Ethernet_II -PreAmb8-DA6-SA6-Type2(upper layer proto ID)-Data-FCS 4 (Cyclic Redundancy Checksum).

802.2_Ethernet-PreAmb8-DA6-SA6-Length-DSAP-SSAP(802.2 LLC header)-Data-FCS.(MAC & LLC)

802.3_Ethernet-PreAmb8-DA6-SA6-Length-Data-FCS (MAC) (CSMA/CD-IEEE-802.3) can’t identify up layer protos.

Physical-defines Bit synch & Physical topology, Specs define such as voltage levels, timing of voltage changes, physical data rates, max trans distances, and the physical conntrs be used. Eg. FDDI, SONET, ISDN. (Stds: v.24, v.35, x..21, G.703 ), LAN-imples-Ethernet/IEEE 802.3, Fast Ethernet, FDDI, and Token Ring/IEEE 802.5.

WAN-imples- High-Speed Serial Interface (HSSI), SMDS Interface Protocol (SIP), and X.21bis.

10Base2-ThinNet-RG58-BNC-185 Mtrs, 100BaseT4-100MB,Cat 3/4/5, 802.3

10Base5-ThickNet-RG8-DIX/AUI-500Mts, 100 BaseTx-Cat5-STP-100 Mtrs.(Fast Enet over STP/802.3),

10BaseT-Cat3/4/5-100Mts. 100Base Fx-100MB,2 pr OFC 802.3

10/100Base FL-OFC-2 Km, 100Base VG Any LAN-OFC, 802.3 (Cisco does not support it)

100BaseT- CSMA/CD, 802.3u, Fast Enet,

DOD Model : Proc / Appl : Telnet, FTP, LPD SNMP/ FTP, SMTP, NFS, X window, Host-Host : TCP,UDP,

Internet : ICMP, BootP, ARP, RARP/IP, Net Acc : Ether Net, Fast Enet, Token Ring, FDDI.

Tcp/udp: port Nos. 0-255:used for public appl, 255-1023: for comp to use their appl; >1023 for upper layers sessions with other Hosts. Tcp : virtual ckt, conn oriented, sequenced, ackd, reliable, high o/h, Udp: unsequenced, unreliable, connless, low o/h. ftp>tcp21, telnet>tcp23, smtp>tcp25, tftp>udp69, snmp>udp161, tcp>ip6, udp>ip17

Data Flow : User info is converted to Data(7,6,5), Data converted to Segments(4), Segments converted to Packets or datagrams(3), Packets and datagrams are converted to frames(2), Frames are converted to bits(1).

ICMP Inet Contr Mess Proto: Alerts routers if : Destn unreach, Buffer full, Hops-demise, ping uses ICMP+IP,

sends redirects back to origi router. SNMP: Simple Net Mngmt Proto- used to manage & Monitor Net,

RARP server- gives IP add against MAC add to diskless comp, BootP- gives IP add & boots diskless comp/w stns.

ARP- layer3 proto, Source & Destn H/w add keeps changing, but IP add remains same as pkt travels thro?routers.

LAN Segmentation: breaking up the collision domains by decreasing the number of workstations per segment.

Full Duplex Ethernet : needs full duplex NIC cards, Loop back and collision disabled, 2 x 10/100 MB paths, software driver supporting two simultaneous data paths, Adherence to Enet Stds.

Fast Ethernet (100MB)- provides 10 times the bandwidth of older 10bastT Ethernet. Must have Cat5 cable, no longer than 100 meters, and Fast Ethernet NIC’s and Hubs/Switches.

Gateway?/b>used for comm between diff NOS Eg. NT & IBM SNA,takes the pkt strips off the old protocol and repackages for the receiving network- proto translation (Trans, sessio, prestn, appli).

Router-Filters by both HW add & IP add. strip off data link sourc & dest add & recreates it. Provides flow control, manageability, Explicit pkt life time control, more functionality, multi paths, segments net, links unlike phys media, stops broadcasts, no un routable Net protos , Brouter- will act as router and bridge based on protocols. (DLL, Network).

Bridge-Segs net, filters traff by MAC add, regenerates signal at pkt level, reliability, availability, scalability, manageability, latency, pass broadcasts, no unlike med (DLL,mac sub). Switch-Duplex, filters trafiic on MAC add, pass broadcasts, (DLL) Repeater- regenerates signals for tx, pass broadcasts, no unlike phys media. (Physical).

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