Difference between Static, Dynamic and Default Routing

What is Routing?

Routing is a process of finding the available paths (also called Routes) to reach a particular destination, It will maintain a table with a best path or Route out of all available paths or routes to a particular destination is called Routing table, Routing is usually performed by a dedicated device called a Router.

Routing  specifies how the routers communicate, disseminating the information which enables the routers to be selected between two nodes in a network. Routing protocol interacts and informs the hardware that is needed to transmit the data between transmitter and the receiver for transmission over network.

Types of Routing 

There are three basic methods to build a routing table on any Networking Device.

 1. Static Routing

2. Dynamic Routing

3. Default Routing

 

Static Routing:

A static routing occurs when you manually add routes in each Router’s Routing table, Routing table should create, maintain, and update by a network administrator, manually. A static route to every network must be configured on every router for full connectivity. This provides a granular level of control over routing, but quickly becomes impractical on large networks. Routers will not share static routes with each other, thus reducing CPU/RAM overhead and saving bandwidth. However, static routing is not fault-tolerant, as any change to the routing infrastructure (such as a link going down, or a new network added) requires manual intervention. Routers operating in a purely static environment cannot seamlessly choose a better Route if a link becomes unavailable. Static routes have an Administrative Distance (AD) of 1, and thus are always preferred over dynamic routes, unless the default AD is changed. A static route with an adjusted AD is called a floating static route.

Command Syntax for Static Routing on Cisco Router

The syntax for the global configuration command used to enter a static route is:

ip route {destination prefix} {destination prefix mask} {Exit interface OR Next hop IP address} {Administrative Distance} {Permanent}

The following briefly outlines the advantages and disadvantages of static routing:

Advantages of Static Routing:

1. Minimal CPU/Memory overhead

2. There is no bandwidth update between Routers, which means you will save bandwidth on WAN links.

3. It adds security because the administrator can choose Routing access to certain networks only.

Disadvantages of Static Routing:

1. If any Infrastructure changes must be manually adjust the configuration in complete network.

2. No “dynamic” fault tolerance if a link goes down

3. Administrator must understand the complete internetwork and how each Router connected to configure properly.

4. Impractical on large network

 

Dynamic Routing:

A Dynamic Routing is when protocols are used to find networks and update Routing tables on Routers. A dynamic routing table is created, maintained, and updated by a routing protocol running on the router. Examples of routing protocols include RIP (Routing Information Protocol), EIGRP (Enhanced Interior Gateway Routing Protocol), and OSPF (Open Shortest Path First). Routers do share dynamic routing information with each other, which increases CPU, RAM, and bandwidth usage. However, routing protocols are capable of dynamically choosing a different (or better) path when there is a change to the routing infrastructure.

Difference between Routing Protocols and Routed Protocols

Do not confuse routing protocols with routed protocols:

A routed protocol is a Layer 3 protocol that applies logical addresses to devices and routes data between networks (such as IP)

A routing protocol dynamically builds the network, topology, and next hop information in routing tables (such as RIP, EIGRP, etc.)

The following briefly outlines the advantages and disadvantages of dynamic routing:

Advantages of Dynamic Routing:

1. Simpler to configure on larger networks

2. Will dynamically choose a different (or better) route if a link goes down

3. Ability to load balance between multiple links

Disadvantages of Dynamic Routing:

1. Updates are shared between routers, thus consuming bandwidth

2. Routing protocols put additional load on router CPU/RAM

3. The choice of the “best route” is in the hands of the routing protocol, and not the network administrator.

Default Routing:

A default routing is used only when one exit path from the Router. Default Routing  can configure like a static route with the ip route command, but use 0.0.0.0 0.0.0.0 for the IP network and subnet mask followed by the next hop router’s IP address or Exit interface of the  local Router.  Have to also use the ip classless command since there aren’t any routes in the routing table.  ip classless is enabled by default in IOS version 12.

Command Syntax for Default Routing on Cisco Router

Router(config)#ip route 0.0.0.0 0.0.0.0 192.168.1.2
   Router(config)#ip classless

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  1. viven says:

    Nice post! very informative on Routing and different types of Routing also. Thanks…

  2. John says:

    Differences between static routing and dynamic routing:

    Static Routing:

    Manually set up route.
    Stable. No impact of traffic and transmission failures

    Dynamic Routing:

    Route setting is automatic
    Responds to the changes of the network
    Optimized route is selected automatically.

  3. Vimal says:

    Wonderful I understand completely about routing and routing types, Very informative blog.

  4. Sdas says:

    Thanks for sharing about differences between all Routing protocols 🙂

  5. Prem says:

    Static routing is configured by the network administrator and is not capable of adjusting to changes in the network without network administrator intervention. Dynamic routing adjusts to changing network circumstances by analyzing incoming routing update messages without administrator intervention.

  6. Sayeed says:

    Find the difference between Static and Dynamic Routing

    In the static routing, the routes are manually added to the routing table by the Network administrator.

    In the dynamic routing, the routes are dynamically added to the routing table by using Routing protocol as per the changes in network topology.

  7. Jaivir says:

    Static routing is when you statically configure on a Router to send traffic for particular destinations in predefined directions.

    Dynamic routing is when you use a routing protocol such as OSPF, ISIS, EIGRP, and/or BGP to find out what paths should take to send a traffic to the particular destination.

    There are very few situations in the real world where you would use one method of routing exclusively. A typical network will use a dynamic protocol such as OSPF to determine the best routes within an enterprise, BGP to determine the best exit points to the rest of the Internet, and static routing to glue it all together with reasonable default routes, and to send specific traffic over specific paths for traffic engineering reasons.

  8. Zinal says:

    nic website

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