- The Serial Line Internet Protocol (also SLIP) is an encapsulation of the Internet Protocol designed to work over serial ports and modem connections.
- SLIP is a TCP/IP protocol used for communication between two machines that are previously configured for communication with each other.
- For example, your Internet server provider may provide you with a SLIP connection so that the provider's server can respond to your requests, pass them on to the Internet, and forward your requested Internet responses back to you.
- A network interface controller (NIC, also known as a network interface card, network adapter, LAN adapter or physical network interface) is a computer hardware component that connects a computer to a computer network.
- The NIC allows computers to communicate over a computer network, either by using cables or wirelessly.
- The NIC is both a physical layer and data link layer device, as it provides physical access to a networking medium
- A network interface card provides the computer with a dedicated, full-time connection to a network. Personal computers and workstations on a local area network (LAN) typically contain a network interface card specifically designed for the LAN transmission technology
Aloha is a multiple access protocol at the data link layer that proposes how multiple terminals access the medium without interference or collision
Pure ALOHA :
- In pure ALOHA, the stations transmit frames whenever they have data to send.
- When two or more stations transmit simultaneously, there is collision and the frames are destroyed.
- In pure ALOHA, whenever any station transmits a frame, it expects the acknowledgement from the receiver.
- If acknowledgement is not received within specified time, the station assumes that the frame (or acknowledgement) has been destroyed.
- If the frame is destroyed because of collision the station waits for a random amount of time and sends it again. This waiting time must be random otherwise same frames will collide again and again
Slotted ALOHA :
- In slotted ALOHA, the time of the shared channel is divided into discrete intervals called slots.
- The stations can send a frame only at the beginning of the slot and only one frame is sent in each slot.
- In slotted ALOHA, if any station is not able to place the frame onto the channel at the beginning of the slot i.e. it misses the time slot then the station has to wait until the beginning of the next time slot.
When switch receives packets faster than the shared link can accommodate and stores in its memory for an extended period of time, then the switch will eventually run out of buffer space, and some packets will have to be dropped and in this state is said to congested state.
- Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography.
- Kerberos is a computer network authentication protocol that works on the basis of 'tickets' to allow nodes communicating over a non-secure network to prove their identity to one another in a secure manner.
- The Kerberos protocol uses strong cryptography so that a client can prove its identity to a server (and vice versa) across an insecure network connection.
- Kerberos protocol messages are protected against eavesdropping and replay attacks.
Internet Control Message Protocol (ICMP) :
- The Internet Control Message Protocol (ICMP) is a supporting protocol in the Internet protocol suite. It is used by network devices, like routers, to send error messages and operational information indicating, for example, that a requested service is not available or that a host or router could not be reached.
- ICMP differs from transport protocols such as TCP and UDP in that it is not typically used to exchange data between systems, nor is it regularly employed by end-user network applications
- ICMP (Internet Control Message Protocol) is an error-reporting protocol network devices like routers use to generate error messages to the source IP address when network problems prevent delivery of IP packets. ICMP creates and sends messages to the source IP address indicating that a gateway to the Internet that a router, service or host cannot be reached for packet delivery.
- ICMP messages are transmitted as datagrams and consist of an IP header that encapsulates the ICMP data. ICMP packets are IP packets with ICMP in the IP data portion. ICMP messages also contain the entire IP header from the original message, so the end system knows which packet failed
Denial of Service (DoS) :
- A denial-of-service attack is a security event that occurs when an attacker takes action that prevents legitimate users from accessing targeted computer systems, devices or other network resources.
- Denial-of-service (DoS) attacks typically flood servers, systems or networks with traffic in order to overwhelm the victim resources and make it difficult or impossible for users to use them.
- While an attack that crashes a server can often be dealt with successfully by simply rebooting the system, flooding attacks can be more difficult to recover from.
- In bidirectional communication, whenever a data frame is received, the receiver waits and does not send the control frame (acknowledgement) back to the sender immediately.
- The receiver waits until its network layer passes in the next data packet. The delayed acknowledgement is then attached to this outgoing data frame.
- This technique of temporarily delaying the acknowledgement so that it can be hooked with next outgoing data frame is known as piggybacking.
- If station A wants to send both data and an acknowledgment, it keeps both fields there.
- If station A wants to send just the acknowledgment, then a separate ACK frame is sent.
- If station A wants to send just the data, then the last acknowledgment field is sent along with the data. Station B simply ignores this duplicate ACK frame upon receiving .
- A gateway is a network node connecting two networks that use different protocols.
- Gateways can take several forms -- including routers or computers -- and can perform a variety of tasks.
- These range from simply passing traffic on to the next hop on its path to offering complex traffic filtering, proxies or protocol translations at various network layers.
Peer to Peer Network Model :
- A peer-to-peer (P2P) network is the one in which interconnected nodes ("peers") share resources among each other without the use of a centralized administrative system.
- It is network in which no node is a master or slave.
- Every node posses same capabilities and status There is no centralized server in the network, each node is itself a server and client.
- Peers make a portion of their resources, such as processing power, disk storage or network bandwidth, directly available to other network participants, without the need for central coordination by servers or stable hosts.