Re: ATM troubleshoot.

amagu · ‎08-25-2004

Hi all,

I need some help with an ATM issue.

I do not know very well this WAN technologie, and i am facing a big problem.

In fact we have a PVC that is very slow.

I need to check and understand the parameter of our configuration.

Here are the details:

IN THE MOS SIDE :

================

!

interface ATM5/0.1 point-to-point

bandwidth 6000

ip address 16.35.42.230 255.255.255.252

ip access-group 108 in

ip access-group 109 out

ip pim sparse-mode

ip ospf cost 2000

pvc mosbbn1 3/150

vbr-nrt 12000 6000 200

oam-pvc manage 60

oam retry 5 10 10

encapsulation aal5snap

!

IN THE BBN SIDE:

=================

!

interface ATM4/0/0.2 point-to-point

bandwidth 6000

ip address 16.35.42.229 255.255.255.252

ip access-group 108 in

ip access-group 109 out

ip accounting access-violations

ip pim sparse-mode

pvc bbnmos 3/150

vbr-nrt 12000 6000 200

oam-pvc manage 60

oam retry 5 10 10

encapsulation aal5snap

!

.

Please can you help me to check the parameter with the carrier?

Best Regards,

smif101 · ‎08-25-2004

Normally you would put in the distant end IP address under the PVC such as this config

R2(config)#interface atm0.1 point-to-point

R2(config-if)#ip address 12.0.0.1 255.255.255.0

R2(config-if)#pvc 1 300

R2(config-if-vc)#protocol ip 12.0.0.2 broadcast

R2(config-if-vc)#encapsulation aal5snap

R3(config)#interface atm0.1 point-to-point

R3(config-if)#ip address 12.0.0.2 255.255.255.0

R3(config-if)#pvc 1 250

R3(config-if-vc)#protocol ip 12.0.0.1 broadcast

R3(config-if-vc)#encapsulation aal5snap

What does your ping look like end to end. Try it from 32 to 1500 bytes and see if you are dropping packets. I assume you will so from there I would try doing loopbacks to find out where the problem is.

dbellazetin · ‎08-25-2004

Actually you don't need to map the far end ip on point to point interfaces.

Are you seeing CRC's on your ATM interface/s?

Can you post "show int atm x" and "show atm pvc x/x"

Daniel

amagu · ‎08-26-2004

Hi Daniel,

Here are the results of the command:

mosgw1#sh int atm5/0.1

ATM5/0.1 is up, line protocol is up

Hardware is ENHANCED ATM PA

Internet address is 16.35.42.230/30

MTU 4470 bytes, BW 6000 Kbit, DLY 80 usec,

reliability 255/255, txload 2/255, rxload 6/255

Encapsulation ATM

49974 packets input, 30019875 bytes

43493 packets output, 15356135 bytes

2707 OAM cells input, 2707 OAM cells output

AAL5 CRC errors : 2

AAL5 SAR Timeouts : 0

AAL5 Oversized SDUs : 3

mosgw1#sh int atm5/0

ATM5/0 is up, line protocol is up

Hardware is ENHANCED ATM PA

MTU 4470 bytes, sub MTU 4470, BW 149760 Kbit, DLY 80 usec,

reliability 255/255, txload 2/255, rxload 6/255

Encapsulation ATM, loopback not set

Encapsulation(s): AAL5

4095 maximum active VCs, 2 current VCCs

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 22:26:54

Input queue: 0/75/4/279 (size/max/drops/flushes); Total output drops: 18

Queueing strategy: Per VC Queueing

1 minute input rate 3886000 bits/sec, 627 packets/sec

1 minute output rate 1296000 bits/sec, 546 packets/sec

22916680 packets input, 3874025835 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 3 giants, 0 throttles

378 input errors, 378 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

21701811 packets output, 3128735920 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 output buffer failures, 0 output buffers swapped out

mosgw1#

=========================================

mosgw1#show atm pvc 3/150

ATM5/0.1: VCD: 1, VPI: 3, VCI: 150, Connection Name: mosbbn1

VBR-NRT, PeakRate: 12000, Average Rate: 6000, Burst Cells: 200

AAL5-LLC/SNAP, etype:0x0, Flags: 0x20, VCmode: 0x0

OAM frequency: 60 second(s), OAM retry frequency: 10 second(s), OAM retry frequency: 10 second(s)

OAM up retry count: 5, OAM down retry count: 10

OAM Loopback status: OAM Received

OAM VC state: Verified

ILMI VC state: Not Managed

VC is managed by OAM.

VC TxRingLimit: 235 particles

VC Rx Limit: 141 particles

InARP frequency: 15 minutes(s)

Transmit priority 4

InPkts: 49985, OutPkts: 43529, InBytes: 30020385, OutBytes: 15358991

InPRoc: 6706, OutPRoc: 12802

InFast: 43279, OutFast: 30727, InAS: 0, OutAS: 0

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

CrcErrors: 2, SarTimeOuts: 0, OverSizedSDUs: 3, LengthViolation: 0, CPIErrors: 0

Out CLP=1 Pkts: 0

OAM cells received: 2715

F5 InEndloop: 2715, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0

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

OAM cells sent: 2715

F5 OutEndloop: 2715, F5 OutSegloop: 0, F5 OutRDI: 0

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

OAM cell drops: 0

Status: UP

mosgw1#

dbellazetin · ‎08-26-2004

You have CRC errors and Input Errors on your ATM 5/0 interface. I would suggest doing "clear counters atm 5/0" and then checking "show int atm 5/0" every few minutes to see if your CRC's and Input Errors are rising quickly. If they are that can be the issue.

A few things that can cause this type of problem.

1) Faulty ATM interface or ATM circuit

2) Traffic shaping is not configured properly (VBR-nrt). You may be transmitting more traffic than you are actually supposed to causing your provider to drop ATM cells. Double check your traffic agreement for your circuit.

3) ATM network is congested and the provider is dropping ATM cells.

I would do the following on both sides of the connection.

clear counters atm x

show int atm x (repeat every few mins. to watch CRCs)

This way you can see if maybe the problem is only in one direction or in both.

Hope this helps.

Daniel