getting error on cisco 2921 | %IP-3-LOOPPAK: Looping packet detected and dropped

[Ramesh Babu]

Hi Team,

We are getting following error on cisco 2921, ios : c2900-universalk9-mz.SPA.150-1.M2.bin,

Interface Serial0/0/0:0 is running BGP, please do the needful, because of this error we are getting CRC error, input error, runts.,

%IP-3-LOOPPAK: Looping packet detected and dropped -
src=172.17.1.254, dst=172.2.203.110, hl=20, tl=56, prot=1, sport=0, dport=0
in=Serial0/0/0:0, nexthop=172.2.21.37, out=Serial0/0/0:0
options=none -Process= "IP Input", ipl= 0, pid= 113,

Please do the needful. How to solve this issues.

Thanks & Regards,

Ramesh Babu.A.

[Leo Laohoo]

Kindly post the complete output to the command "sh interface Serial0/0/0".

[Ramesh Babu]

Hi Leo,

Thanks for your reply,

A#sh int Se0/0/0:0
Serial0/0/0:0 is up, line protocol is up
Hardware is DSX1
Description: ******
Internet address is 172.2.21.38/30
MTU 1500 bytes, BW 1536 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, LCP Open
Open: IPCP, loopback not set
Keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 00:32:27
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 424
Queueing strategy: Class-based queueing
Output queue: 0/1000/0 (size/max total/drops)
5 minute input rate 4000 bits/sec, 4 packets/sec
5 minute output rate 7000 bits/sec, 4 packets/sec
9933 packets input, 1606646 bytes, 0 no buffer
Received 0 broadcasts, 3 runts, 0 giants, 0 throttles
11 input errors, 11 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
14464 packets output, 3032536 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
Timeslot(s) Used:1-24, SCC: 0, Transmitter delay is 0 flags

For the destination ip address we have nat on this device

A#ip nat outside source static 172.2.203.110 198.199.226.242

Thanks & Regards,

Ramesh Babu.A.

[Leo Laohoo]

I'd be getting the ISP to do a bit hardware-based error rate (BER) test on the line.