output drops with interface utilization = 20% !!! in Sw 2960-S - Page 2

mohamed louhab · ‎05-20-2013

hi ,

i noticed the "output drops" increasing in interface gi 1/0/1 in my switch 2960-S although the utilization of my interface is between 20% and 50 %

SW__A#sh interfaces gigabitEthernet 1/0/1

GigabitEthernet1/0/1 is up, line protocol is up (connected)

MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,

reliability 255/255, txload 93/255, rxload 3/255

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 00:00:00, output 00:00:00, output hang never

Last clearing of "show interface" counters 00:10:00

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 78484

Queueing strategy: fifo

Output queue: 0/40 (size/max)

30 second input rate 14786000 bits/sec, 22426 packets/sec

30 second output rate 365630000 bits/sec, 42896 packets/sec

6584758 packets input, 575696417 bytes, 0 no buffer

SW__A#sh controllers gigabitEthernet 1/0/1 utilization

Receive Bandwidth Percentage Utilization : 3

Transmit Bandwidth Percentage Utilization : 50

SW_A#sh interfaces gigabitEthernet 1/0/1 | include Total output drops

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 585722

SW_A#sh controllers gigabitEthernet 1/0/1 utilization

Receive Bandwidth Percentage Utilization : 1

Transmit Bandwidth Percentage Utilization : 24

The IOS version is :

Switch Ports Model SW Version SW Image

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

* 1 28 WS-C2960S-24TD-L 12.2(55)SE5 C2960S-UNIVERSALK9-M

what is the cause of this issue ??

thank you

Leo Laohoo · ‎05-20-2013

Even if the other switch is sending pause frames, the 2960S is ignoring them,

Good point, Paolo.

mohamed louhab · ‎05-20-2013

Ok , thank you for all this explanation

so it 's possible to enable flow-control in the switch 2960s ?

thank you ,

mohamed louhab · ‎05-20-2013

hi ,

i have found it

interface Gi 1/0/1

flowcontrol receive on

flowcontrol send on

i will test that and i will send to you the result

thank you

mohamed louhab · ‎05-21-2013

Hi ,

when i activate "flowcontrol " on the interface ( by the command flowcontrol receive on) i noticed that the interfaces of the router ( ASR-1001) conneceted to this Switch Become "shut down " !!!!

I did not understand why??? !!

paolo bevilacqua · ‎05-21-2013

It doesn't really matter, as flow control does not help at in case of output drops.

mohamed louhab · ‎05-20-2013

Hi ,
Yes the qos is disabled in the switch.

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