Connecting 7705 with a Cisco CPE via T1

[Michael_Wu]

Does anybody have the experience of connecting 7705 with Cisco router by T1 port? On 7705, MDA is a 16-port T1/E1 card (a16-chds1), on Cisco 1720, it's the T1 CSU/DSU WIC.

7705 shows:
1/2/4 Up Yes Link Up
1/2/4.1 Up Yes Link Up 1502 1502 - accs ipcp tdm

but actually channel-group is not up:
===============================================================================
TDM DS0 Chan Group
===============================================================================
Description : DS0GRP
Interface : 1/2/4.1
TimeSlots : 1-24
Speed : 64 CRC : 16
Admin Status : up Oper Status : down

Also, 7705 sees input, but no output:
===============================================================================
Port Statistics
===============================================================================
Input Output
-------------------------------------------------------------------------------
Packets 1048 0
Discards 0 0
Unknown Proto Discards 0

Cisco shows:
==========
Serial1 is up, line protocol is down

0 packets input, 0 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 1 giants, 0 throttles
199 input errors, 2 CRC, 191 frame, 0 overrun, 0 ignored, 6 abort
1473 packets output, 20622 bytes, 0 underruns

Port configuration:
================
7705
------
port 1/2/4
tdm
ds1
channel-group 1
encap-type ipcp
timeslots 1-24
no shutdown
exit
no shutdown
exit
exit
no shutdown
exit

Cisco
-------
interface Serial1
ip address 192.168.140.2 255.255.255.0
encapsulation ppp
end

[Michael_Wu]

Apparently, 7705 receives packets. The problem is why it doesn't send out any?

===============================================================================
Traffic Statistics
===============================================================================
Input Output
-------------------------------------------------------------------------------
Octets 16352 0
Packets 1022 0
Errors 0 0

===============================================================================
Port Statistics
===============================================================================
Input Output
-------------------------------------------------------------------------------
Packets 1022 0
Discards 0 0
Unknown Proto Discards 0
===============================================================================[/font]

[mivens]

I don't have any direct experience of this but what does "show controller t1 ..." on the Cisco side say?
What about "show port 1/2/4.1 ppp detail" on the 7705?

As part of the troubleshooting, have you tried a different encap-type such as HDLC?