Source from input and output

[kian_hong2000]

I have some questions based on the output showing individual interface port.

Take this interface as an example. Say i have connected a PC to this port.

1) Why does the interface input less than the output?

2) How do you define the input and output based on this connection?

3) I have come across whereby there is no input packets but the output packets keep on increasing. Why does this happen?

4) How come the number of the packets input/output and bytes is different?

FastEthernet0/1 is up, line protocol is up

Hardware is Fast Ethernet, address is 0003.6b14.5860 (bia 0003.6b14.5860)

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

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

Encapsulation ARPA, loopback not set

Keepalive not set

Auto-duplex , Auto Speed , 100BaseTX/FX

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

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

Last clearing of "show interface" counters 2y35w

Queueing strategy: fifo

Output queue 0/40, 0 drops; input queue 0/75, 0 drops

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

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

410389 packets input, 43867181 bytes

Received 26488 broadcasts, 0 runts, 0 giants, 0 throttles

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

0 watchdog, 23157 multicast

0 input packets with dribble condition detected

35573448 packets output, 180077928 bytes, 0 underruns

0 output errors, 0 collisions, 1 interface resets

0 babbles, 0 late collision, 0 deferred

0 lost carrier, 0 no carrier

0 output buffer failures, 0 output buffers swapped out

[royalblues]

Cos the outpackets would also include the packets generated by the router.

Narayan

[bvsnarayana03]

Input on the router interface indicates the traffic originated by PC. Output statistice on interface indicate the traffic back to the pc.

There may be instances when the pc is downloading or copying heavy content from network, but not much traffic sent out. This may be the reason for high output stats as compared to less or no input on interface.

Also, the stats shown on interface is for the 5 minutes duration. You may change it to real-time by "load-interval xyz" command on the interface. where xyz is time in seconds.

[glen.grant]

1. Depends on what the user is doing , if he is writing a bunch of info to a server then obviously his input will be much greater than the output .

2. not sure what you asking here.

3. Output will see all broadcast and or multicast traffic no matter what so those will increase.

4. As said is #1 they will always be different depending on what the user is doing .

[kian_hong2000]

Thanks everyone!

The device is actually a Switch.

For (2): from all the aswers that you all give, can i say that packet input is like (uploading) and packet output is like (download)?

I have another question related to this. I have this interface say interface fa0/1. I cannot see the mac address of the equipment. The port is up.

I can see that the packet output is increasing but the packet input is zero. Could it be the reason for the port to be intermittent?

[bvsnarayana03]

Do u mean to say the arp times out for this port. can u ping the device from switch & chk arp again. Is the user connctd experiencing any probs?

[kian_hong2000]

I have copy another interface to help explain clearly.

1) I was not able to trace the mac-address on the switch port though the device is connected.

Cisco-XX-XX>sh mac-address-table interface fa0/2

Mac Address Table

-------------------------------------------

Vlan Mac Address Type Ports

2) Can you explain why mac add is not able to trace?

Does it relate to the Input/Output packets as follow :

FastEthernet2 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 0017.5a18.2608 (bia 0017.5a18.2608)

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

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

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

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

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

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

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

Last clearing of "show interface" counters 06:17:09

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

0 packets input, 0 bytes, 0 no buffer

Received 245 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 213 multicast, 0 pause input

0 input packets with dribble condition detected

122772 packets output, 19910316 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