Hi all
i have some questions about overrun count in show interface gix/y.
first, overrun is defined as the below
"receiver hardware is unable to hand received data to a hardware buffer because the input rate
exceeds the receiver's ability to handle the data.
This occurs due to a limitation of the hardware. Overruns occur when the internal First In,
First Out (FIFO) buffer of the chip is full, but is still tries to handle incoming traffic. The
receiver hardware is unable to hand received data to a hardware buffer because the input rate
exceeds the receiver's ability to handle the data."
=> how remote side(remote switch or router) can transmit traffic more than local switch(or router) can handle?
both sides line speed will shared, so they can transmit traffic up to line speed(ex. 1000Mbps)
in my lab,
pc or server or simulator ------------------- SW#1(Cat3560G) --------------------------SW#2(Cat4507)----------------------------- internet or some other network
sw#1 sh int
C3560G_4F# sh int gi 0/19
GigabitEthernet0/19 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet, address is 001b.0cc7.6913 (bia 001b.0cc7.6913)
Description: ### LTE_BB_SW(Cat4507) ###
MTU 1500 bytes, BW 1000000 Kbit/sec, DLY 10 usec,
reliability 255/255, txload 19/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/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 00:00:08, output hang never
Last clearing of "show interface" counters 17:01:02
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 71
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 7599000 bits/sec, 948 packets/sec
30 second output rate 78124000 bits/sec, 11926 packets/sec
63004229 packets input, 81046904171 bytes, 0 no buffer
Received 5268 broadcasts (5268 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 5268 multicast, 0 pause input
0 input packets with dribble condition detected
14492811 packets output, 12187915995 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
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
=> output drops increased
sw#2 sho int
C4507#sh int gi 6/42
GigabitEthernet6/42 is up, line protocol is up (connected)
Hardware is Gigabit Ethernet Port, address is e8b7.48bf.84e9 (bia e8b7.48bf.84e9)
Description: <<< FEMTO_GW_L3SW >>>
MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 1000Mb/s, link type is auto, media type is 10/100/1000-TX
input flow-control is off, output flow-control is off
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:10, output never, output hang never
Last clearing of "show interface" counters 01:01:51
Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 1728
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 83000 bits/sec, 117 packets/sec
30 second output rate 2704000 bits/sec, 1439 packets/sec
20505737 packets input, 16753097935 bytes, 0 no buffer
Received 4008 broadcasts (4008 multicasts)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 2044 overrun, 0 ignored
0 input packets with dribble condition detected
12200471 packets output, 11133189351 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 output buffer failures, 0 output buffers swapped out
=> overrun count increased
SW#1_gi0/19 and SW#2_gi6/42 are connected respectively.
so two switches are connected with 1000Mbps, full-duplex
i think this means, sw#1 and sw#2 can transmit up to 1000Mbps with each other
so they can't excess tx/rx-speed=1000Mbps.
if my assumption is right, what's a reason of increased overrun count on sw#2?
sw#1 can transmit up to 1000Mbps to sw#2
so sw#2 would receive up to 1000Mbps.
of course, sw#2(Cat4507)'s interface can handle every data from sw#1(Cat3560G) up to 1000Mbps, right?
what does bring sw#2's overrun increase?
sw#2 doen't have processing power for 1000Mbps traffic?
how do I approach this concept?
