Cisco Compatible Micro Router Series

This document describes internal clocking and why you need it.

A. Internal clocking only applies to synchronous connections. Synchronous connections need a clocking signal to send and receive data. The vast majority of configurations will have this set to "Off". Normally, the circuit provider, the DSU, or the ISDN TA will be configured to supply the transmit data clock.

In the rare event that you do need internal clocking, such as connecting two routers back-to-back via a null modem cable, you need to make sure that internal clocking is set to "On" and set for the same clock rate, on both sides of the connection. Using CompatiView, check the "TX Clock Internal" checkbox under the relevant physical WAN port configuration dialog box (RS-232 or V.35), and specify a data rate, such as 64000. Using the command line, set the TxInternal keword to "On" under the relevant physical WAN interface ( RS232 Interface or V35 Interface ), and set the Baud keyword for that interface as well.

Special instructions are required for the following routers:

MicroRouter 900i and 1000R

1. Power off the router.

2. Unplug any attached cables.

3. Remove the two rear screws from the router.

4. Slide the router out of it's casing, towards the rear.

5. From the factory, the jumper will be on EXT . Looking at the rear of the motherboard, the jumper is labeled:

   WAN XMT CLK
   INT     EXT
   

6. Remove it and put it on INT .

7. Replace the cover and screws.

8. Reconnect cables.

9. Power router on.

10. Configure the router for Internal Clocking via CompatiView or the Command Line.

RISC Router 2800i and 3400R

1. Power off the router.

2. Unplug any attached cables.

3. Remove the four small screws on the left and right sides of the router.

4. Remove the four screws on the top of the router (towards the rear).

5. Slide the top cover off.

6. Look for jumper block P8. It's towards the rear of the router near the V35 connectors. There will be two jumper shunts placed on only one pin each

7. Move these two jumper shunts so that they cover two pins.

8. Replace the cover and screws.

9. Reconnect cables.

10. Power router on.

11. Configure the router for Internal Clocking via CompatiView or the Command Line.