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RIPv1 and RIPv2, EIGRP vs OSPF

Introduction:
Administrative distance:
Most routing protocols have metric structures and algorithms that are not compatible with other protocols. In a network with multiple routing protocols, the exchange of route information and the capability to select the best path across the multiple protocols are critical.
Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. Administrative distance defines the reliability of a routing protocol. Each routing protocol is prioritized in order of most to least reliable (believable) with the help of an administrative distance value.
Select the Best PathAdministrative distance is the first criterion that a router uses to determine which routing protocol to use if two protocols provide route information for the same destination. Administrative distance is a measure of the trustworthiness of the source of the routing information. Administrative distance has only local significance, and is not advertised in routing updates.
Note: The smaller the administrative distance value, the more reliable the protocol. For example, if a router receives a route to a certain network from both Open Shortest Path First (OSPF) (default administrative distance - 110) and Interior Gateway Routing Protocol (IGRP) (default administrative distance - 100), the router chooses IGRP because IGRP is more reliable. This means the router adds the IGRP version of the route to the routing table.
If you lose the source of the IGRP-derived information (for example, due to a power shutdown), the software uses the OSPF-derived information until the IGRP-derived information reappears.
Default Distance Value TableThis table lists the administrative distance default values of the protocols that Cisco supports:
Route SourceDefault Distance Values
Connected interface0
Static route1
Enhanced Interior Gateway Routing Protocol (EIGRP) summary route5
External Border Gateway Protocol (BGP)20
Internal EIGRP90
IGRP100
OSPF110
Intermediate System-to-Intermediate System (IS-IS)115
Routing Information Protocol (RIP)120
Exterior Gateway Protocol (EGP)140
On Demand Routing (ODR)160
External EIGRP170
Internal BGP200
Unknown*255
* If the administrative distance is 255, the router does not believe the source of that route and does not install the route in the routing table.
RIP:The Routing Information Protocol (RIP) is a distance-vector,interior gateway (IGP) routing protocol used by routers to exchange routing information.RIP uses the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops allowed for RIP is 15. This hop limit, however, also limits the size of networks that RIP can support.RIP version 2 (RIPv2) was developed due to the deficiencies of the original RIP.
Difference between RIPv1 and RIPv2:
RIPv2 is actually an enhancement of RIPv1's features and extensions raether than an entirely new protocol.
1) RIPv1 is Classful routing protocol and RIPv2 Classless routing protocol.
2) In RIPv1, subnet masks are NOT included in the routing update and In RIPv2 Subnet masks are included in the routing update.
3) RIPv2 multicasts the entire routing table to all adjacent routers at the address 224.0.0.9, as opposed to RIPv1 which uses broadcast (255.255.255.255). Unicast addressing is still allowed for special applications.
Basic Configuration:
Cisco IOS, uses "router rip" command to enable RIP routing protocol. The version command is used to specify which RIP version to use (either 1 or 2). If the version command is omitted then the router defaults to sending RIPv1 but can receive both RIPv1 and RIPv2.
The "network" command is used to specify the directly connected subnets on the router to be configured and that are intended to be included in the routing updates.
According to the classful, network specified, the subnets of that network are automatically identified and participate in the routing update. By default routing updates are summarized at network boundaries.
In RIPv2 this auto summarization behavior can be turned off using the "no auto-summary" command. Moreover, manual summarization can be configured on a per interface level.
Configuration Example:
R1#conf t
R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#network 192.168.12.0
R1(config-router)#exit
Verification:
R1#show ip protocolRouting Protocol is "rip"
Sending updates every 30 seconds, next due in 27 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Redistributing: rip
*   In RIP, we specify only those networks that belong to us. RIP sends routing table updates   to its neighbors for every 30secs. RIP uses hop count as a unit of metric. The administrative distance of RIP is 120 ** IGRP uses autonomous number system. Here, only the networks that come under the same autonomous system number will communicate with each other. Autonomous number is provided by ISP. (By default, networks in different Autonomous system will not communicate, for different Autonomous systems to communicate redistribution should be done - CCNP concept).
 IGRP sends updates for every 90secs and uses bandwidth and delay as unit of metric. IGRP has an administrative distance of 100  

Time Intervals

RIP

IGRP

Update Interval

30

90

Hold-down timer

180

280

Invalid after

180

270

Flushed after

240

630
  •  Update: this is how often we send routing updates, the default is 30 seconds.
    • Invalid: the number of seconds since we received the last valid update, once this timer expires the route goes into holddown, the default is 180 seconds.
    • Holddown: the number of seconds that we wait before we accept any new updates for the route that is in holddown, the default is 180 seconds,
    • Flush: how many seconds since we received the last valid update until we throw the route away, the default is 240 seconds.
     

    Interior Gateway Routing Protocol

    Routing Information Protocol
    Uses autonomous number system.
    Does not use autonomous number system.
    Works only on Cisco routers.
    Works on multi-vendor routers.
    Sends updates for every 90secs.
    Sends updates for every 30secs.
    Bandwidth, delay and distance as a unit of metric.
    Hop count as a unit of metric.

    Administrative distance is 100

    Administrative distance is 120

    Has a maximum hop count of 100

    Has a maximum hop count of 16
     
    Sl. No

    OSPF

    EIGRP
    1
    Link state.
    Hybrid(DV + LS).
    2
    Open protocol (multi-vendor).
    Cisco Proprietary Protocol.
    3

    Supports only IP protocol.
    Supports multiple protocols like
    IP, IPX, Apple Talk etc.,
    4
    Cost = 108 / Bandwidth.
    Cost is calculated based on the Bandwidth, Delay etc.,
    5
    Link State Advertisement (LSA) is made. (State of Link is broadcasted).
    Routing Table is sent.
    6
    For every 10 sec a Hello packet is sent.
    For every 5 sec a Hello packet is sent.
    7
    For every 30 min LSA is broadcasted.
    Broadcast is sent only when there is a change in the Routing table.
    8
    When the Link goes down OSPF needs to run the SPF algorithm again.
    When the link goes down EIGRP proceeds with the Next Best Path (Feasible Successor).
    9
    Area is used for administrative convenience of a large network
    Autonomous System is used for administrative convenience of a large network
    10
    Uses Dijsktra algorithm to find the best path (Shortest path).
    Uses DUAL (Diffusing Update Algorithm) is used to find the best path.

    A distance-vector routing protocol in data networks determines the best route for data packets based on distance. Distance-vector routing protocols measure the distance by the number of routers a packet has to pass, one router counts as one hop. Some distance-vector protocols also take into account network latency and other factors that influence traffic on a given route. To determine the best route across a network routers on which a distance-vector protocol is implemented exchange information with one another, usually routing tables plus hop counts for destination networks and possibly other traffic information. Distance-vector routing protocols also require that a router informs its neighbours of network topology changes periodically.
    The link-state protocol is performed by every switching node in the network (i.e., nodes that are prepared to forward packets; in the Internet, these are called routers). The basic concept of link-state routing is that every node constructs a map of the connectivity to the network, in the form of a graph, showing which nodes are connected to which other nodes. Each node then independently calculates the next best logical path from it to every possible destination in the network. Each collection of best paths will then form each node's routing table.
    This contrasts with distance-vector routing protocols, which work by having each node share its routing table with its neighbours. In a link-state protocol the only information passed between nodes is connectivity related. Link-state algorithms are sometimes characterized informally as each router, "telling the world about its neighbours."
     

    Sl.
    No

    Distance vector

    Link state

    1

    Considers only distance.

    Bandwidth, delay, load, Reliability and MTU.

    2

    Sends the routing table.

    Sends the state of the link.

    3

    Learns about the adjacent routers.

    Learns the entire topology. 
    1) Distance Vector

        Uses Bellman-Ford algorithm to calculate the hops and direction of routes.Ex EIGRP,RIP,IGRP
       Interior Gateway Protocol (IGP)

    2) Link-state

        Builds a tree of shortest-path-first (SPF) links by running Dijkstra algorithm.Ex OSPF
           Interior Gateway Protocol (IGP)

    3) Hibrid

        Has similarities with both, distance vector and Link-state protocols. Uses Diffusing Update Algorithm (DUAL).Ex EIGRP
           Interior Gateway Protocol (IGP)

    4) Path-Vector

        Used in the Internet, Builds paths between Autonomous Systems. Ex BGP
       Exterior Gateway Protocol (EGP)

    BGP:Border Gateway Protocol (BGP) is a standardized exterior gateway protocol designed to exchange routing and reachability information among autonomous systems (AS) on the Internet.[1] The protocol is classified as a path vector protocol.[2] The Border Gateway Protocol makes routing decisions based on paths, network policies, or rule-sets configured by a network administrator and is involved in making core routing decisionsBGP sends updated router table information only when something changes -- and even then, it sends only the affected information. BGP has no automatic discovery mechanism, which means connections between peers have to be set up manually, with peer addresses programmed in at both ends.
    BGP makes best-path decisions based on current reachability, hop counts and other path characteristics. In situations where multiple paths are available -- as within a major hosting facility -- BGP can be used to communicate an organization's own preferences in terms of what path traffic should follow in and out of its networks. BGP even has a mechanism for defining arbitrary tags, called communities, which can be used to control route advertisement behavior by mutual agreement among peers.

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