here's the scenario ... downsized an office using a 3825 router with an ATM DS3 Network Module and replaced that with a 2811 using a different ATM DS3 module. Putting the original router back is not an option.
Problem is that the ATM interface loses "line protocol" far too often - there is no pattern but seems to be related to traffic volume. i.e this is a 10M MPLS service and when traffic starts getting above 1M is when the line protocol starts dropping. It'll run perfectly clean for extended periods with minimal traffic but once we introduce a higher volume, we start getting packet drops and the ATM interface line protocol starts dropping.
ATM DS3 Port adapter, 1 port
Example from log:
Jun 18 08:33:29.960: %LINK-3-UPDOWN: Interface ATM1/0, changed state to up
Jun 18 08:33:30.960: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM1/0, changed state to up
Jun 18 08:33:33.256: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 69.183.x.173 (ATM1/0.1) is up: new adjacency
Jun 18 08:35:22.960: %LINK-3-UPDOWN: Interface ATM1/0, changed state to down
Jun 18 08:35:22.992: %DUAL-5-NBRCHANGE: IP-EIGRP(0) 1: Neighbor 69.183.x.173 (ATM1/0.1) is down: interface down
Jun 18 08:35:23.960: %LINEPROTO-5-UPDOWN: Line protocol on Interface ATM1/0, changed state to down
Display of "s int atm1/0"
ATM1/0 is up, line protocol is up
Hardware is RS8234 ATM DS3
MTU 4470 bytes, sub MTU 4470, BW 45000 Kbit/sec, DLY 190 usec,
reliability 255/255, txload 1/255, rxload 5/255
Encapsulation ATM, loopback not set
1023 maximum active VCs, 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 never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 14
Queueing strategy: Per VC Queueing
5 minute input rate 946000 bits/sec, 96 packets/sec
5 minute output rate 38000 bits/sec, 63 packets/sec
2144548 packets input, 1163597874 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 2 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
2165984 packets output, 1215084533 bytes, 0 underruns
0 output errors, 0 collisions, 2 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
Note the output drops but lack of log entries or errors indicating a problem with the ATM module. The 2 CRC errors are due to the interface resets.
My question is if anyone may have any idea what may be happening here to cause a perfectly good MPLS service to start "acting" up simply due to a hardware change. According to the Cisco site, the ATM module is compatible with the 2811 using the IOS code I have installed. I would expect to see output errors or log entries if the ATM module is defective. And don't see how the ATM module itself would cause the line protocol to drop.
The telco is engaged to do end-end testing to try and determine if it is our "new" equipment or something else causing the problem. They have also confirmed that the ATM configuration/parameters are correct and match what they expect.
Any ideas we can try would be appreciated.