HI, For my company I'm often asked to troubelshoot some packet loss inside a layer 2 network.
In my lab, I'm trying to work out ways to diagnose possible packet loss on Cisco Layer 2 switches but I really can't find a way to show that a switch is droppping packets , for example .
In my lab, I've got two hosts generating each 60Mbps of Multicast UDP stream , on f0/1 and f0/2
My querier and mrouter are located on f0/10 , so by default, my (snooping) switch will forward the multicast to this mrouter port f0/10.. which should totally saturate and drop a LOT of since the 100Mbps line rate cannot handle the 60+60 agreggated traffic.
In the example below, on a low end switch C2950 , I can see that the uplink doens;t report any drops or full queue , alhouthg it is saturated to nearly line rate ,
Here is what my show commands look like:
show version : IOS (tm) C2950 Software (C2950-I6K2L2Q4-M), Version 12.1(22)EA14, RELEASE SOFTWARE (fc1)
show int f0/1 | inc bit :
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
30 second input rate 62867000 bits/sec, 5728 packets/sec
show int f0/2 | inc bit :
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
30 second input rate 62524000 bits/sec, 5740 packets/sec
show int f0/10
FastEthernet0/10 is up, line protocol is up (connected)
Hardware is Fast Ethernet, address is 0015.fa7b.9dca (bia 0015.fa7b.9dca)
MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec,
reliability 255/255, txload 251/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full-duplex, 100Mb/s, media type is 100BaseTX
input flow-control is unsupported output flow-control is unsupported
ARP type: ARPA, ARP Timeout 04:00:00
Last input 00:00:44, output 00:00:01, output hang never
Last clearing of "show interface" counters never
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 98565000 bits/sec, 9009 packets/sec
240 packets input, 21718 bytes, 0 no buffer
Received 92 broadcasts (88 multicast)
0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
0 watchdog, 88 multicast, 0 pause input
0 input packets with dribble condition detected
9245722 packets output, 4062614621 bytes, 0 underruns
0 output errors, 0 collisions, 2 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
