1. Cisco Routers Routers collectively provide the main feature of the network layer—the capability to forward packets end-to-end through a network. routers forward packets by connecting to various physical network links, like Ethernet, serial links, and Frame Relay, and then using Layer 3 routing logic to choose where to forward each packet.

2. Installation of routers

3. Connected Routes A router adds routes to its routing table for the subnets connected to each of the router’s interfaces. For this to occur, the router must have an IP address and mask configured on the interface (statically with the ip address command or dynamically using Dynamic Host Configuration Protocol [DHCP]) and both interface status codes must be “up.” The concept is simple: If a router has an interface in a subnet, the router has a way to forward packets into that subnet, so the router needs a route in its routing table.

7. Although the connected routes on each router are important, routers typically need other routes to forward packets to all subnets in an internetwork. However, router can not reach the remote subnets because the router does not have remote subnets in it’s Routing table. So for this to work the administrator must configure a static route (routes that are configured manually. Static Routes

8. Configuration of static routes

9. The ping command The ping command sends an ICMP echo request packet to the stated destination address. The TCP/IP software at the destination then replies to the ping echo request packet with a similar packet, called an ICMP echo reply. The ping command sends the first packet and waits on the response. If a response is received, the command displays a “!”. If no response is received within the default timeout of 2 seconds, the ping command displays a “.”. The Cisco IOS software ping command sends five of these packets by default.