This is an ADSL atm network using a 2811 router.
My atm port is 10.15.254.2, edge router is 10.15.254.1
1. Every once a while the B* 0.0.0.0/0 [20/0] via 10.15.254.1, 6d20h default route would go disappeared, so BGP would change to Active.
2. show inteface bri said, atm 0/0 was up/up
3. I connected to the router through the back door, found out, the atm 0/0 port is not pingable.
4. To resolve the issue, I would need a shut/no shut on the atm 0/0, BGP would be reestablish, and it would work for 5-15 days.
Here is my normal routing table
C 10.56.0.0/13 is directly connected, FastEthernet0/0
C 10.15.254.10/32 is directly connected, Loopback0
C 10.15.254.0/30 is directly connected, ATM0/0/0
B 10.15.254.0/24 [200/0] via 0.0.0.0, 6d20h, Null0
C 10.15.254.128/25 is directly connected, GigabitEthernet1/0
B* 0.0.0.0/0 [20/0] via 10.15.254.1, 6d20h
=====show log when default route disappear==
Oct 6 11:01:36.330 CDT: %PIM-5-DRCHG: DR change from neighbor 0.0.0.0 to 10.152
.254.2 on interface ATM0/0/0
Oct 6 11:01:45.219 CDT: %LINK-3-UPDOWN: Interface ATM0/0/0, changed state to do
wn
Oct 6 11:01:46.219 CDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM0/0/
0, changed state to down
Oct 6 11:02:05.223 CDT: %LINK-3-UPDOWN: Interface ATM0/0/0, changed state to up
Oct 6 11:02:06.223 CDT: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM0/0/
0, changed state to up
Oct 6 11:02:06.351 CDT: %PIM-5-DRCHG: DR change from neighbor 0.0.0.0 to 10.15
.254.2 on interface ATM0/0/0
Oct 6 11:02:07.919 CDT: %PIM-5-NBRCHG: neighbor 10.152.254.1 UP on interface AT
M0/0/0
Oct 6 11:03:52.922 CDT: %PIM-5-NBRCHG: neighbor 10.15.254.1 DOWN on interface
ATM0/0/0 non DR
===============
ATM0/0/0 is up, line protocol is up
Hardware is HWIC-DSLSAR (with Alcatel ADSL Module)
Internet address is 10.15.254.2/30
MTU 4470 bytes, sub MTU 4470, BW 512 Kbit, DLY 1000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ATM, loopback not set
Encapsulation(s): AAL5 AAL2, PVC mode
23 maximum active VCs, 256 VCs per VP, 1 current VCCs
VC Auto Creation Disabled.
VC idle disconnect time: 300 seconds
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 6d07h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Per VC Queueing
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 0 bits/sec, 0 packets/sec
984032 packets input, 500586163 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
838225 packets output, 106313349 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
===============
There are several hundred routers having the same problem lately which connected different ISP.
I think there are 3 ways to drop default route route
A. My NIC has problem.
B. The DSLAM has problem on 10.15.254.1
C. IOS has changed about 8 weeks ago. I am using Version 12.4(13r)T
D. I am planning to add a static route with AD = 21, hopefully, the static would connect to ISP, when default is gone.
Anyother suggestion?
