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R&S C6 : Static Routing (6.6 Summary ((a static route is only entered…

- - - - Manually
        
        manually entered into the
        route table using static routes
      - Dynamically
        
        automatically learned using
        a dynamic routing protocol
    - - static advantages over dynamic
        
        security +
        
        (static route is not advertised over network)
        
        less bandwidth
        
        (no CPU cycles)
        
        path is known
      - disadvantages
        
        configuration
        
        more vulnerable to erorrs in large networks
        
        admin needed for changes in network
        
        bad at scaling
        
        complete knowledge of the whole network for
        proper implementation
    - - small networks
      - routing to/from stub networks
        
        stub network = accessed by
        a single route
      - using single default route to
        represent a path to any network
  - - - use static routes to
        
        connect to a specific network
        
        connect a stub router
        
        summarize routing table entries
        
        create a backup route
    - - connect to specific route network
    - - matches all packets
      - identifies gateway IP address
        to which the router sends all IP packets
        that it does not have learned or static route
      - default static routes are used:
        
        no other routes in the routing table match the packet destination IP address
        
        router has only one other router
        to which it is connected
    - - multiple static routes summarized
        into single static route
        
        destination networks next to each other
        
        multiple static routes use
        the same exit interface /
        next-hop IP address
    - - used to provide backup path
        to primary path/dynamic path
        
        configured with higher
        administrative distance
- - - - network-address
        
        destination network address of
        the remote network to be added to
        the routing table
      - subnet-mask
        
        subnet mask of the remote network to be added to the routing table
      - ip-address
        
        IP address of the connecting router
        to use to forward the packet to the
        remote destination network
      - exit-intf
        
        outgoing interface to use to forward the packet
        to the next hop
    - - Next-hop route
        
        only the next-hop
        IP address is specified
      - Directly connected static route
        
        only the router exit
        interface is specified
      - Fully specified static route
        
        next-hop IP address and
        exit interface are specified
    - - looks for a match in the routing table and finds that it has to forward the packets to the next-hop IPv4 address
      - router1 must determine how to reach 172.16.2.2
        searches a second time for a 172.16.2.2 match
    - - when CEF is not enabled , a directly attached statis route avoids the recursive lookup problem on point-to-point networks.
        It allows the routing table to resolve the exit interface in a single search, instead of two searches
      - typically used with point-to-point serial interfaces
    - - both the output interface and the next-hop IP address are specified
      - another type of static route that is used in older IOSs, prior to CEF
      - this form of static route is used when the output interface is a multi-access interface and it is necessary to explicitly identify the next hop
      - next hop must be directly connected to the specified exit interface
    - - show ip route
      - show ip route static
      - show ip route network
  - - - ip route 0.0.0.0 0.0.0.0 { ip-address | exit-intf }
    - - ip route 0.0.0.0 0.0.0.0 172.16.2.2
    - - show ip route static
        
        L - local
        
        C - connected
        
        S - Static
        
        R - RIP
        
        M - mobile
        
        B -BGP
        
        D - EIGRP
      - Gateway of last resort is 172.16.2.2 to network 0.0.0.0
      - S* 0.0.0.0/0 [1/0] via 172.16.2.2
  - - - almost identical to IPv4
      - can be implemented as
        
        Standard IPv6 static route
        
        Default IPv6 static route
        
        Summart IPv6 Static route
        
        Floating IPv6 static troute
    - - the next hop can be identified by an IPv6 address, exit interface, or both. How the destination is specified creates one of three route types:
        
        Next-hop IPv6 route - only the next-hop IPv6 address is specified
        
        Directly connected static IPv6 route - Only the router exit interface is specified
        
        Fully specified static IPv6 route The next-hop IPv6 address and exit interface are specified
    - - ipv6 route 2001:DB8:ACAD:2::/64 2001:DB8:ACAD:4::2
    - - ipv6 route 2001:DB8:ACAD:2::/64 s0/0//0
    - - ipv6 route 2001:DB8:ACAD:2::/64 fe80::2
      - ipv6 route 2001:DB8:ACAD:2::/64 s0/0/0 fe80::2
    - - show ipv6 route
      - show ipv6 route static
      - show ipv6 route
  - - - ipv6 route ::/0 { ipv6-address | exit-intf}
    - - ipv6 route ::/0 2001:DB8:ACAD:4::2
    - - show ipv6 route static
        
        S ::/0 [1/0] via 2001:DB8:ACAD:4::2
- - - - Class
        
        High Order Bits
        
        Start
        
        End
      - Class A
        
        0xxxxxxxx
        
        0.0.0.0
        
        127.255.255.255
      - Class B
        
        10xxxxxx
        
        128.0.0.0
        
        191.255.255.255
      - Class C
        
        110xxxxx
        
        192.0.0.0
        
        223.255.255.255
      - Multicast
        
        1110xxxx
        
        224.0.0.0
        
        239.255.255.255
      - Reserved
        
        1111xxxx
        
        240.0.0.0
        
        255.255.255.255
    - - Class A
        
        255.0.0.0
      - Class B
        
        255.255.0.0
      - Class C
        
        255.255.255.0
      - 255 = Network
      - 0 = host
    - - Class A (1-126)
        
        amount of possible networks: 126
        
        amount of Hosts/Net : 16,777,214
        
        Max amount of Hosts 2,113,928,964
      - Class B (128 - 191)
        
        amount of possible networks : 16,384
        
        amount of hosts/net 65,634
        
        max amount of hosts: 1,073,709,056
      - Class C (192 - 223)
        
        amount of possible networks 2,097,152
        
        amount of hosts/net 254
        
        max amount hosts 532,676,608
  - - - efficient
      - only used what is needed
    - - R1(config)# no ip route 172.16.0.0 255.255.0.0 s0/0/0
        ...
        ...
        ...
        ip route 172.16.0.0 255.248.0.0 s0/0/0
  - - - network portion and host portion
        
        in host protion there is a subnet portion
        
        subnet portion is 2^3 = 8
        
        new host portion is 2^5 -2 = 30 hosts per subnet
      - 11000000.10101000.00010100 . 000 00000
        
        192.168.20.0/27
    - - VLSM allows the use of different
        masks for each subnet:
        
        VLSM is simply subnetting a subnet. VLSM can be thought of as sub-subnetting
        
        Individuel host addresses are assigned from the addresses of "sub-subnets"
        
        after a network address is subnetted, those subnets can be further subnetted
- - - - also known as route aggregation, is the process of advertising a contiguous set of addresses as a single address with less-specific short subnet mask:
        
        CIDR is a form of route summarization and is synonymous with the term supernetting
        
        CIDR ignores the limitation of lcassful boundaries, and allows summarization with masks that are smaller than that of the default classful mask
        
        this type of summarization helps reduce the number of entries in routing updates and lowers the number of entries in local routing tables
    - - 2.calculate the number of far-left matching bits to determine the mask
      - copy the matching bits and add zero bits to determine the network address
        
        172.20.0.0
  - - - same as IPv4 with extra steps
        
        if destination networks are contiguous and can be summarrized into a single network address
        
        if multiple static routes all use the same exit interface or next-hop IPvv6 address
    - - steps
        
        list the network addresses (prefixes) and identify the part where the addresses differ
        
        expand the IPv6 if it is abbreviated
        
        convert the differing section from hex to binary
        
        count the number of far left matching bits to determine the prefix-length for the summary route
        
        copy the matching bits and then add zero bits to determine the summarized network address (prefix)
        
        convert binary section back to hex
        
        append the prefix of the summary route (result of step4)
  - - - are static routes that have an administrative distance greater than the administrative distance of another static route or dynamic route
        
        the administrative distance of a static route can be increasted to make the route less desirable than that of another static route or a route learned through a dynamic routing protocol
        
        in this way, the static route "floats" and is not used when the route with the better administrative distance is active
        
        if preferred route i slost, the floating static route can take over, and traffic can be sent through this alternate route
    - - ip route 0.0.0.0 0.0.0.0 172.16.2.2
    - - show ip route
        
        verify that the routing table is using the default static route
      - traceroute
        
        follow the traffic flow out the primary route
      - disconnect the primary link or shutdown the primary exit interface
      - show ip route
        
        verify that the routing table is using the floating static route
      - traceroute
        
        follow the traffic out the backup route
- - - - ping - traceroute - show ip route - show ip interface brief - show cdp neighbors detail
    - - use ping to confirm destination can't be reached
      - traceroute reveals closest router (/hop) that fails to respond as pxected, In this case, the router would then send an Internet Control Message Protocol (ICMP)
      - next step is to investigate the routing table.
        Look for missing or misconfigured routes
      - incorrect static routes are common cause of routing problems
      - PART2
        
        ping 192.168.2.1 source g0/0
      - PART 3
        
        when TTL is zero (Time to Live)
        router would send an Internet Control Message Protocol (ICMP) destination unreachable message to R1