Can any one please clarify my doubts.
1.What is the difference between ethernet interface and serial interface?..( Both are giving 2 mbps,then what's difference)
2.Why we are configuring Controller configuration in router ?
controller E1 0/0/0
channel-group 0 timeslots 1-31
ip address x.x.x.x 255.255.255.252
ip ospf message-digest-key 70 md5 7 password
Thanks in advance
1) ethernet is a multi access technology that using Media Access Control allows to connect multiple devices. Each device is addressed by its MAC address. An ethernet frame has a destination MAC address, a source MAC address, protocol type that says what upper layer protocol is carried inside.
Ethernet does not use a TDM framing structure: when no traffic is sent there is silence. Each frame uses a 64 bits preamble to allow to potential receivers to sync with the frame. Between two distinct frames a mininum inter frame gap is needed this is equivalent of 12 bytes on wire.
Serial is point to point in nature, when synchronous there is a framing structure the frame header, there is no equivalent of MAC addresses (point-to-point)
A controller E1 object handles a PRI interface allowing to configure some aspects like linecode, CRC, framing type and how the B channels are used (one or more channel-groups can be configured). From controller configuration one or more serial interfaces objects are created like in your example.
It is a choice of IOS for this kind of modules that have many configurable parameters.
There are some other modules that haven't a controller object and use service-module commands in interface configuration mode to configure linecode and other E1 aspects.
Hope to help