Cisco Support Community
Community Member

Speed of link between devices on 3750 switch

I just acquired the administration of a small network with some Cisco 3750 switches which are in a stack configuration. We have IP phones and workstations/servers on these switches which were configured prior to my arrival. With new servers and workstations on these switches we are experiencing extremely slow data transfer from workstation to server or server to server. I checked duplex and speed settings for the affected ports and that looks fine. I also checked for errors on the ports and there are none. Below is the interface configuration, sh int and sh mls qos int output. The config and output is the same for all 5 interfaces which we are having a problem. I’m not up to speed with QoS and CoS and was wondering if that’s possibly the issue and would greatly appreciate any help and guidance.
Thank you,

interface FastEthernet1/0/31
switchport voice vlan 10
srr-queue bandwidth share 10 10 60 20
srr-queue bandwidth shape  10  0  0  0
mls qos trust device cisco-phone
mls qos trust cos
auto qos voip cisco-phone
spanning-tree portfast

3750switch#sh int f1/0/31
FastEthernet1/0/31 is up, line protocol is up (connected)
  Hardware is Fast Ethernet, address is 0018.b9a4.0aa3 (bia 0018.b9a4.0aa3)
  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 00:00:40, 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)
  5 minute input rate 0 bits/sec, 0 packets/sec
  5 minute output rate 31000 bits/sec, 10 packets/sec
     151346 packets input, 14904634 bytes, 0 no buffer
     Received 1335 broadcasts (0 multicast)
     0 runts, 0 giants, 0 throttles
     1 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     107419844 packets output, 637121213 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

3750switch#sh mls qos int f1/0/31
trust state: not trusted
trust mode: trust cos
trust enabled flag: dis
COS override: dis
default COS: 0
DSCP Mutation Map: Default DSCP Mutation Map
Trust device: cisco-phone
qos mode: port-based

Cisco Employee

Re: Speed of link between devices on 3750 switch


Can you remove all QoS settings from the server ports? Since server traffic

will be regular traffic on the switch, you do not need to regulate it using

QoS settings.



Community Member

Re: Speed of link between devices on 3750 switch

Thank you for the response. Do you suspect the QoS configuration to be suspect with our issue? If so, I would appreciate some technical info as to help me understand the QoS setup on this switch.

Thanks again,


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