Information Technology Reference
In-Depth Information
Whatever the real problem is, a wrong CRC will be detected at the destination. The administrator of the
routers can detect this by checking the interface statistics. One CRC error results in an increment of input
error counter by 1 (see the previous note). The command
show interface atm (module/port)
illustrates
this behavior:
Medina#
sh int atm 3/0
ATM3/0 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 1/255, rxload 1/255
Encapsulation ATM, loopback not set
Keepalive not supported
Encapsulation(s): AAL5
4096 maximum active VCs, 2 current VCCs
VC idle disconnect time: 300 seconds Signalling vc = 1, vpi = 0, vci = 5
UNI Version = 4.0, Link Side = user
0 carrier transitions
Last input 00:00:07, output 00:00:07, output hang never
Last clearing of “show interface” counters never
Input queue: 0/75/0 (size/max/drops); Total output drops: 0
Queueing strategy: Per VC Queueing
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
104 packets input, 2704 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
32 input errors, 32 CRC
, 0 frame, 0 overrun, 0 ignored, 0 abort
106 packets output, 2353 bytes, 0 underruns
0 output errors, 0 collisions, 1 interface resets
0 output buffer failures, 0 output buffers swapped out
If the router has been configured for multiple PVCs, then relying only on the interface global counter
might not be very adequate. The input error counter might show that the traffic for multiple PVCs. In
this scenario, using the
sh atm pvc
vpi/vci
counters is recommended:
Medina#
sh atm pvc 0/36
ATM3/0.1: VCD: 4, VPI: 0, VCI: 36
VBR-NRT, PeakRate: 2000, Average Rate: 1000, Burst Cells: 32
AAL5-LLC/SNAP, etype:0x0, Flags: 0x20, VCmode: 0x0
OAM frequency: 0 second(s), OAM retry frequency: 1 second(s), OAM retry frequen)
OAM up retry count: 3, OAM down retry count: 5
OAM Loopback status: OAM Disabled
OAM VC state: Not Managed
ILMI VC state: Not Managed
InARP frequency: 15 minutes(s)
Transmit priority 2
InPkts: 24972, OutPkts: 25032, InBytes: 6778670, OutBytes: 6751812
InPRoc: 24972, OutPRoc: 25219, Broadcasts: 0
InFast: 0, OutFast: 0, InAS: 0, OutAS: 0
InPktDrops: 0, OutPktDrops: 0
CrcErrors: 0
, SarTimeOuts: 0, OverSizedSDUs: 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
