Reviewing the Ibternet Routing: Including Algorithms, Protocols, and Security

Explore the world of internet routing: how data packets navigate the complex network, from addressing and protocols to security risks and router trends.

Routing in the Internet and other networks (algorithms, standards, implementations, quality-of-service, security risks, router trends, etc.).

Overview of Routing

Routing is described by Zupan, Ramasamy & Medhi (2010) as enabling the electronic communication network to send packets or units of information from one point to another through a computer network. The network can achieve communications over the network quickly and efficiently.

Addressing is a core function of routing network communications from one point to another. A simple way to envision how networking functions is to compare it to how the US Postal Service processes mail from one location to another, as Zupan, Ramasamy & Medhi (2010) point out.

Postal service addressing is similar to Internet addressing, as Zupan, Ramasamy & Medhi (2010) describe.

The addressing used for the Internet is the Internet Protocol (IP). The IP address describes two things utilized in the postal service: the zip code and the house address. The Internet terminology for these terms translates into the netid and the hostid. They identify the network and the host address in the network. The host is the endpoint for communications. An endpoint for communication could be a web server or email server. The netid identifies the IP address block that identifies or defines the network. As Zupan, Ramasamy & Medhi (2010) describe, the postal services have a delivery mechanism to get the mail out by making deliveries using mail people in vehicles. The Internet does the same but delivers communications via transmission control protocol/Internet Protocol (TCP/IP), which relies on a delivery model that puts TCP in charge of providing the communicated information. At the same time, the IP is tasked with routing the communicated information or packets. The postal service would route a postcard to a house address, but the resident must deliver it to the correct person in the house, not the postal service.

A major difference in the Internet routing compared to the postal service is the sending host begins by first sending a beacon to the destination host to find out if it can be reached and awaits an acknowledgment before the data transmission of the message as Zupan, Ramasamy & Medhi (2010) points out. The beacon uses IP for transmission, but it may not reach the intended destination. To assist in the delivery of the beacon, a timer is used. The host that sends the beacon waits for a defined time to see if a response occurs.

If it does not hear back, then the beacon is set a few more times before hitting the maximum attempts. This means that when the sending host sends its beacon, it must also include its source IP address. Once the beacon process establishes connectivity between the sending host and receiving host, the transmission for the connection takes place. The receiving host should know the sending host's address so the recipient host can acknowledge the receipt of the beacon.

Once the connection occurs via the beacon process, the transmission of the content appears, as Zupan, Ramasamy & Medhi (2010) point out. Packets or datagrams can transmit the content. Using the example of downloading a 3 MB file from a web server, the IP may not allow all that data to fit in one packet. The limitation is known as the maximum transmission unit (MTU). The packets are labeled with the source and destination address, and the file can be broken up and transmitted. When sent over the IP network, these packets would have a timer associated with them. Once the packets arrive at the destination, they must be reassembled in the correct order to deliver the downloaded document.

After the packets are addressed as described in the example above, they then need to be routed from a source to the destination, as Zupan, Ramasamy & Medhi (2010) describe.

Routing may traverse many cross points, like driving a road and hitting an intersection. These cross points or intersections on the road are known as routers on a network. The router functions are to read the destination address of an incoming IP packet, check the internal routing tables and forward the packet. Similar to the number of lanes on a highway, the communications path between two routers is limited to the bandwidth that connects them.

The network then carries the traffic on its links through the routers to the eventual destination.

References

Zupan, J., Ramasamy, K., & Medhi, D. (2010). The morgan kaufmann series in networking: Network routing : Algorithms, protocols, and architectures Elsevier Science. Retrieved from https://shop.elsevier.com/books/network-routing/medhi/978-0-12-800737-2