[c-nsp] c836 router rfc1483-bridged with NAT / problem every five minutes

[Elmar Pigeaud]

We have a Cisco 836 ADSL over ISDN router, configured for RFC1483
bridging, with NAT. It seems to be working fine, however, every five
minutes (exact) it brings down the ATM0 interface, which brings down
the bridge (BVI1). After about 20 seconds it comes up again, and
connection comes back up, no errors logged other than that the
connection was brought down.

I saw a lot (392) of interface resets for ATM0,
none for the other (BVI1, ETH0) interfaces. 199 Packet drops...

Has anyone encountered a similiar problem? Any hints for
more troubleshooting?

Following are running config, version and log post.

Thanks,

Pjn

VERSION:
Cisco IOS Software, C836 Software (C836-K9O3Y6-M), Version 12.3(8)T11,
RELEASE SOFTWARE (fc1)
ROM: System Bootstrap, Version 12.2(11r)YV3, RELEASE SOFTWARE (fc2)

System image file is "flash:c836-k9o3y6-mz.123-8.T11.bin"

CONFIG:
Current configuration : 1870 bytes
!
version 12.3
no service pad
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname c836
!
boot-start-marker
boot-end-marker
!
logging buffered 10000 debugging
no logging console
!
no aaa new-model
ip subnet-zero
!
!
ip ips po max-events 100
no ftp-server write-enable
!
!
username admin privilege 15 secret 5 <pw>
!
!
!
bridge irb
!
!
interface Ethernet0
 description $ETH-LAN$$ETH-SW-LAUNCH$$INTF-INFO-Ethernet 10/100$
 ip address 192.168.20.1 255.255.255.0
 ip nat inside
 ip virtual-reassembly
 hold-queue 100 out
!
interface BRI0
 no ip address
 shutdown
!
interface ATM0
 no ip address
 no ip mroute-cache
 atm vc-per-vp 64
 no atm ilmi-keepalive
 dsl operating-mode auto
 bridge-group 1
 pvc 0/34
  encapsulation aal5snap
 !
!
interface FastEthernet1
 no ip address
 duplex auto
 speed auto
!
interface FastEthernet2
 no ip address
 duplex auto
 speed auto
!
interface FastEthernet3
 no ip address
 duplex auto
 speed auto
!
interface FastEthernet4
 no ip address
 duplex auto
 speed auto
!
interface BVI1
 ip address dhcp
 ip nat outside
 ip virtual-reassembly
!
ip classless
ip route 0.0.0.0 0.0.0.0 BVI1
ip http server
ip http authentication local
ip http secure-server
ip http timeout-policy idle 5 life 86400 requests 10000
ip nat inside source list 1 interface BVI1 overload
!
!
access-list 1 permit 192.0.0.0 0.255.255.255
!
control-plane
!
bridge 1 protocol ieee
bridge 1 route ip
!
line con 0
 login local
 no modem enable
line aux 0
line vty 0 4
 privilege level 15
 login local
 transport input telnet ssh
!
scheduler max-task-time 5000
!
sntp server 193.67.79.202
end

LOG:

Jun 28 09:19:52.477: %LINK-3-UPDOWN: Interface ATM0, changed state to
down
Jun 28 09:19:53.477: %LINEPROTO-5-UPDOWN: Line protocol on Interface
ATM0, changed state to down
Jun 28 09:19:54.477: %LINK-3-UPDOWN: Interface BVI1, changed state to
down
Jun 28 09:19:55.477: %LINEPROTO-5-UPDOWN: Line protocol on Interface
BVI1, changed state to down
Jun 28 09:20:09.929: %LINK-3-UPDOWN: Interface ATM0, changed state to
up
Jun 28 09:20:10.929: %LINEPROTO-5-UPDOWN: Line protocol on Interface
ATM0, changed state to up
Jun 28 09:20:11.793: %LINK-3-UPDOWN: Interface BVI1, changed state to
up
Jun 28 09:20:12.793: %LINEPROTO-5-UPDOWN: Line protocol on Interface
BVI1, changed state to up
Jun 28 09:24:52.513: %LINK-3-UPDOWN: Interface ATM0, changed state to
down
Jun 28 09:24:53.513: %LINEPROTO-5-UPDOWN: Line protocol on Interface
ATM0, changed state to down
Jun 28 09:24:54.513: %LINK-3-UPDOWN: Interface BVI1, changed state to
down
Jun 28 09:24:55.513: %LINEPROTO-5-UPDOWN: Line protocol on Interface
BVI1, changed state to down
Jun 28 09:25:09.973: %LINK-3-UPDOWN: Interface ATM0, changed state to
up
Jun 28 09:25:10.973: %LINEPROTO-5-UPDOWN: Line protocol on Interface
ATM0, changed state to up
Jun 28 09:25:11.785: %LINK-3-UPDOWN: Interface BVI1, changed state to
up
Jun 28 09:25:12.785: %LINEPROTO-5-UPDOWN: Line protocol on Interface
BVI1, changed state to up