Interface does not show any traffic.....

Unanswered Question
Feb 25th, 2009


One of the interface Gig1/0/1, which is layer-3, is not showing any traffic although this is connected to ATT router which must have some traffic passing by.

Here is the output 'sho int gig1/0/1':

RPC6641-6-3748G-1#sho int gig1/0/1

GigabitEthernet1/0/1 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 001e.bde3.55cc (bia 001e.bde3.55cc)

Description: ***Uplink to AT&T MPLS Router***

Internet address is

MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,

reliability 255/255, txload 1/255, rxload 0/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX

input flow-control is off, output flow-control is unsupported

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:01, output 00:00:00, output hang never

Last clearing of "show interface" counters 01:52:09

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

4844635 packets input, 4407245438 bytes, 0 no buffer

Received 1463 broadcasts (1452 IP multicasts)

0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored

0 watchdog, 1463 multicast, 0 pause input

0 input packets with dribble condition detected

4930753 packets output, 1151893078 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier, 0 PAUSE output

0 output buffer failures, 0 output buffers swapped out


Thansk and regards,


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Istvan_Rabai Wed, 02/25/2009 - 09:14

Hi Gaurav,

Look at these lines:

4844635 packets input, 4407245438 bytes, 0 no buffer

4930753 packets output, 1151893078 bytes, 0 underruns

They show there was traffic on the interface.

Then look at these lines:

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

They show there was no significant traffic on the interface in the last 5 minutes.

These lines show the average traffic rate calculated for a 5 minutes interval.

You can change the calculation interval with the "load-interval" command under interface config mode.

"load-interval 30" changes the calculation interval to 30 seconds and the output of these lines will change faster.


Istvan Wed, 02/25/2009 - 09:25

Thanks Istvan,

.... you are right, but it should show some traffic whatever less it may be, other interface is showing 2000bps, if it can show this small traffic why is it not showing the traffic on WAN interface which is ofcourse one of the heavily utilised interfaces. I want to know the traffic which is going out and getting in through this interface. Kindly help.

Thanks and regards,


Istvan_Rabai Wed, 02/25/2009 - 10:18

Hi Gaurav,

I don't know your configuration, but my supposition is that on this interface there is some routing potocol keepalive only.

This keepalive traffic is so small that it doesn't even show up in the interface stats.

Check if the above numbers that I pointed out to you are changing with the time. If the number of incoming and outgoing packets increases then there is traffic.

You should send some user traffic across the interface for some significant traffic to show up in the stats.

Check your routing tables if the traffic is routed across this interface.

Use the debug and traceroute commands to test and monitor your config, so you can be sure the traffic is going through that interface and not through any other.




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