CCNA 3 - Capitulo 1.2

CCNA 3 - Capitulo 1.2

1. SINGLE ARE OSPFv2 CONCEPTS

   • OSPF FEATURES AND CHARACTERISTICS
     • LINK STATE OPERATION
       • 1.ESTABLISH NEIGHBOR ADJACENCIES
         • OSPF ENABLED ROUTERS MUST RECOGNIZE EACH OTHER ROUTERS BEFORE CAN SHARE INFORMATION
         • 1. ALL OSPF ENABLED ROUTERS SENDS HELLO PACKETS
           • TO DETERMINE IF NEIGHBORS ARE PRESET ON THOSE LINKS
         • 2. IF A NEIGHBOR IS PRESENT
           • ROUTER ATTEMPS ESTABLISH ADJACENCY
       • 2.EXCHANGE LINK STATE ADVERTISEMENTS
         • AFTER ADJACENCIES ARE ESTABLISHED
           • ROUTERS EXCHANGE
             • LINK STATE ADVERTISEMENTS (LSAs)
               • WHATS LSAs CONTAIS ?
                 • STATE AND COST EACH DIRETLY CONNECTED LINK
               • HOW DOES IT WORK?
                 • 1.ROUTERS FLOOD LSA TO ADJACENT NEIGHBORS
                 • 2. ADJACENT NEIGHBORS RECEIVING THE SLA IMMEDIATELY FLOOD THE LSA
                   • TO OTHER DIRECLY CONNECTED NEIGHBORS , UNTIL ALL ROUTERS IN THE ARE HAVE ALL LSAs
       • 3.BUILD THE LINK STATE DATE BASE
         • AFTER LSAs ARE RECEIVED , OSPF ENABLED ROUTERS BUILD THE TOPOLOGY TABLE (LSDB) BASED ON THE RECEIVED LSAs
         • THIS DATABASE CONTAINS
           • INFORMATION ABOUT THE TOPOLOGY OF THE AREA
       • 4.EXECUTE SPF ALGORITHM
         • NOW ROUTERS EXECUTE SPF ALGORITHM
           • SPF CREATES THE SPF TREE
       • 5) CHOOSE THE BEST ROUTE
         • AFTER THE SPF TREE IS BUILT , THE BEST PATHS TO EACH NETWORK ARE OFFERED TO THE IP ROUTING TABLE
         • UNLESS THERE IS A ROUTE SOURCE TO THE SAME NETWORK WITH A LOWER ADMINISTRATIVE DISTANCE SUCH STATIC ROUTE
       • WHATS IS ?
         • GENERIC PROCESS TO REACH A STATE OF CONVERGENCE TO MAINTAIN ROUTING INFORMATION
     • SINGLE AREA & MULTIAREA OSPF
       • SINGLE AREA
         • ALL ROUTERS ARE IN ONE AREA
         • BEST PRACTICE IS TO USE AREA 0
       • MULTIAREA OSPF
         • TO MAKE OSPF MORE EFFICIENT AND SCALABLE SUPPORTS
           • HIERARCHICAL USING AREAS CONCEPTS
         • WHATS IS PURPOSE ?
           • HIERARCHICAL ROUTING DESIGN
           • DIVIDE ONE LARGE ROUTING DOMAIN INTO
             • SMALLER AREAS
           • IMPROVE SCALABILITY AND PERFORMANCE
         • ATTENTION
           • ALL AREAS MUST CONNECTED
             • BACKBONE AREA (AREA 0)
           • ROUTERS INTERCONNECTING ARE REFERRED
             • AREA BORDER ROUTERS (ABRs)
         • HOW IT WORKS
           • AREAS ARE CONNECTED THROUGH AREA 0 (BACKBONE)
           • INTER-AREA ROUTING HAPPENS VIA ABR
         • AREAS ARE CREATED
           • EACH AREA HAS ITS OWN LSDB
           • SPF CALCULATION HAPPENS PER AREA
         • TOPOLOGY CHANGE BEHAVIOR
           • CHANGE INSIDE AN AREA
             • ROUTERS DETECT LSA
             • RUN SPF ALGORITHM
             • BUILD NEW SPF TREE
             • UPDATE ROUTING TABLE
           • CHANGE OUTSIDE THE AREA
             • ROUTERS RECEIVE SUMMARIZED LSA
             • DO NOT RUN SPF
             • ONLY UPDATE ROUTING TABLE
           • IMPACT IS LOCALIZED
         • WHY IT IMPROVES PERFORMANCE
           • SMALLER LSDB PER AREA
           • FEWER SPF RECALCULATIONS
           • REDUCED CPU USAGE
           • REDUCED MEMORY USAGE
           • LIMITED LSA FLOODING
       • WHATS IS OSPF AREA ?
         • GROUP OF ROUTERS TO SHARE THE SAME LINK STATE INFORMATION IN THEIR LSDBs

2. SINGLE ARE OSPFv3 CONCEPTS

   • FEATURES AND CHARACTERISTICS
     • OSPFv3
       • IS EQUIVALENT OSPFv2 FOR EXCHANGING IPV6 PREFIX
       • FAMILY FEATURES INCLUDES SUPPORT
         • BOTH IPV4 AND IPV6
       • SAME FUNCTIONALITY AS OSPFv2, BUT USES IPV6 AS THE NETWORK LAYER TRANPORT
       • ALSO USES THE SPF ALGORITHM
       • HAS SEPARATE PROCESSES FROM ITS IPV4 COUNTERPART , RUN INDEPENDENTLY
         • OSPFv2 AND OSPFv3 EACH SEPARETE ADJASCENCY TABLES
       • COMAMND AS CONFIGURATION ARE SIMULAR BOTH OSPFv2 AND OSPFv3