What is CCNP Routing

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Routing

  • CCNP Routing – Forwarding of packets from one network to another network choosing the best path from the routing table.
  • Routing makes possible for two or more different networks to communicate with each other.
  • Routing table consists of only the best routes for every destination.

Types of Routing?

  • Static Routing

    • The Administrator configures it manually.
    • Mandatory need for the Destination Network ID
    • Used for Small organizations
    • Administrative distance for Static Route is 0 or 1.
    • Advantages of static routing
      • There is no overhead on the router CPU
      • There is no bandwidth usage between routers
      • It adds security because the administrator can choose to allow routing access to certain networks only
    • Disadvantages of static routing
      • Used for a small network. (It’s not feasible in large networks)
      • Each and every network has to be manually configured
      • The administrator must really understand the internetwork and how each router is connected in order to configure routes correctly.
      • Any changes in the internetwork have to be updated in all routers
  • Default Routing

    • The default route is used when the destination is unknown (Internet)
    • Also can be used at end locations where there is only one exit path for any destination
    • Last preferred route in the routing table
    • Default routes help in reducing the size of your routing table.
    • If the routers do not found an entry for the destination network in a routing table, the router will forward the packet to its default route.
  • Dynamic Routing

    • Advantages of dynamic over static

      • There is no need to know the destination networks.
      • Need to advertise the directly connected networks.
      • Updates the topology changes dynamically.
      • Administrative work is reduced
      • Used for large organizations.
      • Neighbor routers exchange routing information and build the routing table automatically.
      • This is easier than using static or default routing
    • Types of Dynamic Routing Protocols
      • Distance Vector Protocol
      • Link State Protocol
      • Hybrid Protocol (Advanced Distance Vector Protocol)
Distance Vector Protocol
Link State Protocol
Hybrid Protocol
Works with Bellman-Ford algorithm Works with Dijkstra algorithm Works with a DUAL algorithm
Periodic updates Incremental updates Incremental updates
Classful routing protocols Classless routing protocol Classless routing protocol
Full Routing tables are exchanged Missing routes are exchanged Missing routes are exchanged
Updates are through broadcast Updates are through multicast Updates are through multicast
E.g., RIPv1, RIPv2, IGRP E.g., OSPF, IS-IS E.g., EIGRP
Link state updates Advance Distance Vector Protocol
  • Classful Protocols
    • Classful routing protocol does not carry the subnet mask information along with updates
    • This means all devices in the network must use the same subnet mask
    • E.g., RIPv1, IGRP
    • Classless Protocols
      • Classful routing protocol carries the subnet mask information along with updates
      • This is the reason they support sub-networks & default networks
      • E.g., RIPv2, EIGRP, OSPF, and IS-IS
    • Administrative Distance
      • It is the trustworthiness of the information received by the router.
      • The Number is between 0 and 255
      • Least value is more preferred.
      • Default administrative distances are as follows:
        • Directly Connected = 0
        • Static Route = 1
        • IGRP = 100
        • OSPF = 110
        • RIP = 120
        • EIGRP = 90/170
        • IS-IS   = 115

Autonomous System Number

  • An Autonomous System is a collection of networks under a common administrative domain
  • A unique number identifying the Routing domain of the routers.
  • Ranges from 1- 65535
    • Public from 1 – 64512
    • Private from 64513 – 65535
  • Private AS is used within the same service providers
  • Public AS is used in between multiple service providers

Routing Protocol Classification

IGP
EGP
Interior Gateway Protocol Exterior Gateway Protocol
Routing protocols used within the same autonomous system number The routing protocol used between different autonomous systems
All routers will be routed within the same Autonomous boundary Routers in different AS need an EGP
E.g., RIP, IGRP, EIGRP, OSPF, IS-IS E.g., BGP – Border Gateway Protocol
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OSI Reference Model

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