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Determining live data vs overhead on atm interfaces

The scenario is an atm interface is up and the pvc status is up, but it has dropped from ospf and the circuit is suspected down. Yet the input packets keep incrementing (ex 9430 cells per minute), both INPkts and INPRoc by the same amount.

It seems like the traffic is more than keepalive, besides the ILMI-keepalive is turned off on the main interface.

How can I distinguish whether the cells received are live data from the remote site vs system overhead from the local atm switch? If I could do that, I could confirm that the circuit is the issue. Or is there another way to confirm the circuit is the issue?


Re: Determining live data vs overhead on atm interfaces

do you have oam configured on the pvc ? if not put it on both sides , then you will see the pvc go down , the traffic you see is most likely OAM streaming in from the switch

interface ATM0/0.1 point-to-point

pvc 2/401

oam-pvc manage

you can also do this command look at the F5 counters and the status

sh atm pvc 2/401

ATM4/0.401: VCD: 1, VPI: 2, VCI: 401, Connection

VBR-NRT, PeakRate: 155000, Average Rate: 20000, Burst Cells: 1000

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

OAM frequency: 10 second(s), OAM retry frequency: 1 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: 786 particles

VC Rx Limit: 1766 particles

InARP frequency: 15 minutes(s)

Transmit priority 4

InPkts: 62881115, OutPkts: 62629010, InBytes: 3433130546, OutBytes: 866896572

InPRoc: 106466, OutPRoc: 106465

InFast: 62774649, OutFast: 62522545, InAS: 0, OutAS: 0

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

InByteDrops: 0, OutByteDrops: 0

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

Out CLP=1 Pkts: 0

OAM cells received: 75584

F5 InEndloop: 75584, F5 InSegloop: 0, F5 InAIS: 0, F5 InRDI: 0

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

OAM cells sent: 75590

F5 OutEndloop: 75590, F5 OutSegloop: 0, F5 OutRDI: 0

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

OAM cell drops: 0

Status: UP

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