07-31-2007 12:36 AM - edited 03-03-2019 06:06 PM
Hi,
I have a weird issue . . . On a router connected to a passport via an ATM card, I was seeing the link flapping, and I was able to see these flaps occuring while in the router and in the logs. After checking the interface, I was seeing increasing output drops even though the link was not over utilized nor was there any QoS setup causing the drops. To be on the safe side, The card has been replaced on the router. I am no longer seeing the link flapping on the router (using term mon or in the log) yet the output drops are still increasing, and our monitoring tool is still reporting link flaps. At this point I am trying to find out what could be causing these Output drops when there is no QoS setup and I am no seeing the "no Buffer" counter incrementing:
lalaland#sho 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, DLY 190 usec,
reliability 255/255, txload 1/255, rxload 1/255<<<<<<<<<<<<<<<<<<<<<<<Low load
Encapsulation ATM, loopback not set
Encapsulation(s): AAL5
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 05:01:04
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 237<<<<<<<<<<<<<<<Increasing
Queueing strategy: Per VC Queueing
5 minute input rate 136000 bits/sec, 80 packets/sec
5 minute output rate 95000 bits/sec, 80 packets/sec
1310894 packets input, 374723235 bytes, 0 no buffer<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<Not incrementing
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 5 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
1190427 packets output, 221624609 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
###############
lalaland#sho int atm1/0.213
ATM1/0.213 is up, line protocol is up
Hardware is RS8234 ATM DS3
Description: ----- Area 31 Default PVC to blablabla -----
Internet address is 172.16.2.62/30
MTU 4470 bytes, BW 6000 Kbit, DLY 190 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ATM
1312105 packets input, 374883790 bytes
1191509 packets output, 221776787 bytes
0 OAM cells input, 0 OAM cells output
AAL5 CRC errors : 5
AAL5 SAR Timeouts : 0
AAL5 Oversized SDUs : 0
AAL5 length violation : 5
AAL5 CPI Error : 0
Last clearing of "show interface" counters never
lalaland#
Any hints or suggestions is welcomed . . .
Thanks
07-31-2007 12:51 AM
Hi,
Is your PVC SBR 6 mbps ? You have not included "show atm pvc" for it.
Anyway, it could be traffic spikes causing the drops. Note the drops are a very small number compared to total sent.
You will not see any buffer failure for a drop cause by filling the output queue.
Hope this helps, please rate post if it does!
07-31-2007 01:02 AM
Thanks for your prompt reply . . . here is the output:
lalaland#sho atm vc
VCD / Peak Avg/Min Burst
Interface Name VPI VCI Type Encaps SC Kbps Kbps Cells Sts
1/0.213 213 13 213 PVC SNAP UBR 40000 UP
lalaland#
07-31-2007 05:05 AM
Do show atm pvc 13/213 and let's see if the drops happened on that particular PVC.
Alos you should include the full service policy applied on that PVC.
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