Poor Inbound Speed on Cisco 2960

[tmq626]

Hello,

I have 5x Cisco 2960 and 1x Cisco 2960G. All of them are using IOS Version c2960-lanbasek9-mz.122-55.SE6.bin

I'm having poor inbound speed with ALL of the Cisco 2960 (except 2960G) although the outbound speed is normal.

The port is 100Mbps Full-Duplex, but the max inbound speed on a single connection is around 35Mbps. With the 2960G, I can get max 1Gbps inbound speed on a single connection.

I checked everything and still not know why the 2960 switches can't get max 100Mbps inbound.

Anyone has any ideas?

Should I upgrade to the newer IOS?

Thank You!

Minh

[glen.grant]

  Sounds like your 100 meg connection,  1 side is half duplex which would mean both sides are not matched. Typically in a half duplex setting you will get about what you are seeing about 1/3 of the speed .  Check that both sides of the link are both set as auto or both sides are hardcoded to 100/full . You cannot say have the switch side as auto and then hardcode the client end , this causes duplex mismatches.

[tmq626]

Thanks for your reply. I checked and all switch ports are full-duplex. If I make 4-5 connections, I can pull 80Mbps inbound, but a single connection can't max or nearly max the 100Mbps port speed, while the 2960G can do this without problem.

Also, I can max the 100Mbps port speed with the testing servers locating near it. While testing with a server located a bit far, it can't max the port speed, but the 2960G can max 1Gbps without problem. It's very weird.

[tmq626]

#sh int fa0/8

FastEthernet0/8 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 0021.1cc9.9008 (bia 0021.1cc9.9008)

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

reliability 255/255, txload 86/255, rxload 2/255

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 never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 30202340

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 831000 bits/sec, 1486 packets/sec

5 minute output rate 33967000 bits/sec, 2826 packets/sec

1032688666 packets input, 79734935904 bytes, 0 no buffer

Received 26983 broadcasts (9103 multicasts)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 9103 multicast, 0 pause input

0 input packets with dribble condition detected

1974373184 packets output, 2867822141251 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 PAUSE output

0 output buffer failures, 0 output buffers swapped out

[tmq626]

I think I found the issue. I setup policy-map to ratelimit the port speed and enabled mls qos. If I disable mls qos, the inbound speed is very fast, max 100Mbps. But, it seems the ratelimit won't work if I disable mls qos. Any ideas on this?

[Leo Laohoo]

Total output drops: 30202340

Nope.  Your switch is pushing as hard as it can.  The downstream is not handling the speed.