In this scenario we are asked to validate a flapping interface.
1] Find the serial interface and verify that it is up/up
attga43c3#sho ip int br | include 10.112.210.45
Serial9/1/1/20:0 10.112.210.45 YES manual up
2] Display the interface and note the errors
attga43c3#sho int s9/1/1/20:0
Serial9/1/1/20:0 is up, line protocol is up
Hardware is cyBus 2CT3+
Description: MNX | MYHOME SERVICES | MYHOUSE | GA | DHEC.123456..ATI | 23853 | 1305937 | 1364629 | USA | MIS |
Internet address is 10.112.210.45/30
MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec, rely 255/255, load 1/255
Encapsulation PPP, crc 16, loopback not set
Keepalive set (10 sec)
LCP Open
Listen: CDPCP
Open: IPCP
Last input 00:00:05, output 00:00:05, output hang never
Last clearing of “show interface” counters never
Input queue: 0/1000/0/0 (size/max/drops/flushes); Total output drops: 5
Queueing strategy: VIP-based fair queuing
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
6534487 packets input, 3035189030 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 1 giants, 0 throttles
116987 input errors, 7228 CRC, 51274 frame, 0 overrun, 0 ignored, 58484 abort
5877595 packets output, 2144676741 bytes, 0 underruns
0 output errors, 0 collisions, 170 interface resets
0 output buffer failures, 0 output buffers swapped out
166 carrier transitions no alarm present
Timeslot(s) Used: 1-24, Transmitter delay is 0 flags, transmit queue length 5
non-inverted data
3] Find the VRF and ping the VRF interface.
attga43c3#sho ip vrf interface | include 10.112.210.45
Serial9/1/1/20:0 12.112.210.45 1612 <— VRF
4] Run an extended Ping to the VRF
Router3#ping vrf 1612
Protocol [ip]:
Target IP address: 10.112.210.46
Repeat count [5]: 5000
Datagram size [100]: 1500
Timeout in seconds [2]: 1
Extended commands [n]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5000, 1500-byte ICMP Echos to 10.112.210.46, timeout is 1 seconds:
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
In the above ping I wanted to really hammer the heck out of circuit. In this example we see that the circuit is clocking massive input errors and no output. Instead of me writing what I did to correct this, I’m going to leave this post open for the reader to comment what they think I did. Note the bold errors and circuit type.
This post was written by...
Ron Staples – who has written 36 posts on ConfigBytes.
Ron has been working in the data, voice technologies field for over 20 years, he obtain his CCNA in 1999 and has worked for several fortune 500 companies. Since then he has re certified his CCNA and earned the following additional certifications, CCNA Voice and CCRMS.
