1. ARP – Address Resolution Protocol: Address Resolution Protocol is utilized to acquire the MAC address of a host from the IP address that is supplied. This happens by the device looking in the ARP cache to see if an IP address has a corresponding MAC address. If not, then the device broadcasts to all the hosts on the network that it needs the MAC address for the supplied IP address. Then, only the host with that IP address replies with a packet that contains the corresponding MAC address. This is then added to the ARP table for future reference.
If there is not host with a corresponding IP address, the packet is discarded. ARP occurs at layer 2 and layer 3 of the OSI model and at layer 2 and layer 3 of the TCP/IP model. Although ARP can be theoretically utilized in IPV6 because of variable length addressing, ARP is only utilized in IPV4 because IPV6 utilizes the Neighbor Discovery protocol. There are some devices that do not utilize ARP such as bridges and layer 2 switches.2. IPv6 – Internet Protocol version 6: Internet Protocol version 6 (IPv6) describes the communication process that computers utilize over a network.
IPv6 has several new capabilities as compared to IPv4 such as expanded addressing capabilities, simplification of the header format, more support for extensions and options, flow labeling capability and authentication and privacy capabilities. The number of address in IPv6 increases to 128 bits from 32 bits in IPv4. Also, the format of IPv6 addresses is changed to utilizing hexadecimal values instead of number values, as in IPv4.
IPv6 incorporates a function called neighbor discovery which enables nodes to communicate with each other by utilizing five Internet Control Message Protocol messages. These messages are router solicitation, router advertisement, neighbor solicitation, neighbor advertisement and redirect. IPv6 automates address configuration by sending out a query. If the query if answered, then the address is not unique and must be manually configured.
IPv6 resides in layer 3 of both the OSI model and the TCP/IP model. 3. IPSec – Internet Protocol Security: IPSec refers to Internet Protocol Security which utilizes cryptography to provide security for communication over the Internet. This secure communication is supported by data integrity, data confidentiality, data origin authentication, and replay protection. Two examples of the types of defenses IPSec provides against are data corruption and data theft. There are two mechanisms that protect data being sent over IPSec. These are Encapsulation Security Payload (ESP) and Authentication Header (AH).
IPSec is transparent to applications, is compatible with both IPv4 and IPv6, and is integrated at the network layer in the OSI and the TCP/IP models. 4. BGP – Border Gate Protocol: Border Gate Protocol is a scalable protocol that is utilized for routing.
BGP routing tables are smaller due to BGP utilizing classless interdomain routing. To speed up the routing process, if there are two different routes that have the same destination, BGP selects the route with greater weight. Another feature is BGP learns if a route is interior, exterior or incomplete. This allows BGP to detect if there is a routing loop. BGP also has a next-hop attribute which is the connection IP address which tells the router which path to take.
BGP is a protocol that is on the Network layer in both the OSI and TCP/IP models.5. UDP – User Datagram Protocol: UDP is User Datagram Protocol which allows unreliable transfer of datagrams at the transport level in both the OSI and TCP/IP models. Delivery of datagrams utilizing UDP are not guaranteed. UDP must still have a minimum protocol which must have a source and a destination internet address. This type of protocol is suitable for applications such as video streaming or voice over IP where reliability of the packets reaching their destination only marginally affects that service.
6. POP3 – Post Office Protocol version 3: POP3 is Post Office Protocol version 3. This allows for electronic mail to be sent to a host over a network. This is accomplished by a server listening over a network for a host to initiate a session. The POP3 server then sends a greeting. POP3 does have an authorization process that occurs after the POP3 servers sends a greeting. This is where the client must identify and verify itself. Once this is completed, a transaction state is then created where the host and server maintain a connection, exchanging data and commands until the connection is terminated.
The data and commands are sent utilizing TCP for reliability of transmission. POP3 mail is deleted from the server when the messages are sent but are stored by the host for access at a later time. POP3 is an application layer protocol in both the OSI and TCP/IP models.7. HTTPS – Hyper Text Transfer Protocol with SSL: HTTPS is utilized to secure communications between a client and a server over the internet. This enables an http client and an https server to send encrypted data over the internet utilizing Secure Sockets Layer (SSL). Initially, HTTPS was performed utilizing TLS, but SSL is now the protocol that is utilized.
HTTPS is initiated with a handshake from the host. When the handshake is completed, the client and server can then transfer data securely until the session is terminated. HTTPS occurs at the application level in the OSI and TCP/IP model.8. DHCP – Dynamic Host Control Protocol: Dynamic Host Control Protocol provides a mechanism to automatically or manually supply a resource with an IP address. DHCP also provides mechanisms to supply configuration information for resources. This protocol is utilized by a DHCP server which supplies the IP address and configurations, a client which utilizes the protocol to obtain an IP address and a relay agent which passes information between LAN nodes for DHCP servers and clients. DHCP is designed to allow static and non-static IP address to co-exist with each other.
DHCP resides at session layer in the OSI model which equates to the application layer in the TCP/IP model.9. SLIP – Serial Line Internet Protocol: SLIP is Serial Line Internet Protocol which defines how a point-to-point dedicated serial connection can operate.
This connection runs TCP/IP and is not an Internet Standard. SLIP is a simple protocol which consists of a frame to be sent. In the frame is the data to be sent and an END character. SLIP operates at Layer 2 of the OSI model and the Data Link Layer in the TCP/IP model. SLIP was created a long time ago and although it is still in use in some environments, SLIP is being replaced with PPP.10. ICMP – Internet Control Message Protocol: As defined by the IETF, ICMP is the Internet Control Message Protocol sends datagrams which include messages about sending those datagrams. This could include problems with sending those messages or ensuring packets are being routed to their correct destinations.
ICMP can be utilized to check if a port or a host is unreachable. Two examples of very common programs that utilize ICMP are ping and traceroute. ICMP operates at the network layer in the OSI and TCP/IP models.
