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New Member

ATM Queueing and CRC Error Help

I am trying to work on the input errors and CRCs on the second interface below. The only difference I can see is the queueing strategy and the autovc creation on the second interface. The IOS for the top router is 12.2(8)T5 and the second one is 12.3(1).

ATM1/0 is up, line protocol is up

Hardware is ENHANCED ATM PA

MTU 4470 bytes, sub MTU 4470, BW 40704 Kbit, DLY 190 usec,

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

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5

4095 maximum active VCs, 85 current VCCs

VC idle disconnect time: 300 seconds

2 carrier transitions

Last input 00:00:04, output 00:00:00, output hang never

Last clearing of "show interface" counters 7w1d

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 71755

Queueing strategy: None

5 minute input rate 159000 bits/sec, 43 packets/sec

5 minute output rate 239000 bits/sec, 113 packets/sec

181861255 packets input, 2514855497 bytes, 133231 no buffer

Received 1001129 broadcasts, 0 runts, 0 giants, 0 throttles

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

639284334 packets output, 2243953228 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

The one giving trouble is this one:

ATM1/0 is up, line protocol is up

Hardware is ENHANCED ATM PA

MTU 4470 bytes, sub MTU 4470, BW 40704 Kbit, DLY 190 usec,

reliability 255/255, txload 5/255, rxload 1/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5

4095 maximum active VCs, 93 current VCCs

VC Auto Creation Disabled.

VC idle disconnect time: 300 seconds

2066 carrier transitions

Last input 00:00:10, output 00:00:00, output hang never

Last clearing of "show interface" counters 08:44:16

Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 929

Queueing strategy: Per VC Queueing

5 minute input rate 144000 bits/sec, 115 packets/sec

5 minute output rate 835000 bits/sec, 321 packets/sec

1786981 packets input, 400051114 bytes, 638 no buffer

Received 5809 broadcasts, 0 runts, 0 giants, 0 throttles

9714 input errors, 9714 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

7904022 packets output, 1634661120 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

The router that has no errors has per vc queue drops and the router that has errors under the atm interface has no per vc queue drops as shown below.

router with no CRC errors

Interface ATM1/0 VC 0/500

Queueing strategy: fifo

Output queue 0/40, 819 drops per VC

Interface ATM1/0 VC 0/32

Queueing strategy: fifo

Output queue 0/40, 863 drops per VC

Interface ATM1/0 VC 0/33

Queueing strategy: fifo

Output queue 0/40, 805 drops per VC

router with CRC errors

Interface ATM1/0 VC 0/31

Queueing strategy: fifo

Output queue 0/40, 0 drops per VC

Interface ATM1/0 VC 0/32

Queueing strategy: fifo

Output queue 0/40, 0 drops per VC

Interface ATM1/0 VC 0/33

Queueing strategy: fifo

Output queue 0/40, 0 drops per VC

Any help would be greatly appreciated.

  • Other Network Infrastructure Subjects
6 REPLIES
Silver

Re: ATM Queueing and CRC Error Help

can you paste in a 'sh atm pvc 0/31' 0/32, 0/33

I beleive you are overutinging your pvcs and you are getting AAl 5 errors that are being registered as CRC's

New Member

Re: ATM Queueing and CRC Error Help

sh atm pvc 0/31

ATM1/0.1: VCD: 1, VPI: 0, VCI: 31

UBR, PeakRate: 40704 (96000 cps)

AAL5-LLC/SNAP, etype:0x0, Flags: 0xC20, VCmode: 0x0

OAM frequency: 0 second(s), OAM retry frequency: 1 second(s)

OAM up retry count: 3, OAM down retry count: 5

OAM Loopback status: OAM Disabled

OAM Managed VC Status: Not Managed

ILMI Managed VC status: Not Managed

VC TxRingLimit: 40 particles

VC Rx Limit: 480 particles

InARP frequency: 15 minutes(s)

Transmit priority 6

InPkts: 5683, OutPkts: 23400, InBytes: 668093, OutBytes: 2282815

InCells: 16693, OutCells: 57028

InPRoc: 147, OutPRoc: 20053

InFast: 5536, OutFast: 3347, InAS: 0, OutAS: 0

InPktDrops: 0, OutPktDrops: 0/0/0 (holdq/outputq/total)

InCellDrops: 0, OutCellDrops: 0

InByteDrops: 0, OutByteDrops: 0

CrcErrors: 15, SarTimeOuts: 0, OverSizedSDUs: 0, LengthViolation: 0, CPIErrors: 0

Out CLP=1 Pkts: 0, Cells: 0

OAM cells received: 0

F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0

F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0

OAM cells sent: 0

F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0

F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0

OAM cell drops: 0

Status: UP

sh atm pvc 0/32

ATM1/0.2: VCD: 2, VPI: 0, VCI: 32

UBR, PeakRate: 40704 (96000 cps)

AAL5-LLC/SNAP, etype:0x0, Flags: 0xC20, VCmode: 0x0

OAM frequency: 0 second(s), OAM retry frequency: 1 second(s)

OAM up retry count: 3, OAM down retry count: 5

OAM Loopback status: OAM Disabled

OAM Managed VC Status: Not Managed

ILMI Managed VC status: Not Managed

VC TxRingLimit: 40 particles

VC Rx Limit: 480 particles

InARP frequency: 15 minutes(s)

Transmit priority 6

InPkts: 0, OutPkts: 22482, InBytes: 0, OutBytes: 2224152

InCells: 0, OutCells: 55205

InPRoc: 0, OutPRoc: 19982

InFast: 0, OutFast: 2500, InAS: 0, OutAS: 0

InPktDrops: 0, OutPktDrops: 0/0/0 (holdq/outputq/total)

InCellDrops: 0, OutCellDrops: 0

InByteDrops: 0, OutByteDrops: 0

CrcErrors: 34, SarTimeOuts: 0, OverSizedSDUs: 0, LengthViolation: 0, CPIErrors: 0

Out CLP=1 Pkts: 0, Cells: 0

OAM cells received: 0

F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0

F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0

OAM cells sent: 0

F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0

F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0

OAM cell drops: 0

Status: UP

#sh atm pvc 0/33

ATM1/0.3: VCD: 3, VPI: 0, VCI: 33

UBR, PeakRate: 40704 (96000 cps)

AAL5-LLC/SNAP, etype:0x0, Flags: 0xC20, VCmode: 0x0

OAM frequency: 0 second(s), OAM retry frequency: 1 second(s)

OAM up retry count: 3, OAM down retry count: 5

OAM Loopback status: OAM Disabled

OAM Managed VC Status: Not Managed

ILMI Managed VC status: Not Managed

VC TxRingLimit: 40 particles

VC Rx Limit: 480 particles

InARP frequency: 15 minutes(s)

Transmit priority 6

InPkts: 476, OutPkts: 21862, InBytes: 62473, OutBytes: 2308588

InCells: 1553, OutCells: 56762

InPRoc: 15, OutPRoc: 19099

InFast: 461, OutFast: 2763, InAS: 0, OutAS: 0

InPktDrops: 0, OutPktDrops: 0/0/0 (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: 0

F5 InEndloop: 0, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0

F4 InEndloop: 0, F4 InSegloop: 0, F4 InAIS: 0, F4 InRDI: 0

OAM cells sent: 0

F5 OutEndloop: 0, F5 OutSegloop: 0, F5 OutRDI: 0

F4 OutEndloop: 0, F4 OutSegloop: 0, F4 OutRDI: 0

OAM cell drops: 0

Status: UP

Silver

Re: ATM Queueing and CRC Error Help

the CRC error counter shown in this command is AAL 5 errors , what happens is you exceed your contracted rate and some cells are dropped. When the SAR is reassembling the cells in to ip packets there is some cells missing and the IP packet fails the CRC check. hence the crc counter increments ,

The only thing is that the crc's that are listed under your PVC does not match what your interface shows . Did you clear the counters prior to collecting these stats ?

You may want to look at the pvc's on the remote side also.

most of the time you can fix this issue by applying PCR & SCR values on the ATM PVC

pvc 0/31

ubr 6000 (if 6Mb is your contracted rate )

New Member

Re: ATM Queueing and CRC Error Help

I CRC error's do not match because there are over 100 pvc's and I just gave you three. I have cleared the counters on the ATM interface and the CRC's increment about 20 a minute. This is for a DSLAM.

Why wouldn't I get CRCs on the top interface without having the ubr 6000 statement? I will go ahead and read up on this and give it a try. Any other suggestions?

Silver

Re: ATM Queueing and CRC Error Help

I was just using 6000 as an example , you should traffic shape each side to match your contracted rate . This way you do not exceed your contracted rate , If you do not exceed your contracted rate then you will not get your cells tagged . refer to this URL

http://www.cisco.com/en/US/products/hw/modules/ps2033/products_implementation_design_guide_chapter09186a008019994d.html

New Member

Re: ATM Queueing and CRC Error Help

I will give it a try. Thanks for the information.

I am still confused why I am not having issues on the other router pvc's and the configuration is the same whether it is correct or not.

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