CCNA - Capitulo 7.3

CCNA - Capitulo 7.3

1. ETHERNET SWITCHING

   • SWITCH SPEEDS AND FORWARDING METHODS
     • MEMORY BUFFERING ON SWITCHES
       • PORT BASED
         • FRAME STORED IN
           • QUEUES
             • LINKED TO SPECIFIC INCOMING AND OUTGOING PORTS.
               • INCOMING AND OUTGOING PORTS
         • A FRAME IS TRANSMITTED QUEUE
           • ONLY
             • WHEN ALL THE FRAMES AHEAD IN THE QUEUE HAVE BEEN SUCCESSFULLY TRANSMITTED.
         • SINGLE FRAME
           • DELAY THE TRANSMISSION
             • OCCURS EVEN IF THE OTHER FRAMES COULD BE TRANSMITTED TO OPEN DESTINATION PORTS.
       • SHARED MEMORY
         • DEPOSITS ALL FRAME
           • COMMON MEMORY BUFFER SHARED
             • BY ALL SWITCH PORTS AND THE AMOUNT OF BUFFER MEMORY
         • DYNAMICALLY ALLOCATED.
           • BY A PORT
         • DIFFERENCE FROM PORT BASED ?
           • PACKET TO BE RECEIVED ON ONE PORT AND THEN TRANSMITTED ON ANOTHER PORT
         • STORE LARGER FRAMES STORED LARGER LARGER FRAME
           • WITH FEWER DROPPED FRAMES
     • FORWARDING METHODS CISCO SWITCHES
       • AUTO MDIX
         • SWITCH AUTOMATICALLY DETECTS THE TYPE OF CABLE ATTACHED TO THE PORT
           • AND CONFIGURES THE INTERFACES ACCORDINGLY
         • WHATS IS AUTO MDIX ?
           • COMMAND GLOBAL : AUTO MDIX AUTO
           • WHEN ENABLE , THE SWITCH AUTOMATICALLY DETECTS THE TYPE OF CABLE ATTACHADED TO THE PORT AND CODIURES THE INTERFACE ACORDINGLY
       • 2 - STORAGE AND FORWARD
         • 1) RECEIVES FRAME AND COMPUTES THE CRC
           • ERROR ? DISCARD
             • REDUCES THE AMOUNT OF BADWIDTH CONSUMED BY CORRUPT DATA
           • CRC - MATHEMATICAL FORMULA BASED OF NUMBER BITS
             • 12121209
               • 12121209
         • 2) IF THERE ARE NO ERRORS, AND IT IS IN THE TABLE, IT WILL BE FORWARDED;
         • IS REQUERED FOR QOS
       • 1 - CUT THROUGH
         • FORWARDS THE FRAME BEFORE IT IS ENTIRELY RECEIVED
           • (MINIMUM
             • DESTINATION ADDRESS MAC
         • SWITCH DOES NOT PERFORM ANY ERROR CHECKING ON THE FRAME.
         • 2 VARIANTS
           • FAST FORWARD
             • LOWEST LEVEL OF LATENCY
               • HOW IS LATENCY MEASURED?
                 • FROM BIT RECEIVED TO THE FIRST BIT TRANSMITTED
             • SWITCHING FORWARDS A PACKET AFTER READING
               • THE DESTINATION ADDRESS
             • TIMES WHEN PACKETS ARE RELAYED WITH ERRORS
             • CUT THROUGH OF THE TYPICAL METHOD
           • WITHOUT FRAGMENTS FREE
             • THE FRAME BEFORE FORWARDING.
             • THE SWITCH STORES THE FIRST 64 BYTES BEFORE FORWARDING
               • REASONS STORED FIRST 64 BYTES ?
                 • THAT MOST NETWORK ERROS AND COLISSIONS OCCUR DURNG ALL FIRST 64 BYTES
             • VARIANT OF FAST FORWARIND AND STORED AND FORWARIDING
             • A COMPROMISE BETWEEN THE HIGH INTEGRITY OF STORED AND FORWARDED DATA AND THE LOW LATENCY OF CUT-THROUGH DATA.
         • THE SWITCH LOOKS UP THE DESTINATION MAC ADDRESS IN ITS SWITCH TABLE AND FORWARDING
       • SWITCH SPEEDS
         • BEST SPEED AND DUPLEX SETTING
           • 3 - AUTO NEGOTIATION
             • OPTIONAL FUNCTION FOUNDS ETHERNET NIC END DEVICES
             • TWO DEVICES AUTOMATICALLY NEGOTIATE BEST SPEED AND DUPLEX
             • CISCO SWITCHS AND ETHENET NICS DEFAULT AUTONEGOTIATE SPEED AND DUPLEX
             • GIGABIT OPERATE ONLY FULL DUPLEX
           • 1 - FULL DUPLEX
             • BOTH ENDS OF THE CONNECTION CAN SEND AND RECEIVE SIMULTANEOUSLY.
             • IS CHOSEN IF BOTH DEVICES HAVE THE CAPABILITY ALONG
               • WITH THEIR HIGHEST COMMON BANDWIDTH.
           • 2 - HALD FUPLEX
             • ONLY ONE END OF THE CONNECTION CAN SEND AT A TIME.
           • BANDWITCH - SPEED
           • OBSERVAÇÃO
             • DUPLEX AND BANDWITCH SETTINGS MATCH BETWEEN THE SWITCH PORT AND THE CONNECTED DEVICES , END DEVICES , ROUTER , SERVER , FIREWALL
           • WHAT IS DUPLEX MISMATCH ?
             • OCCURS WHEN ONE PORT ON THE LINK OPERATES AT HALF DUPLEX WHILE THE OTHER PORT OPERATES AT FULL DUPLEX
             • BEST PRACTICES ?
               • BOTH ETHERNET SWITCHES PORTS ARE AS FULL DUPLEX
       • THIS OCCURS WHEN TWO DEVICES ATTEMPT TO TRANSMIT AT THE SAME TIME.
       • SOME SWITCHES CONFIGURED PERFORM CUT THROUGH PER PORT BASIS ULTIL A USER DEFINED ERROR THRESHROLD
         • AND THEY AUTOMATICALLY CHANGE TO STORED AND FORWARDING