I'm trying to setup a T3 between a Cisco 7500 and 3640 in the same room
just to get the gear tested before deploying it. The 7500 is using a
couple of PA-2T3's. The 3640 has an NM-1HSSI and a Kentrox T3 IDSU. I've
got a pair of short coax cables (maybe 4 feet) going from xmit to rcv
between one of the PA-2T3 T3 interfaces and the IDSU.
I'm having trouble getting the T3 to run 100% clean. After playing with
lots of settings, I think I've found that the IDSU and and PA-2T3 don't
get along with scrambling enabled. The link will work, but takes lots of
errors.
With the framing on each end set to c-bit, one end set to get clock from
the line, one set to internal, and scramble off, I can pass lots of
traffic...but I get small numbers of receive CRC errors on the 7500.
Router#sh in s2/0/1
Serial2/0/1 is up, line protocol is up
Hardware is cyBus PODS3 Serial
Internet address is 10.255.255.1/30
MTU 1500 bytes, BW 44210 Kbit, DLY 200 usec, rely 255/255, load 1/255
Encapsulation HDLC, crc 16, loopback not set
Keepalive set (10 sec)
Last input 00:00:00, output 00:00:00, output hang never
Last clearing of "show interface" counters 01:12:00
Queueing strategy: fifo
Output queue 0/40, 0 drops; input queue 0/75, 0 drops
30 second input rate 0 bits/sec, 0 packets/sec
30 second output rate 0 bits/sec, 0 packets/sec
11311 packets input, 15123753 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 parity
10 input errors, 10 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
13387 packets output, 16452239 bytes, 0 underruns
0 output errors, 0 applique, 0 interface resets
0 output buffer failures, 0 output buffers swapped out
0 carrier transitions
LC=up CA=down TM=down LB=down TA=down LA=down
Router#sh contr ser 2/0/1
Serial2/0/1 -
Mx T3(2) HW Revision 0x3, FW Revision 3.9
Framing is c-bit, Clock Source is Line
Bandwidth limit is 44210, DSU mode 1, Cable length is 10
Data in current interval (673 seconds elapsed):
2 Line Code Violations, 0 P-bit Coding Violation
0 C-bit Coding Violation
0 P-bit Err Secs, 0 P-bit Sev Err Secs
0 Sev Err Framing Secs, 0 Unavailable Secs
1 Line Errored Secs, 0 C-bit Errored Secs, 0 C-bit Sev Err Secs
Total Data (last 4 15 minute intervals):
17 Line Code Violations, 8 P-bit Coding Violation,
8 C-bit Coding Violation,
6 P-bit Err Secs, 0 P-bit Sev Err Secs,
0 Sev Err Framing Secs, 0 Unavailable Secs,
14 Line Errored Secs, 6 C-bit Errored Secs, 0 C-bit Sev Err Secs
No alarms detected.
Configured for remote default subrate
I've tried replacing the T3 cables (made a new set). It seems to have
slightly more trouble with patterns of alternating 0's and 1's (0xAAAA)
than the default pattern or all 0's or all 1's.
Have I overlooked something?
-- ---------------------------------------------------------------------- Jon Lewis *jlewis@lewis.org*| I route System Administrator | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________
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