CCNA study notes on TCP/IP

TCP/IP

1. Port numbers are used by TCP/ UDP to set up sessions with other hosts. The following are the recommended port numbers:

• Numbers 0 - 255 are used for public applications.

• Numbers 255 - 1023 are assigned to companies so that they can use these port numbers in their applications.

• Numbers above 1023 are used by upper layers to set up sessions with other hosts and by TCP to use as source and destination addresses.

2.The term Segments is usually associated with Transport layer

• The term Packets is usually associated with Network Layer and

• The term Frames is usually associated with Data Link Layer

3. TCP: TCP is a full-duplex, connection-oriented protocol. It incorporates error checking as well.

UDP (User Datagram Protocol): UDP is a thin protocol. UDP is a connectionless protocol. It doesn't contact the destination before sending the packet and doesn't care whether the packet is reached at the destination.

4. SNMP is part of TCP/IP protocol suite. It allows you to monitor and manage a network from a centralized place by using SNMP Manager software. The systems or devices that provide the responses are called agents (or MIBs). An SNMP agent is any computer running SNMP agent software.

MIB stands for Management Information Base. It is part of SNMP agent database. A MIB records and stores information about the host it is running on. An SNMP manager can request and collect information from an agent's MIB. Routers are typical MIB agents. SNMP agent generates "trap" messages that are then sent to an SNMP management console, which is a trap destination.

i. Telnet, FTP, and TFTP:

1. Telnet is used for terminal emulation that runs programs remotely. Telnet uses TCP/IP protocol.

2. Telnet requires a username and password to access.

3. FTP (File Transfer Protocol) is a connection oriented protocol. It uses TCP/IP for file transfer. Compare this with TFTP (Trivial File Transfer Protocol) that uses UDP (Connectionless protocol). SNMP uses UDP over IP. Tracert, Ping uses ICMP as their base protocol. FTP is used to transfer files.

Both FTP and Telnet are client-server protocols. Note that TCP/IP is a client server oriented protocol.

ii. HDLC

1. The High Level Data Link Control protocol (HDLC) is the default encapsulation used on the synchronous serial interfaces of a Cisco router. HDLC is a Data Link layer protocol used to encapsulate and transmit packets over point-to-point links.

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