Category: Networking

Address Resolution Protocol (ARP) cache is a table where router or computer is keeping Layer 2 MAC addresses to Layer 3 IP addresses mappings which hw resolved lately. Without MAC to IP mapping the device would not be able to build and send IP packets.

Device discovers the MAC to IP mapping using ARP protocol Broadcast requests on the local subnet and saves the mapping in the ARP cache. If a device wants to send a packet to a neighbour, and it doesn’t have a corresponding MAC address, it sends out a broadcast ARP request packet. This broadcast packet reaches every device on the local subnet. Everybody will receive that ARP request packet but only the one device with the IP address mentioned in  ARP broadcast request packet responds back with an ARP response packet to complete the process.

If You want to create aliases on Cisco device for commonly used or complex commands we will show you how in this short configuration article.

You can create command aliases on your router with the alias command:

Port Numbers – How does Transport layer identifies the Conversations

Computers are today equipped with the whole range of different applications. Almost all of these applications are able in some way to communicate across the network and use Internet to send and get information, updates or check the correctness of user purchase. Consider they all these applications are in some cases simultaneously receiving and sending e-mail, instant messages, web pages, and a VoIP phone calls. In this situation the computer is using one network connection to get all this communication running. But how is it possible that this computer is never confused about choosing the right application that will receive a particular packet? We are talking about the computer that processes two or more communications in the same time for two or more applications running.

This is a list of Internet socket port numbers used by application communication with TCP and UDP on the Transport Layer of the Internet Protocol Suite for the host-to-host communications.

Let’s see who makes it possible? The Internet Assigned Numbers Authority (IANA) assigns all port numbers except Dynamic or Private ports. IANA is a standards organization in the world that is responsible for assigning various addressing standards.

There are different types of port numbers: Well Known Ports (Numbers 0 to 1023), Registered Ports (Numbers 1024 to 49151) and Dynamic or Private Ports (Numbers 49152 to 65535). The last porn number type Dynamic or Private Ports will not appear on our list because they are cannot be registered with IANA. This range is used for custom or temporary purposes and for automatic allocation of ephemeral ports. They are usually assigned dynamically to client applications when initiating a connection. It is not very common for a client to connect to a service using a Dynamic or Private Port, sometimes some peer-to-peer file sharing programs do.

Protocol-messaging solution – SMPP – Short Message Peer-to-Peer

Telecommunication industry’s protocol “SMPP” is used to exchange messages (SMS) between the peer entities e.g. short messages offering services centers. This protocol is capable to submit messages in bulk by a third party such as news organization. Anyhow, the main function of short message peer-to-peer protocol is to switch over the SMS messages between two be aware of each other entities.