Term
| DoD (Department of Defense) Model |
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Definition
| Condensed version of the OSI Model formed by 4 layers instead of 7 |
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Term
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Definition
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Term
| TCP/IP Model and OSI Model |
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Definition
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Term
Process /Application Layer (Layer 4) protocols
- Telnet
- FTP
- SFTP
- TFTP
- SMTP
- POP
- IMAP4
- RDP
- TSL
- SIP
- RTP
- SNMP
- SSH
- HTTP
- HTTPS
- NTP
- SCP
- LDAP
- IGMP
- DNS
- DHCP
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Definition
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Term
Comparison between OSI & DoD
& how TCP/IP fits both models |
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Definition
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Term
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Definition
Terminal emulation—remote login.
Allows a user on a remote client (Telnet client) to access the resources of another PC (Telnet server).
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Term
| FTP (FILE TRANSFER PROTOCOL) |
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Definition
Provides for single/multiple file transfers of files across an IP network |
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Term
| SFTP (SECURE FILE TRANSFER PROTOCOL) |
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Definition
Uses encrypted connection to transfer files. |
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Term
| TFTP (Trivial File Transfer Protocol) |
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Definition
| Stripped version for boot images |
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Term
| SMTP( Simple Mail Transfer Protocol) |
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Definition
Simple e-mail service between e-mail servers. Outbond mail (port 25). |
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Term
| POP (Post Office Protocol) - POP3 last version |
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Definition
Storage facility for incoming mail (port 110).
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Term
| IMAP4 (Internet Message Access Protocol v. 4) |
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Definition
–Replacing POP.
–Control how you download
incoming mail. |
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Term
| RDP (Remote Desktop Protocol) |
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Definition
GUI version of Telnet, implemented by Microsoft. |
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Term
| TLS ( Transport Layer Security) |
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Definition
–Enables secure online data-transfer.
–Internet Messaging, Internet Faxing. |
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Term
SIP (Session Initiation Protocol) |
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Definition
VoIP protocol used for signaling. |
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Term
| RTP (Real-time Transport Protocol) |
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Definition
VoIP protocol used for voice & video streams |
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Term
| SNMP (Simple Network Management Protocol) |
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Definition
–Collects info on network devices.
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Term
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Definition
Sets up secure Telnet session using encryption |
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Term
| HTTP (Hypertext Transfer Protocol) |
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Definition
Command/control between Web server and Web Browser.
Mechanism that opens a related document when you select a link.
HTTPS adds encryption & authentication for security
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Term
| NTP (Network Time Protocol) |
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Definition
Synchronizes network devices with atomic clock.
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Term
| SCP (Secure Copy Protocol) |
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Definition
Secure version of FTP.
Uses encryption |
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Term
| LDAP (Lightweight Directory Access Protocol) |
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Definition
An application protocol for querying and modifying directory services running over TCP/IP. |
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Term
| IGMP (Internet Group Management Protocol) |
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Definition
Manages IP multicast sessions |
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Term
| DNS (Domain Name Service) |
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Definition
Resolves host names to IP addresses. |
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Term
| DHCP (Dynamic Host Configuration Protocol) |
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Definition
Used by hosts (DHCP clients) to retrieve IP address assignments and other configuration information (dynamic IP configuration).
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Term
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Definition
- DHCP client broadcasts a DHCP Discover message to a DHCP server
- DHCP server sends a unicast DHCP OFFER message back to the host
- Client broadcasts to server a DHCP REQUEST message asking for the offered IP address
- Server sends a unicast DHCP ACKNOWLEDGMENT message.
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Term
| Host-to-Host Layer Protocols |
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Definition
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Term
| TCP (Transmission Control Protocol) |
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Definition
- Takes large block of information from an application and breaks them into segments.
- Numbers and sequences each segment so that the destination’s TCP process can put the segments back into the order the application intended.
- After these segments are sent, TCP (on the transmitting host) waits for an acknowledgment from the receiving end’s TCP process, retransmitting those segments that aren’t acknowledged.
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A device that wants to transmit sets up a connection-oriented communication with a remote device by creating a session. The trans- mitting device first establishes a connection-oriented session with its peer system; that ses- sion is called a call setup or a three-way handshake. Data is then transferred, and when the transfer is complete, a call termination takes place to tear down the virtual circuit.
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Term
| UDP (User Datagram Protocol) |
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Definition
Connectionless protocol, very fast, not reliable.
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Term
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Definition
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Term
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Definition
Numerical value that identifies application associated with the data.
Each port has unique 16-bit number of 0-65535.
–2 types of ports: TCP & UDP.
•Can use both ports simultaneously (multiplex).
•Client app protocols will know what port for a service.
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Term
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Definition
- Up to port 1023: Well-known port numbers
- 1024+:dynamic port numbers (originating-source ports dynamically assigned by source host)
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Term
Internet Layer Protocols
- IP (Internet Protocol)
- ICMP (Internet Control Message Protocol)
- ARP (Address Resolution Protocol)
- RARP (Reverse Address Resolution Protocol)
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Definition
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Term
IP (Internet Protocol)
Definition
Essentially is the Internet layer. The other protocols found here merely exist to support it. IP looks at each packet’s destination address. Then, using a routing table, it decides where a packet is to be sent next, choosing the best path. The protocols of the Network Access layer at the bottom of the DoD model deal only with physical links (local networks).
Identifying devices on networks requires answering these two questions: Which network is it on? And what is its ID on that network? The answer to the first question is the software address, or logical address (the correct street). The answer to the second question is the hardware address (the correct mailbox). All hosts on a network have a logical ID called an IP address. This is the software, or logical, address and contains valuable encoded information, greatly simplifying the complex task of routing.
IP receives segments from the Host-to-Host layer and fragments them into packets if necessary. IP then reassembles packets back into segments on the receiving side. Each packet is assigned the IP address of the sender and of the recipient. Each router (Layer 3 device) that receives a packet makes routing decisions based on the packet’s destination IP address.
•IP’s only job is to route data from A to B.
–Inserts its own header once it is received from TCP.
•Connectionless (no handshake).
–Must rely on TCP to determine if data arrived safely.
–IP is unreliable–TCP is reliable (see the relationship?).
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Term
| ICMP (Internet Control Message Protocol) |
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Definition
Provides Network layer management functions (ping command uses this).
The following are some common events and messages that ICMP relates to and the two most popular programs that use ICMP:
Destination Unreachable If a router can’t send an IP datagram any further, it uses ICMP to send a message back to the sender, advising it of the situation. For example, take a look at Figure 6.8, which shows that the Ethernet interface of the Lab B router is down.
When Host A sends a packet destined for Host B, the Lab B router will send an ICMP Destination Unreachable message back to the sending device (directly to Host A, in this example).
[image]
Buffer Full If a router’s memory buffer for receiving incoming datagrams is full, it will use ICMP to send out this message until the congestion abates.
Hops Each IP datagram is allotted a certain number of routers, called hops, to pass through. If a datagram reaches its limit of hops before arriving at its destination, the last router to receive it deletes it. The executioner router then uses ICMP to send an obituary message, informing the sending machine of the demise of its datagram.
Ping Ping uses ICMP echo request and reply messages to check the physical and logical connectivity of machines on an internetwork.
Traceroute Traceroute uses IP packet Time-to-Live time-outs to discover the path a packet takes as it traverses an internetwork.
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Term
| ARP (Address Resolution Protocol) |
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Definition
ARP is method for finding a host's hardware address when only its IP address is known.
Using ARP, an IP process creates a table to map logical addresses to hardware addresses of local network nodes.
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Term
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Definition
Discovers the identity of the IP address for diskless machines by sending out a packet that includes its MAC address and a request for the IP address assigned to that MAC address. A designated machine, called a RARP server, responds with the answer, and the identity crisis is over. RARP uses the information it does know about the machine’s MAC address to learn its IP address and complete the machine’s ID portrait.
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Term
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Definition
In summary, at a transmitting device, the data-encapsulation method works like this:
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User information is converted to data for transmission on the network.
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Data is converted to segments, and a reliable connection is set up between the transmitting and receiving hosts.
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Segments are converted to packets or datagrams, and a logical address is placed in the header so each packet can be routed through an internetwork.
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Packets or datagrams are converted to frames for transmission on the local network. Hardware (Ethernet) addresses are used to uniquely identify hosts on a local net- work segment.
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Frames are converted to bits, and a digital encoding and clocking scheme is used.
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