Ebook What Is Router??

Jakarta (ANTARA News) - Minister of Communication and Information (Menkominfo) Muhammad Nuh said his side will launch the WiMAX (Worldwide Interoperability for Microwave Access) version of Indonesia momentum in the 1000 years of national 28 May 2008.

"We will launch the WiMAX version of Indonesia on 28 May 2008 later. This is a national pride in the areas of technology," said Menkominfo in Society Meeting Listen to the RI House of Representatives Commission I on the parliament building in Jakarta on Monday.

He said the project WiMAX version of Indonesia is currently in the research conducted Depkominfo together with BPPT, LIPI and RISTEK.

"It's research. We have research as part of WiMAX is still separate, still not in the form of a whole. We have a job to combine all this with the orientation of the end product," said Noah.

Research project with the need to koordMengapa router

Before we learn more about how to configure cisco router, we need to understand more about some of the basic routing rule. Also of course we must understand the numbering system IP, subnetting, netmasking and his brothers.

Sample cases:

X à host 128.1.1.1 (ip Class B network 128.1.xx ps)

Y à host 128.1.1.7 (class B IP network id 128.1.xx)

Host à Z 128.2.2.1 (class B IP network id 128.2.xx)

In the case above, the host X and Y can communicate with the host directly, but the host X and Y can not communicate with host Z, because they have a different network Id. How does that Z can communicate with X and Y? use a router!

Example use cases subnetting

Host P à 128.1.208.1 subnet mask 255.255.240.0

Q à Host 128.1.208.2 subnet mask 255.255.240.0

Host R à 128.1.80.3 subnet mask 255.255.240.0

Well, when subnetting is, the two hosts are connected to the same network segment can communicate only if both the network id and subnetid its sesuai.Pada case above, P and Q can communicate with directly, R have the same network id with P and Q, but have different subnetidyang. Thus R can not communicate directly with P and Q. How that can communicate with the R P and Q? use a router!

So the router, it can be said easily, connecting two different networks, precisely direct the best route to achieve the expected network

In the implementation, the router used to connect a network between institutions or companies that each have a network with different network id. Other examples that are popular at this time when your company will be connected to the internet. Then the router will work stream packet data from your company to other institutions via the internet, be sure the network you will be calm with which you perushaaan direction.

If a network connecting the 2 units, in fact you can also use Windows NT based pc or linux. With 2 network cards and the setting a bit, actually you have to make practical router. But of course with all keterbatasannya.

In the market is very diverse brand router, such baynetworks, 3COM and cisco. Module course this time we will discuss specific cisco. Why? because it is a cisco router which is widely used and became standard for many other products.

More about the routing

Data from devices connected to the Internet are sent in the form of a datagram, the packet data that is defined by IP. Datagram packet has a destination address data; Internet Protocol addresses to check the original datagram from the device to the destination device. If the datagram's destination address is a network device with the original datagram delivered directly to the device that goal. If the datagram destination address was not found in the same network, datagram to the router was the most appropriate (the best available router).

IP Router (usually just called a router) is a device that functions to forward the datagram to the IP network layer. Router has more than one antamuka network (network interface) and can forward the datagram from one interface to another interface. For each datagram is received, the router checks whether the datagram was addressed to himself. If that is addressed to the router, the datagram was delivered to the transport layer.

If the datagram not addressed to the router, which will be forwarding table is held to decide where it should datagram is intended. Forwarding table is a table consisting of a pair of IP addresses (host address or network address), router address below, and the place of outgoing datagram.

If a line does not find any in the forwarding table according to the destination address, the router will give the message to the sender that the address is not accessible. This incident can dianalogikan with the message "return to sender" on the regular mail. A router can also inform him that the answer to the router is not a destination, and encourage the use of another router. With the third function of the router, the hosts in the Internet can be connected to each other.

Static and Dynamic

In general, routing coordination mechanisms can be divided into two: static routing and dynamic routing. In the static routing, entries in the router forwarding table filled and removed manually, while the dynamic changes in the routing is done through routing protocols. Static routing is the most simple of routing can be done on the computer network. Using pure static routing in a network means that the filling in each entry in the forwarding table of each router in the network.

The use of static routing in a network that small is not necessarily a problem, only a few entries that need to diisikan in the forwarding table in each router. But you can certainly imagine what if must complete the forwarding table of each router in the amount not less in a network that big. Especially if you are assigned to fill the entries in the router on the Internet that many in number and growing every day. Of all occupied!

Dynamic routing is the way used to release the obligation fill entry-forwarding table entries manually. Routing protocol, set the router-router so that it can communicate with each other and give each other routing information that can change the content of forwarding table, depending on the network. In this way, the router-router knows the network is able to last and to forward the datagram in the right direction.

Interior Routing Protocol

In the early 1980s, the Internet is limited to the ARPANET, Satnet (ARPANET expansion of satellite use), and some of the local network that is connected via the gateway. In its development, the Internet requires a hierarchical structure to anticipate the network has become large. Internet and then into some Autonomous system (AS) and the current Internet consists of thousands of U.S.. Each AS has a mechanism for exchange of routing information and the collection itself.

The protocol used to exchange routing information in the U.S. are classified as interior routing protocol (IRP). The routing information is then submitted to the U.S. in the form of reachability information. Reachability information is issued by a U.S. contains information about networks that can be achieved through the U.S. and become U.S. indicators terhubungnya to the Internet. Delivery-reachability information between the U.S. are conducted using protocols that are classified as exterior routing protocol (ERP).

IRP is made standard on the Internet so far is Routing Information Protocol (RIP) and Open shortest Path First (OSPF). In addition to the second protocol, there is also this kind of routing protocol that is proprietary but widely used in the Internet, the Internet Gateway Routing Protocol (IGRP) from Cisco Systems. IGRP protocol and then expanded into the Extended IGRP (EIGRP). All routing protocols use the above metrics as a basis to determine the best path that can be adopted by datagram. Metrics associated with the "cost" that are on each link, which can be a throughput (data rate), delay, cost of connection, and link reliability.

I. Routing Information Protocol

RIP (acronym, read as rip) included in the distance-vector protocol, a protocol that is very simple. Distance-vector protocol, often called the Bellman-Ford protocol, because it comes from the distance calculation algorithm cut by RE Bellman, and has been described in the form of algorithms-terdistribusi first by Ford and Fulkerson.

Each router with a distance-vector protocol, when first run only to find out how routing itself (local information) and network topology do not know the place is located. Router then sends the information in the form of a local distance-vector to all the links that connect directly to it. Router receives a routing information calculate distance-vector, adding a distance-vector with the link metric information received, and include entry into the forwarding table if the path is considered best. Information after the addition of routing metrics and sent again to all the router, and this should be done every time a certain interval. So forth so that all routers in the network to know the network topology.

Distance-vector protocols have weaknesses which can be seen in the network when there is a link that is lost. Two possible failure that may occur is the effect and calculate the bounce-to-no-to (counting to infinity). Bounce effects can occur on the network that use different metrics in at least a link. Links that can cause dropouts routing loop, so that the datagram through a particular link only reel in between two routers (bounce) until the age (time to live) datagram is finished.

Count-to-not-going until too late because the router you that a link is lost. This delay causes the router must send and receive distance-vector and the metrics to the maximum metric distance-vector is reached. The link stated after dropping out of distance-vector reached the maximum metric. At the time of the metrics is also routing loop occurs, even for a longer time than occurs when the bounce effect ..

RIP does not adopt the distance-vector protocol, as such, but with some improvements in the routing loop algoritmanya that happens can be minimized. RIP Split horizon is used to minimize the effect of bounce. The principle used split horizon is simple: if node A datagram to the destination X through node B, then for B does not make sense to achieve the goal through X A. Thus, A does not need to notify B that X can be achieved through A. B

To prevent the case-to-no-to, using the method Triggered RIP Update. RIP has a timer to determine when the router must re-routing information. If there are changes in the network, while the timer has not been exhausted, the router must send the routing information triggered by the changes (triggered updates). Thus, the router-router in the network can quickly find out the changes that occur and minimize the possibility of routing loop occurs.

RIP is defined in RFC-1058 using the metric between 1 and 15, while 16 are considered as no-till. Route with the distance-vector 16 is not included in the forwarding table. Quoting prevents this 16 metric calculates the time-to-no-till is too long. RIP packets are normally sent every 30 seconds or more quickly if there is triggered updates. In 180 seconds if a route is not maintained, the router route delete entries from the forwarding table. RIP does not have the information about each subnet route. Router must assume that each route has received the same subnet with the subnet on the router. Thus, RIP does not support Variable Length subnet masks (VLSM).

RIP version 2 (RIP-2, or RIPv2), attempted to produce some improvements over RIP, including support for VLSM, using authentication, provide the following information hop (next hop), and multicast. Addition information on the subnet mask of each route does not make a router must assume that route have the same subnet mask with the subnet mask is used to it.

RIP-2 also uses authentication to be able to know the routing information which can be trusted. Authentication is required on the routing protocol to create a protocol to be more secure. RIP-1 does not use authentication, so people can give the false routing information. Next hop information in RIP-2 is used by router to inform a route but the route to reach the router does not pass that information, but the other router. Use the following usually hop on the border between the U.S..

RIP-1 broadcast address to use to send the routing information. As a result, the packet is received by all hosts in the subnet and add the burden of the host. RIP-2 can transmit packets using IP multicast on 224.0.0.9 so that not all hosts need to receive and process the routing information. Only the router-router that uses RIP-2 that receive routing information without need to disrupt the hosts in another subnet.

RIP is a routing protocol is simple, and this is the reason why RIP is implemented in most networks. Set the routing using RIP and not complex enough to provide results that can be received, especially if the rare failure of a network link. However, for large networks and complex, RIP may not be enough. In such conditions, the calculation in the RIP routing often requires a long time, and caused a routing loop. For a network like this, most computer network specialist who entered the protocol in the group link-state

II. Open shortest Path First (OSPF)

Link-state technology developed for the ARPAnet in the protocol that terdistribusi far better than distance-vector protocol. Instead of exchange distance (distance) to the destination, each router in the network has a network map that can be updated quickly after each topology change. Map this route is used to calculate a more accurate than using the distance-vector protocol. The development of this technology eventually produce protocol Open shortest Path First (OSPF), which was developed by IETF for use on the Internet. Even now the Internet Architecture Board (IAB) has recommended the OSPF instead of RIP.

The principle of link-state routing is simple. As the route of "best" way terdistribusi, all routers have a map of all network and calculate the best route out of this map. Map of the network are stored in a database and each record in the database says is a link in the network. Record-record is sent by the router that is connected directly with each link.

Because each router should have a network map that describes the condition of the last complete network topology, any changes in the network must be followed by changes in the database link-state located on each router. Link status change detected router will change the database link-state router, the router and then send the changes to the router, another router.

The protocol used to transmit this change must be fast and reliable. This can be achieved by flooding protocol. In the flooding protocol, messages sent are the changes from the database and the message number order. By sending only changes the database, the time needed for sending and processing messages are less dibandingdengan send the entire data base. Ordinal number a message needed to determine whether the message is received later than that found in the database. Ordinal numbers are useful in case the link is dropped out to become connected again.

At the time there is a link to drop out and become a separate network, the second data base network will be different. When the link is dropping out of life again, all databases in the router must reconcile. The database will not return the same to send a message with the link-state only. The process equation in the router database which are referred to as the adjacency. Two routers are referred to as adjacent if the database link-state both have the same. In this process, the two routers do not exchange data base because it will require a long time.

The process of the adjacency of two fasa.Fasa first, the two routers exchange database description is a summary of the data base of the each router. Each router then compares the description database received basis with the available data. In the second phase, each router ask neighbors to send the record-record database is different, that is when the router does not have a record, or ordinal number of the record is smaller than the description sent by the database. After this process, the router and update some records and then sent to this router-router protocol through flooding.

Link-state protocol is better than distance-vector protocol is caused by several things: the time required for convergent faster, and more importantly this protocol does not produce routing loop. This protocol supports the use of several metrics at once. Throughput, delay, cost and reliability are the metrics-metrics that are commonly used in the network. In addition, this protocol can also generate many paths to a destination. Suppose a router has two routes with the same metrics to host B. Protocol can enter a second line to the forwarding table so that the router is able to share the load between the two lines is.

Draft OSPF uses link-state protocol with some additional functions. Functions were added, among others, supports multi-access network, such as X.25 and Ethernet, network and share some of the big mejadi area.

Has been described above that each router in link-state protocol will need to establish adjacency with the neighboring router. On multi-access network, each neighboring router can be more than one. In situations like this, each router in the network need to establish adjacency with all the other router, and it is not efficient. OSPF mengefisienkan adjacency with introducing the concept of designated routers and backup designated router. All routers need only adjacent to the designated router, so that only the designated router adjacent to the router all the others. Backup Designated router akan took over the functions of the designated router fails to work.

The first step in a multi-access network is to select the designated router and back up. This election to include in the Hello protocol, the protocol in OSPF neighbors to know neighbors, each router in the link. After the election, a new router and router-form adjacency with the designated router and back up. Every network change occurs, the router sends a message using the flooding protocol to designated router, designated router and send a message to the router-router link in the other.

Backup Designated router also listen to messages sent to the designated router. If the designated router fails, back up and become the designated router and the new designated router selected a new backup. Because the designated router that was adjacent to the new router-router other, need not be done again the equation database that requires a long time is.

In a large network of databases that are required also to save a large network topology. This leads to memory router needs a larger calculation time and the longer route. To anticipate this, OSPF uses the concept of area and the backbone. Network is divided into several areas that are connected to the backbone. Each area is considered as network and router-router in it only needs to have a network topology map in the area. Router-router that is located on the border between the area only to send a summary of the links found in the area and does not send a topology one area to another area. Thus, the calculation becomes simpler route.

Simplicity vs. Ability

We already see a glimpse how the RIP and OSPF work. Each routing protocol has advantages and kekurangannya respectively. RIP protocol is very simple and easy to implement but can cause a routing loop. OSPF protocol is a protocol, a more complex and better than RIP, but requires memory and CPU time is large.

In many places there is also a combination of using static routing, RIP, RIP-v2 and OSPF. The results in this network indicates that the administration of static routing is much more time consuming than the dynamic routing. Observations on the dynamic routing protocol, also showed that the RIP uses bandwidth more than the OSPF and the larger network, the bandwidth used RIP grow larger as well. So, if you are designing the network TCP / IP which is a large selection of OSPF routing protocol that tepatinator Depkominfo for using the budget of the Department will incorporate a variety of research about WiMAX being one part and the end result a WiMAX version of the product of Indonesia.

Although fully funded by Depkominfo, Noah is reluctant to mention the cost needed in the project.

WiMAX is one technology that allows people to get a quality Internet connection and perform the activities of telecommunication and wireless technology-based Internet Protocol (VoIP ).(*)