Wednesday, May 9, 2007

ROUTER Configuration (part: II)

Static and Dynamic Routers

For routing between routers to work efficiently in an internetwork, routers must have knowledge of other network IDs or be configured with a default route. On large internetwork, the routing tables must be maintained so that the traffic always travels along optimal paths. How the routing tables are maintained defines the distinction between static and dynamic routing.

Static Routing

A router with manually configured routing tables is known as a static router. A network administrator, with knowledge of the internetwork topology, manually builds and updates the routing table, programming all routes in the routing table. Static routers can work well for small internetworks but do not scale well to large or dynamically changing internetworks due to their manual administration.

Static routers are not fault tolerant. The lifetime of a manually configured static route is infinite and, therefore, static routers do not sense and recover from downed routers or downed links.

A good example of a static router is a multihomed computer running Windows 2000 (a computer with multiple network interface cards). Creating a static IP router with Windows 2000 is as simple as installing multiple network interface cards, configuring TCP/IP, and enabling IP routing.

Dynamic Routing

A router with dynamically configured routing tables is known as a dynamic router. Dynamic routing consists of routing tables that are built and maintained automatically through an ongoing communication between routers. This communication is facilitated by a routing protocol, a series of periodic or on-demand messages containing routing information that is exchanged between routers. Except for their initial configuration, dynamic routers require little ongoing maintenance, and therefore can scale to larger internetworks.

Dynamic routing is fault tolerant. Dynamic routes learned from other routers have a finite lifetime. If a router or link goes down, the routers sense the change in the internetwork topology through the expiration of the lifetime of the learned route in the routing table. This change can then be propagated to other routers so that all the routers on the internetwork become aware of the new internetwork topology.

The ability to scale and recover from internetwork faults makes dynamic routing the better choice for medium, large, and very large internetworks.

A good example of a dynamic router is a computer with Windows 2000 Server and the Routing and Remote Access Service running the Routing Information Protocol (RIP) and Open Shortest Path First (OSPF) routing protocols for IP and RIP for IPX.

TCP/IP Interior Routing Protocols (RIP, OSPF, GGP, HELLO, IGRP, EIGRP)

Modern TCP/IP routing architecture groups routers into autonomous systems (ASes) that are independently controlled by different organizations and companies. The routing protocols used to facilitate the exchange of routing information between routers within an AS are called interior routing protocols (or historically, interior gateway protocols). Since most network administrators are responsible for routers within a particular organization, these are the routing protocols you are most likely to deal with unless you become a major Internet big-shot.

One of the benefits of autonomous systems architecture is that the details of what happens within an AS are hidden from the rest of the internetwork. This means that there is no need for universal agreement on a single "language" for an internet as is the case for exterior routing protocols. As a network administrator for an AS, you are free to choose whatever interior routing protocol best suits your networks. The result of this is that there is no agreement on the use of a single TCP/IP interior routing protocol. There are several common ones in use today, though as is usually the case, some are more popular than others.

TCP/IP Routing Information Protocol (RIP, RIP-2 and RIPng):

The most popular of the TCP/IP interior routing protocols is the Routing Information Protocol (RIP). The simplicity of the name matches the simplicity of the protocol—RIP is one of the easiest to configure and least resource-demanding of all the routing protocols. Its popularity is due both to this simplicity and its long history. In fact, support for RIP has been built into operating systems for as long as TCP/IP itself has existed.

In this section I describe the characteristics and operation of the TCP/IP Routing Information Protocol (RIP). There are three versions of RIP: RIP versions 1 and 2 for IP version 4 and RIPng (next generation) for IP version 6. The basic operation of the protocol is mostly the same for all three versions, but there are also some notable differences between them, especially in terms of the format of messages sent.

For this reason, I have divided my description of RIP into two subsections. In the first, I describe the fundamental attributes of RIP and its operation in general terms for all three versions. In the second, I take a closer look at each version, showing the message format used for each and discussing version-specific features as well.

Open Shortest Path First (OSPF):

Interior routing protocols using a distance-vector routing algorithm, such as the Routing Information Protocol (RIP), have a long history and work well in a small group of routers. However, they also have some serious limitations in both scalability and performance that makes them poorly-suited to larger autonomous systems or those with specific performance issues. Many organizations that start out using RIP quickly found that its restrictions and issues made it less than ideal.

To solve this problem, a new routing protocol was developed in the late 1980s that uses the more capable (and more complex) link-state or shortest path first routing algorithm. This protocol is called Open Shortest Path First (OSPF). It fixes many of the issues with RIP and allows routes to be selected dynamically based on the current state of the network, not just a static picture of how routers are connected. It also includes numerous advanced features, including support for a hierarchical topology and automatic load sharing amongst routes. On the downside, it is a complicated protocol, which means it is often not used unless it is really needed. This makes it the complement of RIP and is the reason they both have a place in the spectrum of TCP/IP routing protocols.

Gateway-to-Gateway Protocol (GGP):

GGP is a MILNET protocol specifying how core routers (gateways) should exchange reachability and routing information. GGP uses a distributed shortest-path algorithm. The Gateway-to-Gateway Protocol is obsolete.


HELLO protocol is an early version of routing protocol for TCP/IP network using a distance-vector algorithm. HELLO does not use hop count as a metric. Instead, it attempts to select the best route by assessing network delays and choosing the path with the shortest delay. HELLO protocols also contain routing information in the form of a set of destinations that the sending router is able to reach and a metric for each. The HELLO protocol was developed in the early 1980s and documented in RFC 891. The name “HELLO” is capitalized and it should not be confused with the hello process used by a few protocols.

IGRP: Interior Gateway Routing Protocol:

The Interior Gateway Routing Protocol (IGRP) is a routing protocol to provide routing within an autonomous system (AS). In the mid-1980s, the most popular interior routing protocol was the Routing Information Protocol (RIP). Although RIP was quite useful for routing within small- to moderate-sized, relatively homogeneous internetworks, its limits were being pushed by network growth. The popularity of Cisco routers and the robustness of IGRP encouraged many organizations with large internetworks to replace RIP with IGRP.

EIGRP: Enhanced Interior Gateway Routing Protocol:

Enhanced Interior Gateway Routing Protocol (EIGRP) is an enhanced version of IGRP. IGRP is Cisco's Interior Gateway Routing Protocol used in TCP/IP and OSI internets. It is regarded as an interior gateway protocol (IGP) but has also been used extensively as an exterior gateway protocol for inter-domain routing.

ROUTER Concept:

Before we know more about how to configure Cisco Router, we have to know the basic rule of routing concept, how to assigned IP number, subnetting, netmasking and others related to the routing concept.


Host A : (C network class subnet :
Host B : (C network class subnet :
Host C : (C network class subnet :
Host D : (C network class subnet :

A Host able to communicate with B Host (see the subnet)

A Host to C Host or A Host to D Host cannot communicate (see the subnet)

B Host to C Host or B Host to D Host cannot communicate (see the subnet)

The question:

How to connect between A host and C Host ?


We can connect between different subnet Host with ROUTER.

How to run new Router to connect between different host ? (see my case)

Case :
We have two factory with different area and of course got network each factory. My Boss need to connect between factory, let's say Factory Stc and factory Ltx. Stc Factory is a data central and as a gateway for internet connection, because no internet connection around location of
Ltx factory. (see the scheme picture)

What we have to do once get the router...?

to be continued....!


Original Template | by: Elque 2007 | Modify by : Jan Pieter Marbun (June 2007)