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R&S C7: Routing Dynamically (7.6 Summary ((cisco routers use the…

- - - - used since late 1980
      - newer version support ipv6
      - dynamic protocols
        
        Interior Gateway Protocols
        
        IGPs
        
        inside our network
        
        Distance Vector Routing Protocols
        
        learn routes by neighbour,
        they trust neighbour
        
        learn route
        
        how far it is
        
        and what direction
        
        RIP
        
        legacy protocol
        
        not supported
        
        RIPv2
        
        IGRP
        
        legacy protocol
        
        not supported
        
        EIGRP
        
        Link State Routing Protocols
        
        want to build map of whole topology
        before making decission to send the packet
        
        OSPF
        
        IS-IS
        
        Exterior Gateway Protocols
        
        EGPs
        
        communicate with someone on another network
        
        Path-Vector Routing Protocol
        
        BGP
    - - routing protocols are used to facilitate the exchange of routing information between routers
      - purpose
        
        discovery of remote networks
        
        maintaining up-to-date routing information
        
        choose best path to destination network
        
        ability to find new best path
        if old one is no longer available
      - main components
        
        Data structures
        
        routing protocols typically use tables or database for its operations. Kept in RAM
        
        routing protocol messages
        
        routing protocols use various types of messages to discover neighboring routers, exchange routing information, and other tasks to learn and maintain accurate information
        
        algorithm
        
        routing protocols use algorithms for facilitating routing information for the best path determination
    - - advantages
        
        auto share info about remote networks
        
        determine best path and add info to routing tables
        
        in comparison with static routing
        = require less administrative overhead
        
        help network admin manage time-consuming process of configuring and maintaining static routes
      - disadvantages
        
        part of router resources dedicated for protocol operation,
        including CPU time and network link bandwidth
        
        when static routing is more appropriate
  - - - disadvantages static routing
        
        only simple topologies
        
        default static route
        
        manual intervention is required to re-route traffic
      - advantages static routing
        
        secure (no advertisements sent )
        
        route destination is always the same
        
        extra CPU and
        RAM not required
        
        no routing algorithm/
        update machanism required
        
        easy to implement in a small network
      - advantage dynamic routing
        
        suitable in all topologies where multiple routers are required
        
        independent of network size
        
        automatically adapts topology to reroute traffic if possible
      - disadvantages dynamic routing
        
        more complex to implement
        
        less secure
        
        additional config settings are required too secure
        
        route depends on current topology
        
        require additional CPU, link bandwidth
  - - - operations
        
        router sends/receives routing messages on its interface
        
        router shares routing messages
        and routing information
        THEY NEED TO USE SAME PROTOCOL
        
        they need to use the same protocol
        
        routers exchange routing information to learn about remote networks
        
        when router detects a topology change the routing protocol can advertise this change to other networks
    - - R1 doesn't know about network between R2 and R3
    - - send update from opposite site of the network to the other side of the network
      - on update : in the network table they add the network interfaceon which they received the update packet
    - - network not converged, because router 2 knows how to get to R1 and R3, but R1 can't reach 10.4.0.0
      - newly added info from R2 will send it towards R1 and R3
    - - network converged when all routers have complete and accurate information about the entire network
      - convergence time is the time it takes routers to share information, calculate best paths, and update their routing tables
      - network not completely operable until the network has converged
      - convergence properties include speed of propagation of routing information and calculation of optimal paths
        The speed of propagation refers to the amount of time it takes for routers within the network to forward routing information
      - RIP old protocol is slower to converge
      - EIGRP and OSPF modern protocols, converge more quickly
  - - - Purpose
        
        Exterior Gateway Protocols (EGP)
        
        Operation
        
        path-vector routing protocol
        
        behaviour
        
        classless
        
        1 more item...
        
        Interior Gateway protcols (IGP)
        
        operation
        
        distance vector routing protocols
        
        behaviour
        
        classful
        
        2 more items...
        
        classless
        
        2 more items...
        
        RIPv1 and
        IGRP are legacy
        
        link-state routing protocols
        
        behaviour
        
        classless
        
        2 more items...
        
        link-state routing protocols
        are classless by nature
      - Behaviour
    - - IGP
        
        used by organizations and
        within service provider's network
      - EGP
        
        used for routing between AS
        
        official routing protocol used by the internet
      - only one
        connection
        
        use default static route
      - EGPs between IGPs , EGP is always BGP (or Default static route) - IGP can be EIGRP , IS-IS, OSPF
    - - Distance vector
        
        routes advertised as vectors of distance and direction
        
        distance defined as
        
        metric
        
        hop count
        
        direction defined as
        
        nexthop router
        
        exit interface
      - use Bellman-Ford algorithmn for best-path route determination
      - distance vector protocols use rotuers as sign posts along the path to the final destination
    - - a link-state routing protocol is like having a complete map of the network topology. The sign posts along the way from source to destination are not necessary, because all link-state routers using an identical map of the network. A link-state router uses the link-state information to create a topologt map and to select the best path to ll destination networks in the topology
      - OSPF
      - IS-IS
    - - do not send subnet mask information in their routing updates
      - only RIPv1 and IGRP
      - when network addresses were allocated based on classes (A,b or C)
      - cannot provide variable length subnet masks (VLSMs)
        and classless interdomain routing (CIDR)
      - create problems in discontiguous networks
        
        discontiguous : niet aangrenzend , geen gemeenschappelijke grens hebbend
    - - include subnet mask information in routing tables
      - RIPv2, EIGRP, OSPF, IS-iS
      - support VLSM and CIDR
      - IPv6 routing protocols
    - - Distance vector | Link State
        
        RIPv1 || RIPv2 || IGRP ||||||||| EIGRP || OSPF || IS-IS **
        
        slow || slow || slow ||||||||| fast || fast || fast >>> Speed of convergence
        
        small || small || small ||||||||| large || large || large >>> scalability
        
        no || yes || no ||||||||| yes || yes || yes >>> use of VLSM
        
        low || low || low ||||||||| medium || high || high >>> resource usage
        
        simple || simple || simple ||||||||| complex || complex || complex >>> Implementation & Maintenance
    - - measurable value that is assigned by the routing protocol to different routes based on the usefulness of that route
      - used to determine overall cost of path from source to destination
      - routing protocols determine best path based on the route with lowest cost
      - routing protocol --- default metric --- description
        
        RIP --- Hop Count--- simple metric counts number of routers a packet traverses
        EIGRP -- Bandwidth and Delay --- highest overall bandwidth, delay considers time a packet takes to traverse a path
        OSPF --- Cost --- a value based on the cumulative link bandwidths
        
        traverse : move back
        and forth or sideways.
    - - link state protocols do not
        have problems with loops
        
        has the whole map
- - - - share updates between neighbors
      - not aware of network topology
      - update consume bandwidth and CPU
      - RIPv2 and EIGRP are multicast addresses
      - EIGRP will only send an update when topology has changed
    - - RIP
        
        Bellman-Ford algorithm as routing algoritm
      - IGRP AND EIGRP
        
        use Diffusing Update Algorithm (DUAL)
        routing algorithm developed by Cisco
  - - - RIP
      - broadcast every 30 seconds
      - RIPng based on RIPv2 with a 15 hop limitation
      - administrative distance of 120
      - Characteristics and features
        
        RIPv1 ||||||||| RIPv2
        
        both use hop count as a simple metrix - max hop 15 >>> metrix
        
        255.255.255.255 || 224.0.0.9 >>> forward updates to address
        
        No || yes >>> supports VLSM
        
        No || Yes >>> supports CIDR
        
        No || Yes >>> Supports Summarization
        
        No || Yes >>> Secure
    - - EIGRP
      - only updates when needed
      - uses hello mechanisl
        (keepalives)
      - maintian topology table
      - supports rapid convergence
      - is a multiple network layer
        protocol support
      - 224.0.0.10 (how to remember: A hex is 10, A = advanced)
      - Characteristics and features
        
        IGRP ||||||||| EIGRP
        
        both use composite metric consist of bandwidth and delay >>> metric
        
        255.255.255.255 || 224.0.0.10 >>> forward updates to address
        
        No || yes >>> supports VLSM
        
        No || Yes >>> supports CIDR
        
        No || Yes >>> Supports Summarization
        
        No || Yes >>> Secure
- - - - conf f> router rip > network 192.168.1.0 > network 192.168.2.0
      - enter each directly connected network
    - - show ip protocols
      - show ip route | begin gateway
    - - router rip > version 2
      - show ip protocols | section Default
      - ipv version 2 > no version > default setting
    - - no auto-summary
    - - sending out unneeded
        updates on a LAN
        
        waste bandwidth
        
        waste resources
        
        security risk
      - passive interface :
        not sending update
      - it is still advertised
      - router rip > passive-interface g0/0 > end
    - - commonto configure default static route on an edge router and then propagating the defualt route throughout the routing domain using the routing protocol
      - edge routers must be
        configured with default static route
        
        ip route 0.0.0.0 0.0.0.0 exit-intf next-hop-ip
      - propagated to other routers via RIP using:
        
        default-information originate
  - - - no network command with router rip
      - interface configuration command
        
        ipv6 rip domain-name enable
      - ipv6 unicast-routing > interface gigabitethernet 0/0 ipv6 rip RIP-AS enable > exit > interface serial 0/0/0 >ipv6 rip RIP-AS enable
    - - it does include itself as a HOP
- - - - l1. earns about own links and own directly connected networks
      - each router is responsible for meeting its neighbors on directly connected networks
      - each router builds link-state packet (LSP) containing the state of each directly connected link
      - each rooter floods the LSP to
        all neighbors , who then store
        all LSPs received in a database
      - 5 each router uses database to construct a complete map of the topology and computes the best path to each destination network
    - - link-state routing process is that each router is responsible for meeting its neighbors on directly connected networks
    - - 1.each router learns about each of its own directly connected networks
      - 2.each router is responsible for "saying hello" to its neighbors on directly connected networks
      - each router builds a Link State Packet (LSP) containing the state of each directly connected link
      - 4.each router floods the LSP to all neighbors who tehn store all LSP's received in a database
      - 5.each router uses the database to construct a complete map of topology and computers the best path to each destination networks
    - - each routers builds a link-state packet (LSP) containing the state of each directly connected link
    - - each rooter floods the LSP to all neighbors , who then store all LSPs received in a database
    - - each router uses the database to construct a complete map of the topology and computes the best path to each destination network
    - - identify directly connected networks
    - - populate the routing table
    - - link-state routing process is that each router learns about its own links and its own directly connected networks
  - - - advantage
        
        each router builds its own topological map of the network to determine the shortest path
        
        immediate flooding of LSPs achieves faster convergence
        
        LSPs are sent only when there is a change in the topology and contain only the information regarding that change
        
        hierarchical design used when implementing multiple areas
      - disadvantage
        
        maintaining a link-state database and SPF tree requires additional memory
        
        calculating the SPF algorithm also requires additional CPU processing
        
        Bandwidth can be adversely affected by link-state packet flooding
    - - Open Shortest Path First (OSPF)
        
        OSPFv2
        
        OSPF for IPv4
        
        OSPFv3
        
        OSPF for IPv6
      - (IS-IS )
        
        designed by International Organization for Standardization (ISO)
- - - - S
        
        static route
      - D
        
        EIGRP routing protocol
      - O
        
        OSPF routing protocol
      - R
        
        RIP routing protoclol
      - C 172.16.1.0/24 is directly connected, GigabitEthernet0/0
        
        C = route source
        
        172.16.1.0/24 is directly connected = destination network
        
        Gigabitethernet0/0 = outgoing interface
    - - contains either
        
        next-hop IP address
        or exit interface
        
        can be directly connected , dynamic
        , static , and link local routes are ultimate routes
    - - with subbnet mask equal to or less than
        the classful mask of the network address
      - can function as
        
        default route
        
        default route is a static route
        with the address 0.0.0.0/0
        
        supernet route
        
        route with network address with a
        mask less than the classful mask
        
        network route
        
        has a subnet mask equal to that of the classful mask
    - - is level 1 route that has
        been subnetted
      - created automatically any time a subnet is
        added to the routing table
      - can never be
        an ultimate route
    - - is a route that is a subnet of
        a classful network address
  - - - if the best match is a level 1 ultimate route,
        this route is used to forward the packet
      - best match is level 1 parent route
        , proceed to the next step
      - router examines child routes (subnet routes) of the
        parent route for a best match
      - is there is a match with a level 2 child route,
        subnet is used to forward the packet
      - if there is not a match with any of
        the level 2 child routes, proceed to the next step
      - 6 routes continues searching level 1 supernet routes in the routing table for a match, including the default route, if there is one
      - if there is now a lesser match with a level 1 supernet or default routes, the router uses that route to forward the packet
      - if there is not a match with any route in the routing table, the router drops the packet
  - - - components of the IPv6 routing table are very similar to the IPv4 routing table (directly connected interfaces, static routes, and dynamically learned routes).
      - IPv6 classless by design, all routes are effectively level 1 ultimate routes.
        There is no level 1 parent of level 2 child routes