp_server27
        load l2tp_server28
        load l2tp_server29
        load l2tp_server30
        load l2tp_server31
        load l2tp_server32
        load l2tp_server33
        load l2tp_server34
        load l2tp_server35
        load l2tp_server36
        load l2tp_server37
        load l2tp_server38
        load l2tp_server39
        load l2tp_server40
        load l2tp_server41
        load l2tp_server42
        load l2tp_server43
        load l2tp_server44
        load l2tp_server45
        load l2tp_server46
        load l2tp_server47
        load l2tp_server48
        load l2tp_server49
        load l2tp_server50

l2tp_server1:
        set ippool add pool1 10.1.2.2 10.1.3.254
        create bundle template B1
        set iface disable proxy-arp
        set iface idle 1800
        set iface enable tcpmssfix
        set ipcp yes vjcomp
        set ipcp ranges 10.1.2.1/23 ippool pool1
        set ipcp dns 10.42.0.1 8.8.4.4
        set bundle enable compression
        set ccp yes mppc
        set mppc yes e40
        set mppc yes e128
        set mppc yes stateless
        create link template L1 l2tp
        set link action bundle B1
        set link enable multilink
        set link yes acfcomp protocomp
        set link no pap chap
        set link enable chap
        set link keep-alive 60 180
        set auth max-logins 10000
        set link mtu 1460
        set l2tp self 10.42.1.1
        set link enable incoming
l2tp_server2:
        set ippool add pool2 10.1.4.2 10.1.5.254
        create bundle template B2
        set iface disable proxy-arp
        set iface idle 1800
        set iface enable tcpmssfix
        set ipcp yes vjcomp
        set ipcp ranges 10.1.4.1/23 ippool pool2
        set ipcp dns 10.42.0.1 8.8.4.4
        set bundle enable compression
        set ccp yes mppc
        set mppc yes e40
        set mppc yes e128
        set mppc yes stateless
        create link template L2 l2tp
        set link action bundle B2
        set link enable multilink
        set link yes acfcomp protocomp
        set link no pap chap
        set link enable chap
        set link keep-alive 60 180
        set auth max-logins 10000
        set link mtu 1460
        set l2tp self 10.42.1.2
        set link enable incoming
.....
l2tp_server50:
        set ippool add pool50 10.1.100.2 10.1.101.254
        create bundle template B50
        set iface disable proxy-arp
        set iface idle 1800
        set iface enable tcpmssfix
        set ipcp yes vjcomp
        set ipcp ranges 10.1.100.1/23 ippool pool50
        set ipcp dns 10.42.0.1 8.8.4.4
        set bundle enable compression
        set ccp yes mppc
        set mppc yes e40
        set mppc yes e128
        set mppc yes stateless
        create link template L50 l2tp
        set link action bundle B50
        set link enable multilink
        set link yes acfcomp protocomp
        set link no pap chap
        set link enable chap
        set link keep-alive 60 180
        set auth max-logins 10000
        set link mtu 1460
        set l2tp self 10.42.1.50
        set link enable incoming