Routing

1. Routers runs have an operating system called IOS which means it is software-based processing device.

2. However, they are CEF-enhanced (cisco express forwarding). It is an attempt to use hardware  (e.g. cache) for forwarding packets

3. Router have Aux port which is not in Switch

4. Routers ports are down by default. Unlike switch, which can be used out of box.

5. In early days, CSU/DSU used to connect ISP line to serial port on router. However, CSU/DSU was not merely a converter and use to run many functions related to diagnostics of ISP line.

6. Now-a-days, we have other connection type and don’t require CSU/DSU.

 

INITIAL Router CONFIG:

In global configuration mode,

1. Hostname: hostname

2. Password:

• console and AUX
  • line console 0
  • password <set password>
  • login [Ask this password during login]
• telnet
  • line vty 0 15
  • password <set password>
• enable password
  • enable password or enable secret
  • if password is already specified in plain text using enable password, set type 7 encryption
    • service password-encrption

3. Management:

• setipaddres on connectedinterfacev
  • interface fa 0/1
  • ip address
  • no shutdown
• Set default gateway :
  • ip default-gateway
• Better to set default route (as router itself is default gateway):
  • ip route 0.0.0.0 0.0.0.0 <ip>/<exit-interface>

4.  Banner and Save

• bannermotd <>
  • banner login <> : for SSH and telnet (vty lines only)
• #copy run start  or # wr memory or #wr

5. Extra stuff to configure

• for lab environment, on line console 0
  • no exec-timeout   OR   exec-timeout 0 0
  • if a command typing is interrupted by syslog then repaint command: logging synchronous

6. Handy stuff to remember

• use negate command to nullify/remove a configuration: use no in front of command
• for filtering configuration file, use pipe and keyword
  • sh run | begin line con
• filter are smart and work without pipes on interfaces
  • sh run interface fa 0/1