output drops o gig int

Sanjay Shaw · ‎09-28-2011

Hi,

Am not finding the resolution to my infrastucture and getting output drops. Sw1 is connected Sw2 as below stated

Please find the conf:

Sw 2 3750 conf:

interface GigabitEthernet1/0/46

no switchport

ip address 172.16.100.81 255.255.255.248

!

interface GigabitEthernet1/0/47

no switchport

ip address 10.72.250.200 255.255.255.0

standby 0 ip 10.72.250.210

!

interface GigabitEthernet1/0/48

no switchport

ip address 172.16.100.74 255.255.255.248

!

GigabitEthernet1/0/46 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 1cdf.0f89.83c1 (bia 1cdf.0f89.83c1)

Description: **** ****

Internet address is 172.16.100.81/29

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

reliability 255/255, txload 25/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/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 00:00:02, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 5206270

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 0 bits/sec, 0 packets/sec

5 minute output rate 10045000 bits/sec, 906 packets/sec

23445839 packets input, 13362109858 bytes, 0 no buffer

Received 4243815 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 4243682 multicast, 0 pause input

0 input packets with dribble condition detected

4016088554 packets output, 5526970378766 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 PAUSE output

0 output buffer failures, 0 output buffers swapped out

GigabitEthernet1/0/47 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 1cdf.0f89.83c2 (bia 1cdf.0f89.83c2)

Description: **** ****

Internet address is 10.72.250.200/24

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

reliability 255/255, txload 2/255, rxload 3/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/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 00:00:01, output hang never

Last clearing of "show interface" counters never

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 1090

Queueing strategy: fifo

Output queue: 0/40 (size/max)

5 minute input rate 1402000 bits/sec, 567 packets/sec

5 minute output rate 898000 bits/sec, 1297 packets/sec

6542350264 packets input, 2288468001575 bytes, 0 no buffer

Received 10436050 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 10291195 multicast, 0 pause input

0 input packets with dribble condition detected

12679777185 packets output, 1605428478319 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

GigabitEthernet1/0/48 is up, line protocol is up (connected)

Hardware is Gigabit Ethernet, address is 1cdf.0f89.83c3 (bia 1cdf.0f89.83c3)

Description: **** *****

Internet address is 172.16.100.74/29

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 10/100/1000BaseTX

input flow-control is off, output flow-control is unsupported

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:02, output 00:00:02, 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 0 bits/sec, 0 packets/sec

8690674 packets input, 880185867 bytes, 0 no buffer

Received 4257355 broadcasts (0 IP multicasts)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 4257337 multicast, 0 pause input

0 input packets with dribble condition detected

131343910 packets output, 31366608834 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 PAUSE output

0 output buffer failures, 0 output buffers swapped out

sw 2950 ;

interface FastEthernet0/22

description c3750-sw1-pt46

switchport access vlan 781

switchport mode access

spanning-tree portfast

!

interface FastEthernet0/23

description c3750-sw1-pt48

switchport access vlan 780

switchport mode access

spanning-tree portfast

!

interface FastEthernet0/24

description c3750-sw1-pt47

switchport access vlan 790

switchport mode access

spanning-tree portfast

FastEthernet0/22 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 000e.83db.c3d6 (bia 000e.83db.c3d6)

Description: c3750-sw1-pt46

MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,

reliability 255/255, txload 1/255, rxload 8/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:00, 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)

5 minute input rate 3269000 bits/sec, 263 packets/sec

5 minute output rate 2000 bits/sec, 3 packets/sec

397114259 packets input, 1378072999 bytes, 0 no buffer

Received 183700 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 183346 multicast, 0 pause input

0 input packets with dribble condition detected

224748880 packets output, 1847373962 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

FastEthernet0/23 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 000e.83db.c3d7 (bia 000e.83db.c3d7)

Description: c3750-sw1-pt48

MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,

reliability 255/255, txload 1/255, rxload 1/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s

input flow-control is off, output flow-control is off

ARP type: ARPA, ARP Timeout 04:00:00

Last input 00:00:00, 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)

5 minute input rate 135000 bits/sec, 75 packets/sec

5 minute output rate 0 bits/sec, 0 packets/sec

155456069 packets input, 3381363039 bytes, 0 no buffer

Received 164405 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 164394 multicast, 0 pause input

0 input packets with dribble condition detected

25738128 packets output, 1455071616 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

FastEthernet0/24 is up, line protocol is up (connected)

Hardware is Fast Ethernet, address is 000e.83db.c3d8 (bia 000e.83db.c3d8)

Description: c3750-sw1-pt47

MTU 1500 bytes, BW 100000 Kbit, DLY 1000 usec,

reliability 255/255, txload 7/255, rxload 4/255

Encapsulation ARPA, loopback not set

Keepalive set (10 sec)

Full-duplex, 100Mb/s

input flow-control is off, output flow-control is off

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 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 1945000 bits/sec, 2007 packets/sec

5 minute output rate 2984000 bits/sec, 1106 packets/sec

2336656579 packets input, 1916806953 bytes, 0 no buffer

Received 4113631 broadcasts (0 multicast)

0 runts, 0 giants, 0 throttles

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

0 watchdog, 4112935 multicast, 0 pause input

0 input packets with dribble condition detected

3636496844 packets output, 1822207913 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

Switch1 2950	Interface	Conf	Vla	Connected to
	22		vlan 781	SW 2-C3750X-Gig 1/0/46
	23		vlan 780	SW2-C3750X-Gig 1/0/48
	24	10.72.250.78	vlan 790	SW2-C3750X-Gig 1/0/47

Kind reply would be helpful.

Leo Laohoo · ‎09-28-2011

1. You connect a switch to another switch and you enable portfast? Are you serious???

2. Why is your setup like this? You could've just link them all together and form an etherchannel or use one link and allow dot1q trunking and specify the VLAN to carry across the link.

Output drops happen when the interface (3750) trying to push the traffic starts to drop the payload because the remote end (2950) can't handle the inbound traffic.

Sanjay Shaw · ‎09-28-2011

Thanks for the reply.

To update you I would like to add few more poits.

We have two 3750 Switch and two 2950 Switch which are connected vice versa ports as stated above .

Can I hv any soln on the present architecture to prevent the output drops on 3750. I understand ur point that the 2950 switch is not able to handle the incoming packets.Please reply what are the conf changes require to hv a soln to this problem

Removing spanning tree port fast command can prevent the drops.

Note: I do not want to change the architecture.

Thanks in advance.

shehinpm1 · ‎09-29-2011

Hi sanjay,

in addition to leo's reply,your n/w design is not in good architect.why don't you create SVI for each subnet instead of creating route port.as leo suggested make etherchannel or single trunk b'n SWs to carry multiple vlan informations

pls rate if hepfull

shehin.pm

Leo Laohoo · ‎09-29-2011

Can I hv any soln on the present architecture to prevent the output drops on 3750.

This line does NOT make any sense with the next line below.

Note: I do not want to change the architecture.

Output drops, as explained in my first post, happens when the 3750 interface is shoving as much data as it can downstream to your 2950 but the 2950's downstream port can no longer handle the traffic. THIS is your prolblem.

In my personal and humble opinion, someone did a very terrible job with your so-called network. You have three links to both switches. All three links are not in etherchannel. Now THIS is the problem and the solution to your problem. If you convert and configure etherchannel then things might get better.

So you see, you need to change the "architecture". Trying to solve your output drops without addressing the underlying problem is like driving g0lf buggy in the highway and not doing anything about it.

Sanjay Shaw · ‎09-30-2011

Thanks Leo and Shehin I do agree your points and will do as per your suggestion. Will discuss if required.