Hubs- one tx, all other rx, simplex, no addressing(Physical).Multiplexer- for multiplexing links.(Physical)

Repeater reduces dist for 100BaseFx due to delays, but extends 100BaseTx dist. Class1:Translational rptr supports both 100baseX and 100baset4 signalling. Delay=140 bit times, Class 2:Transparent rptr only supports either 100baseX or 100baseT4, not both at same time.delay=92 bit times. FastHub300: Rptr compatible with 802.3u for fast Enet.

LAN Switching : Uses dest MAC add to forwd pkts. same as multi port Bridge. Multi simultaneous convs, high speed data exges, low latency & high frame fowd rates, full duplex, media rate adaption (10/100). Port Switching: port assigned to a phys net by software. Frame Switching: increases b/w on the net. Allows multi trans in parallel. used in Cisco Cata switch. Cell Switching: ATM. Uses small fixed length cells that are switched on the net. Used in Cisco light stream switches.

Router Switching : Store & Forward: copies entire frame in to buffers and checks CRC. Forwards 64-1518 Bytes only. latency high depends on Frame Length. used in cat 05000/5505 series. Cut-through (Real Time): copies only dest add (6B) in to buffers. some switches automly uses both modes, Low latency, 10/100mb full duplex Fragment Free: modified cut thro. Waits for collision window (first 64 B). Better error checking, no latency.

Spanning-Tree Protocol (STP) IEEE 802.1d- to prevent routing loops. STA (Spanning-Tree Algorithm) is impled by STP to calculate a loop-free net topology. In Cat 5000 based nets Bridge proto data units (BPDU) are sent & recd by all switch in regular intervals & processed to determine spanning-tree topology.

Virtual LAN’s-have diff ports of a switch be parts of diff sub nets. can be by location, function, grp & dept. Simplify moves, adds, changes. less admn costs, better control of broadcasts, tighten net security, distribute load, Relocate server into secured locations. Frame tagging: A user defined ID for each frame, places a unique user defined ID in the header of each frame used within switch fabric itself. Used in Cat 3000 & 5000 series. Developed for multi VLAN, Inter switch Commn, needs processor & admn load.

IP Address Classes:

(2)192-2-4194302-16382-62 Class A Net.Node.Node.Node 0 1-127 127 net 16777214 nodes

(3)224-6-2097150-8190-30 Class B Net.Net.Node.Node 10 128-191 16384 net 65534 nodes

(4)240-14-1048574-4094-14 Class C Net.Net.Net.Node 110 192-223 2097152 net 254 nodes

(5)248-30-524286-2046-6 (net/node all 0-this net/node, all 1-all net/node) (127-loopback add )

(6)252-62-262142-1022-2 (entire IP all 0-cisco default route, all 1-broadcast to all nodes)

(7)254-126-131070-510-na Max # of Subnets: 2(masked bits)-2, Max # of Hosts / subnet : 2(unmasked bits)-2

(8)255-254-65534-254-na Class D-224-239-Multicasts, Class E- 240-255-Future.

Directed / only subnet broadcast add- 172.16.3.255, Flooding / total Network broadcast add- 172.16.255.255

Cisco Routers :
2500 : Cons port- async serial port RJ45 60 Pins, Aux port- Modem RJ45,Telnet port - Ethernet 0, (S0,S1-serial port), External ports - TFTP server, Virtual Term, Net Mngmt Stns. ROM-holds Bootstrap Startup programs, OS software, POST. Flash-EEPROM-holds cisco IOS image and Microcode, RAM-holds running OS, running config, provides caching & pkt filtering. NVRAM-Stores startup config, config mem: executes NVRAM commands, copies start to Run,

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