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New Member

High amount of output drops on cat 6500 gig link

Have a solution for a customer where we experience a high amount of drops on a gigabit interface facing a WAN router (from a service provider).

The interface on the WAN router is also gigabit Ethernet.

The solution is redundant with 2 x 6500 on the LAN side (acting as distr switches in the LAN) and 2 x 3845 from the service provider.

We run BGP towards the SP.

On the primary router we see a very large amount of output drops (increasing in bursts sometimes 5000-6000 in 1 sec). BUT when we force the traffic to the redundant 6500/3845 we DO NOT see any output drops despite the configuration are identical.

We have tried:

  • Swapping cables
  • Chaning interface speed/duplex to fixed
  • Setting flow control on/off
  • Changing to other Gig interface on different asic

For the moment we just steer the traffic via the redundant (secondary) switch/router to avoid routing the traffic through the interface with high drop rate.

There are no drops on the primay side when traffic is steered via secondary (of course).

The utilization of the links between WAN and LAN are low ( < 10 Mbps)

QoS are enabled on the 6500's

Port config:

interface GigabitEthernet3/41
description SP router

switchport
switchport trunk encapsulation dot1q
switchport trunk allowed vlan 17,101,103
switchport mode trunk
load-interval 30
mls qos trust dscp
end

IOS version is 12.2.33SXH3 on both 6500's

Linecard type is 6748 with CFC

Anybody have a clue why we see output drops on the primary side (and not on secondary)?

6500_drops_drawings.gif

Everyone's tags (3)
4 REPLIES
Hall of Fame Super Gold

Re: High amount of output drops on cat 6500 gig link

Can you post the "sh interface ", "sh interface counters errors module "?

Hall of Fame Super Blue

Re: High amount of output drops on cat 6500 gig link

In addtion to Leo's request, are the 6748 modules populated the same way on both chassis and if not could you describe the difference ?

Jon

New Member

Re: High amount of output drops on cat 6500 gig link

Note that we also had outdiscards on g3/41 when we transferred the traffic to that interface. The counters on 3/41 was cleared though.

3/16 is now down since the link is over on 3/41. And since the traffic not is routed through core02 the output drops does not increase on 3/41 (almost no traffic - just routing information).

Notable is also that we have not had any output drops on the link on core02 since yesterday.

core-01#sho int g3/16
GigabitEthernet3/16 is down, line protocol is down (notconnect)
  Hardware is C6k 1000Mb 802.3, address is 0021.d8be.061f (bia 0021.d8be.061f)
  Description: testport mot Telenor sec ruter
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 0/255, rxload 0/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Auto-duplex, Auto-speed, media type is 10/100/1000BaseT
  input flow-control is off, output flow-control is off
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 12:57:59, output 12:58:10, output hang never
  Last clearing of "show interface" counters 13:32:00
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 168567
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 0 bits/sec, 0 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     667887 packets input, 161787037 bytes, 0 no buffer
     Received 3128 broadcasts (2958 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     1781915 packets output, 420871109 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

GigabitEthernet3/41 is up, line protocol is up (connected)
  Hardware is C6k 1000Mb 802.3, address is 0021.d8be.0638 (bia 0021.d8be.0638)
  Description: Telenor sec ruter
  MTU 1500 bytes, BW 1000000 Kbit, DLY 10 usec,
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 1000Mb/s, media type is 10/100/1000BaseT
  input flow-control is off, output flow-control is off
  Clock mode is auto
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:45, output 00:00:24, output hang never
  Last clearing of "show interface" counters 12:33:20
  Input queue: 0/2000/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/40 (size/max)
  30 second input rate 1000 bits/sec, 2 packets/sec
  30 second output rate 0 bits/sec, 0 packets/sec
     119152 packets input, 9986447 bytes, 0 no buffer
     Received 18164 broadcasts (15156 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 0 multicast, 0 pause input
     0 input packets with dribble condition detected
     735948 packets output, 52438168 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

sho int counters errors module 3

Port            Align-Err    FCS-Err   Xmit-Err    Rcv-Err UnderSize OutDiscards
Gi3/1                   0          0          0          0         0           0
Gi3/2                   0          0          0          0         0           0
Gi3/3                   0          0          0          0         0           0
Gi3/4                   0          0          0          0         0           0
Gi3/5                   0          0          0          0         0           0
Gi3/6                   0          0          0          0         0           0
Gi3/7                   0          0          0          0         0           0
Gi3/8                   0          0          1          0         0           0
Gi3/9                   0          0          1          0         0           0
Gi3/10                  0          0          0          0         0           0
Gi3/11                  0          0          1          0         0           0
Gi3/12                  0          0          0          0         0           0
Gi3/13                  0          0          0          0         0           0
Gi3/14                  0          0          0          0         0           0
Gi3/15                  0          0          0          0         0           0
Gi3/16                  0          0          0          0         0      168567
Gi3/17                  0          0          0          0         0           0
Gi3/18                  0          0          0          0         0           0
Gi3/19                  0          0          0          0         0           0
Gi3/20                  0          0          0          0         0          11
Gi3/21                  0          0          0          0         0           0
Gi3/22                  0          0          1          0         0           0
Gi3/23                  0          0          1          0         0           0
Gi3/24                  0          0          1          0         0           0
Gi3/25                  0          0          0          0         0           0
Gi3/26                  0          0          0          0         0           0
Gi3/27                  0          0          0          0         0           0
Gi3/28                  0          0          0          0         0           0
Gi3/29                  0          0          0          0         0           0
Gi3/30                  0          0          0          0         0           0
Gi3/31                  0          0          0          0         0           0
Gi3/32                  0          0          0          0         0           0
Gi3/33                  0          0          0          0         0           0
Gi3/34                  0          0          0          0         0           0
Gi3/35                  0          0          0          0         0           0

Port            Align-Err    FCS-Err   Xmit-Err    Rcv-Err UnderSize OutDiscards
Gi3/36                  0          0          0          0         0           0
Gi3/37                  0          0          0          0         0           0
Gi3/38                  0          0          0          0         0           0
Gi3/39                  0          0          0          0         0           0
Gi3/40                  0          0          0          0         0           0
Gi3/41                  0          0          0          0         0           0
Gi3/42                  0          0          0          0         0           0
Gi3/43                  0          0          0          0         0           0
Gi3/44                  0          0          0          0         0           0
Gi3/45                  0          0          0          0         0           0
Gi3/46                  0          0          0          0         0           0
Gi3/47                  0          0          0          0         0           0
Gi3/48                  0          0          0          0         0           0

Port          Single-Col Multi-Col  Late-Col Excess-Col Carri-Sen     Runts      Giants
Gi3/1                  0         0         0          0         0         0           0
Gi3/2                  0         0         0          0         0         0           0
Gi3/3                  0         0         0          0         0         0           0
Gi3/4                  0         0         0          0         0         0           0
Gi3/5                  0         0         0          0         0         0           0
Gi3/6                  0         0         0          0         0         0           0
Gi3/7                  0         0         0          0         0         0           0
Gi3/8                  0         0         0          0         0         0           0
Gi3/9                  0         0         0          0         0         0           0
Gi3/10                 0         0         0          0         0         0           0
Gi3/11                 0         0         0          0         0         0           0
Gi3/12                 0         0         0          0         0         0           0
Gi3/13                 0         0         0          0         0         0           0
Gi3/14                 0         0         0          0         0         0           0
Gi3/15                 0         0         0          0         0         0           0
Gi3/16                 0         0         0          0         0         0           0
Gi3/17                 0         0         0          0         0         0           0
Gi3/18                 0         0         0          0         0         0           0
Gi3/19                 0         0         0          0         0         0           0
Gi3/20                 0         0         0          0         0         0           0
Gi3/21                 0         0         0          0         0         0           0
Gi3/22                 0         0         0          0         0         0           0

Port          Single-Col Multi-Col  Late-Col Excess-Col Carri-Sen     Runts      Giants
Gi3/23                 0         0         0          0         0         0           0
Gi3/24                 0         0         0          0         0         0           0
Gi3/25                 0         0         0          0         0         0           0
Gi3/26                 0         0         0          0         0         0           0
Gi3/27                 0         0         0          0         0         0           0
Gi3/28                 0         0         0          0         0         0           0
Gi3/29                 0         0         0          0         0         0           0
Gi3/30                 0         0         0          0         0         0           0
Gi3/31                 0         0         0          0         0         0           0
Gi3/32                 0         0         0          0         0         0           0
Gi3/33                 0         0         0          0         0         0           0
Gi3/34                 0         0         0          0         0         0           0
Gi3/35                 0         0         0          0         0         0           0
Gi3/36                 0         0         0          0         0         0           0
Gi3/37                 0         0         0          0         0         0           0
Gi3/38                 0         0         0          0         0         0           0
Gi3/39                 0         0         0          0         0         0           0
Gi3/40                 0         0         0          0         0         0           0
Gi3/41                 0         0         0          0         0         0           0
Gi3/42                 0         0         0          0         0         0           0
Gi3/43                 0         0         0          0         0         0           0
Gi3/44                 0         0         0          0         0         0           0
Gi3/45                 0         0         0          0         0         0           0
Gi3/46                 0         0         0          0         0         0           0
Gi3/47                 0         0         0          0         0         0           0
Gi3/48                 0         0         0          0         0         0           0

Port           SQETest-Err Deferred-Tx IntMacTx-Err IntMacRx-Err Symbol-Err
Gi3/1                    0           0            0            0          0
Gi3/2                    0           0            0            0          0
Gi3/3                    0           0            0            0          0
Gi3/4                    0           0            0            0          0
Gi3/5                    0           0            0            0          0
Gi3/6                    0           0            0            0          0
Gi3/7                    0           0            0            0          0
Gi3/8                    0           0            0            0          0
Gi3/9                    0           0            0            0          0

Port           SQETest-Err Deferred-Tx IntMacTx-Err IntMacRx-Err Symbol-Err
Gi3/10                   0           0            0            0          0
Gi3/11                   0           0            0            0          0
Gi3/12                   0           0            0            0          0
Gi3/13                   0           0            0            0          0
Gi3/14                   0           0            0            0          0
Gi3/15                   0           0            0            0          0
Gi3/16                   0           0            0            0          0
Gi3/17                   0           0            0            0          0
Gi3/18                   0           0            0            0          0
Gi3/19                   0           0            0            0          0
Gi3/20                   0           0            0            0          0
Gi3/21                   0           0            0            0          0
Gi3/22                   0           0            0            0          0
Gi3/23                   0           0            0            0          0
Gi3/24                   0           0            0            0          0
Gi3/25                   0           0            0            0          0
Gi3/26                   0           0            0            0          0
Gi3/27                   0           0            0            0          0
Gi3/28                   0           0            0            0          0
Gi3/29                   0           0            0            0          0
Gi3/30                   0           0            0            0          0
Gi3/31                   0           0            0            0          0
Gi3/32                   0           0            0            0          0
Gi3/33                   0           0            0            0          0
Gi3/34                   0           0            0            0          0
Gi3/35                   0           0            0            0          0
Gi3/36                   0           0            0            0          0
Gi3/37                   0           0            0            0          0
Gi3/38                   0           0            0            0          0
Gi3/39                   0           0            0            0          0
Gi3/40                   0           0            0            0          0
Gi3/41                   0           0            0            0          0
Gi3/42                   0           0            0            0          0
Gi3/43                   0           0            0            0          0
Gi3/44                   0           0            0            0          0
Gi3/45                   0           0            0            0          0
Gi3/46                   0           0            0            0          0

Port           SQETest-Err Deferred-Tx IntMacTx-Err IntMacRx-Err Symbol-Err
Gi3/47                   0           0            0            0          0
Gi3/48                   0           0            0            0          0

New Member

Re: High amount of output drops on cat 6500 gig link

The 6748's are not populated exactly the same. Though they have about 30 actice Gig ports each

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