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To set the length of the cyclic redundancy check (CRC) on a T1 interface, use the following:
Purpose
Command
Enters global configuration mode.
Router#
configure terminal
Selects the interface to configure.
Router(config)#
interface serial
slot/subslot/port:channel-group
Selects the CRC size in bits.
•
16
—
16-bit CRC. This is the default
•
32
—
32-bit CRC.
Router(config-if)#
crc {16 | 32}
Verifying the CRC Size
Use the show interfaces serial command to verify the CRC size set on the interface:
Router# show interfaces serial 6/0/0:0
Serial6/0/0:0 is up, line protocol is up
Hardware is SPA-T1E1
MTU 1500 bytes, BW 1536 Kbit, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation PPP, crc 32, loopback not set
Keepalive set (10 sec)
LCP Open, multilink Open
Last input 00:00:38, output 00:00:00, output hang never
Last clearing of "show interface" counters 01:46:16
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 0 bits/sec, 0 packets/sec
1272 packets input, 20396 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicast)
0 runts, 0 giants, 0 throttles
6 input errors, 3 CRC, 0 frame, 0 overrun, 0 ignored, 3 abort
1276 packets output, 20460 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions no alarm present
Timeslot(s) Used:1-24, subrate: 64Kb/s, transmit delay is 0 flags
Configuring FDL
Facility Data Link (FDL) is a 4-kbps channel provided by the Extended Super Frame (ESF) T1 framing format.
The FDL performs outside the payload capacity and allows you to check error statistics on terminating
equipment without intrusion.
Purpose
Command
Enters global configuration mode.
Router#
configure terminal
Selects the controller to configure and enters
controller configuration mode.
Router(config)#
controller t1 slot/subslot/port
Cisco ASR 1000 Series Aggregation Services Routers SIP and SPA Software Configuration Guide, Cisco IOS XE
Everest 16.5
OL-14127-17
231
Configuring the 8-Port Channelized T1/E1 Serial SPA
Optional Configurations