Cisco Cisco IOS Software Release 12.0(15)S

The 6-port and 12-port E3 line cards consist of high-density E3 service through six or twelve E3 
interfaces.

The 6-port line card is a partially depopulated version of the 12-port line card. The 6-port line card 
consists of a total of 12 connectors, numbered 0 to 5. The 12-port line card consists of a total of 24 
connectors, numbered 0 to 11. A single port consists of one coaxial connector for receiving (RX) and 
one coaxial connector for transmitting (TX). 

The following sections provide procedures and examples that describe how to configure and verify 
6-port and 12-port E3 line card configuration:

You can configure the 6-port and 12-port E3 line cards in a Cisco 12000 Series Router with another 
device by using a data service unit (DSU) that supports either of the two third-party DSU vendors: 
Digital-Link and Kentrox. If you use a DSU to make the connection between the router and another 
device, you must set the DSU mode on the local E3 port configuration to match the DSU mode on the 
remote E3 port configuration. The configuration example on the left in 

 shows the 6-port or 

12-port E3 line card in a router connected to a Cisco 7200 Router with a high-speed serial interface 
(HSSI) port through an external DSU. 

If you make a direct connection between a Cisco 12000 Series Router and another device, you must set 
the local E3 port and the remote E3 port to the Cisco DSU mode, because there is no intervening 
third-party DSU. The configuration example on the right in 

 shows the Cisco DSU mode.