CCNAStudyGuide(1)
添加时间: 2007-9-3 22:47:43 作者: Cisco认证考试 阅读次数:61 来源: http://www.d9soft.com
Access list
1-99 IP standard
100-199 IP extended
200-299 Protocol type code
300-399 DECnet access list
400-499 XNS Standard Access
500-599 XNS Extended Access
600-699 AppleTalk
700-799 48 bit MAC address
800-899 IPX
900-999 IPX Extended
1000-1099 IPX SAP
1100-1199 Extended 48 bit MAC address
1200-1299 IPX summary address
Port numbers
TCP=6
UDP=17
FTP=21
TELNET=23
SMTP=25
DNS=53
TFTP=69
SNMP=161
NOVEL IPX Frame Type
Interface
Novell Frame Type
Cisco Keyword
Ethernet
Ethernet 802.3 and NetWare 3.11
Novell Ether
IPX Ethernet Encapsulation
Ethernet 802.2 and NetWare 3.12
SAP
Ethernet II
ARPA, DECnet and supports TCP/IP, IPX and upper layers
Ethernet SNAP
SNAP, AppleTalk, IPX, and TCP/IP
Token Ring
Token Ring 802.
SAP
Token Ring_SNAP
SNAP
FDDI
FDDI SNAP
SNAP
FDDI 802.2
SAP
FDDI RAW
NOVELL-FDDI
DOD model
IP
DOD
Protocol
Application, Presentation, Session
Process Application
Telnet, FTP, LPD, SNMP, TFTP, SMTP, NFS, X WINDOW
Transport
Host to Host
TCP, UDP
Network
Internet
ICMP, BOOTP, ARP, RARP, IP
Data Link
Network Access
Ethernet, Fast Ethernet, Token Ring, FDDI
IPX Protocl Stack:
Application, Presentation, Session ?/span> RIP, SAP, NCP, NLSP, etc…
Transport ?/span> IPX, SPX
Network ?/span> IPX
Data link ?/span> ODL Open Data Link
Physical ?/span> whatever
OSI Model:
Transport is TCP Segments
Network is IP Packets/Datagrams
Data Link is Ethernet frames
Physical is Bits
The five steps to Encapsulation:
1. Build the data
2. Package data for end-to-end transport (Segments transport subsystem)
3. Append network address in header (data is put into a packet or datagram) Network
4. Append local address in data link header (must be put into a frame or packet) Data
5. Convert to bits for transmission 1 and 0 Physical
Data > Segment > Packet > Frame > Bits
Data Encapsulation Method
1. User information is converted to data for transmission on the network.
2. Data is converted to segments and packaged with control information for a reliable connection.
3. Segments are encapsulated with a network header and converted to packets or datagrams, which specify the source and destination logical addresses.
4. Packets, or datagrams, are converted to frames to allow a connection over an interface to the network.
5. Frames are converted to bits with some clocking functions to allow transmission a medium.
Key Terms:
Bits: The Physical layer takes the binary data down from the Data Link Layer and converts the 1’s and 0’s to a digital signal to be sent out over the physical topological.
Frames: These house the packets, or datagrams, handled down from the Network layer to be delivered to a device on a LAN.
Packets: Sometimes called datagrams, these house the segments handed down the
Transport layer to be routed through an internetwork.
Segments: Defined at the Transport layer, these are part of a data stream that is handed down from the upper layers to be transmitted to a destination device.
Ethernet Frame:
Preamble, DA, SA, Type, Data, FCS
OSI Model:
Application layer 7File, print, message, database, and applications. Determines availability of the target host. www, email, ftp, telnet, EDI, quake
Presentation layer 6
Text and Data Formatting, Data Encryption, Compression, and Translation services Determines the syntax of the data transfer. Pict, tiff, jpeg, midi, mpeg, quicktime, EBCDIC and ASCII
Session layer 5
Service Requests, Dialog control, coordinates the communications, Establishes, Manages, and terminates communication sessions between applications. Offers full or half-duplex define and group formatted data, and offers some session recovery or checkpoint mechanisms between the applications coordinated between the hosts. NFS, SQL, RPC, X Windows, ASP (appletalk session protocol), DNA SCP (digital whatzit)
Transport layer 4
***TCP uses Three-way handshake for Transport test question***
End-to-end communication, flow control provided by sliding windows, and error checking
Ensure Data Reliability provided by sequence numbers and acknowledgements
NBP Name Binding Protocol it associates with AppleTalk
Responsible for hiding the communications from the higher layers. TCP / UDP
Segment upper layer applications
Establish end-to-end operations
Send segments from one end host to another end host using checksum
Ensure data reliability and uses SPX protocol
Multiplexing: refers to the capability of multiple applications to share a transport connection.
Note: When datagrams arrive to quickly for a host or gateway they are stored in memory temporarily. If the datagrams are part of a small burst, this buffering solves the problem. If the traffic continues, the host or gateway eventually exhausts its memory and must discard additional datagrams that arrive.
Network layer 3
Routing IP, ICMP, BootP, ARP, RARP Routers Logical Addressing and network Addressing
To enable path determination, the routing service provide:
- Routing table initialization and maintenance
- Routing update processes and protocols
- Routing domains and address specifications
- Route metric assignment and control
Test Question:
Routing protocols uses network topology information when evaluating network paths. This information can be configured by the network administrator or collected through DYNAMIC processes running in the network.
Data Link layer 2
Framing Ethernet II, 802.5 (token ring), 802.3, 802.2 (802.3 with dsap and sap logical link control fields) Media access control: MAC: 48 bits, 3 bytes vendor + 3 bytes serial number
WAN:
CDP, ( Cisco Discovery Protocol) High-level datalink control HDLC (Cisco default for serial links) Synchronous Data Link Control SDLC (uses polling) Link Access Procedure, Balanced LAPB x.25, slip, PPP, isdn, Frame Relay, and Dial on Demand
Bridges / Switches
Link Layer address
SAP and LLC is used to define the upper layers. Provides flow control.
The addresses for which the MAC sublayer is responsible.
Physical layer 1
Wire… v.24, v.35, x.21, g.703, hssi, etc
Repeaters / Hubs
100BaseFX is ethernet over fiber optic
100BaseTX is Ethernet over Category 5 and Type 1 cabling.
Hardware addresses are used to get a packet from one local device to another local device.
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