Routing Tables (SLP)
Assignment
You are required to review the SLP materials and conduct your own research (at least three additional sources of materials. Please be sure to use appropriate citations for materials that you collect on your own), in your own words, please write a 2- to 3-page paper (excluding the cover page and reference page) to describe the functions of routing tables based on the routing table structure.
Routing Table Structure
As illustrated in Figure 1, entries in the routing table usually consist of the following fields:
Routing Table Structure
Figure 1. Routing table structure
Network ID The Network ID field contains the identification number for a network route or an internetwork address for a host route.
Forwarding Address The Forwarding Address field contains the address to which the packet is to be forwarded. The forwarding address can be a network interface card address or an internetwork address. For network IDs to which the end system or router is directly attached, the Forwarding Address field may be blank.
Interface The Interface field indicates the network interface that is used when forwarding packets to the network ID. This is a port number or other type of logical identifier.
Metric The Metric field indicates the cost of a route. If multiple routes exist to a given destination network ID, the metric is used to decide which route is to be taken (best path). The route with the lowest metric is the preferred route.
Lifetime The Lifetime field indicates the lifetime that the route is considered valid. When routes are learned through the exchange of information with other routers, this is an additional field that is used. Learned routes have a finite lifetime. To keep a learned route in the routing table, the route must be refreshed through a periodic process. If a learned route’s lifetime expires, it is removed from the routing table. The timing out of learned routes provides a way for routers to reconfigure themselves when the topology of an internetwork changes due to a downed link or a downed router.
The Lifetime field is typically not visible in routing tables. Figure 10 shows another example of a routing table where Lifetime field is not visible.
Routing Table Structure 2
Figure 2. Routing table structure
Network Destination and Netmask together describe the Network ID (Figure 9) as mentioned earlier. For example, destination 192.168.0.0 and netmask 255.255.255.0 can be written as network id 192.168.0.0/24.
The Gateway column contains the same information as the Next hop (Forwarding Address in Figure 9), i.e. it points to the gateway through which the network can be reached.
The Interface indicates what locally available interface is responsible for reaching the gateway. In this example, gateway 192.168.0.1 (the internet router) can be reached through the local network card with address 192.168.0.100.
Finally, the Metric indicates the associated cost of using the indicated route. This is useful for determining the efficiency of a certain route from two points in a network. In this example, it is more efficient to communicate with the computer itself through the use of address 127.0.0.1 (called “localhost”) than it would be through 192.168.0.100 (the IP address of the local network card).
To learn more about set operations, check the following sites:
1.Routing Table (https://www.princeton.edu/~achaney/tmve/wiki100k/docs/Routing_table.html)
2.Routing Tables (http://technet.microsoft.com/en-us/library/cc957845.aspx)
3.Routing Table (http://www.hill2dot0.com/wiki/index.php?title=Routing_table)
4.What Is a TCP/IP Routing Table? (http://compnetworking.about.com/od/hardwarenetworkgear/f/routing_table.htm)
Your Paper should be between 2 and 3 pages (excluding the cover page and references page)