One of our ATM links is reporting output drops:
show interfaces atm 1/0
ATM1/0 is up, line protocol is up
Hardware is ENHANCED ATM PA
Description: ATM TRUNK
MTU 4470 bytes, sub MTU 4470, BW 149760 Kbit, DLY 80 usec,
reliability 255/255, txload 5/255, rxload 2/255
Encapsulation ATM, loopback not set
Encapsulation(s): AAL5
4095 maximum active VCs, 3 current VCCs
VC Auto Creation Disabled.
VC idle disconnect time: 300 seconds
0 carrier transitions
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 1d15h
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 152699
Queueing strategy: Per VC Queueing
30 second input rate 1723000 bits/sec, 716 packets/sec
30 second output rate 3118000 bits/sec, 672 packets/sec
66722977 packets input, 568696940 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
62762717 packets output, 1367514775 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
Appears to be caused by one subint in particular:
#sh atm pvc 10/101
Description: N/A
ATM1/0.101: VCD: 2, VPI: 10, VCI: 101, Connection Name: QLD_C1
VBR-NRT, PeakRate: 14000 (33019 cps), Average Rate: 7000 (16510 cps)
Burst Cells: 94
AAL5-LLC/SNAP, etype:0x0, Flags: 0x20, VCmode: 0x0, Encapsize: 12
OAM frequency: 10 second(s), OAM retry frequency: 1 second(s)
OAM up retry count: 3, OAM down retry count: 5
OAM Loopback status: OAM Received
OAM VC Status: Verified
ILMI VC status: Not Managed
VC is managed by OAM.
VC TxRingLimit: 3 particles
VC Rx Limit: 165 particles
InARP frequency: 15 minutes(s)
Transmit priority 4
InPkts: 59112577, OutPkts: 62488267, InBytes: 906189222, OutBytes: 1355211759
InCells: 584410574, OutCells: 775588246
InPRoc: 57684, OutPRoc: 57595
InFast: 59054893, OutFast: 61150799, InAS: 0, OutAS: 0
InPktDrops: 0, OutPktDrops: 152699/0/152699 (holdq/outputq/total)
InCellDrops: 0, OutCellDrops: 0
InByteDrops: 0, OutByteDrops: 0
CrcErrors: 0, SarTimeOuts: 0, OverSizedSDUs: 0, LengthViolation: 0, CPIErrors: 0
Out CLP=1 Pkts: 0, Cells: 0
OAM cells received: 14272
F5 InEndloop: 14272, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0
F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0
OAM cells sent: 14272
F5 OutEndloop: 14272, F5 OutSegloop: 0, F5 OutRDI: 0
F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0
OAM cell drops: 0
Status: UP
From Cisco Site:
"Note: Any interface that is overdriven (that is, when the offered rate is greater than the line rate) presents output drops.
ATM interfaces typically use ATM-layer traffic shaping to limit the maximum amount of bandwidth used by a virtual connection. If you present more traffic to the virtual circuit (VC) than it is configured to transmit, the ATM interface tries to store the packet until it can be scheduled for transmission. However, the interface may need to drop some packets. This can particularly happen if you burst above the traffic-shaping parameters for a period of time longer than the virtual circuit is configured to handle. Traffic shaping is often implemented as part of a traffic contract with the circuit provider."
It is a 7Mb PVC (Burstable to 14Mb), and I've never seen the txload or rxload get over 9/255 - And our SolarWinds monitoring has never reported anything above 6Mb/sec? Just wondering what could be causing this?
7204 VXR with NPE400 (12.3-15)
Regards,
MB
