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| Cosco elearning |
| elerning networking with cisco ccna,ccnp,ccdp,artcle cisco by for elearning beginers, His current consulting work focuses on network and Voice over IP (VoIP) |
| Language: English |
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| Role Of The Router |
| 2009-12-20 12:54:51 |
The router is a special-purpose computer that plays a key role in the operation of any data network. Routers are primarily responsible for interconnecting networks by:
Determining the best path to send packets
Forwarding packets toward their destination
Routers perform packet forwarding by learning about remote networks and maintaining routing information. The router is the junction or intersection that connects multiple IP networks. The routers primary forwarding decision is based on Layer 3 information, the destination IP address.
The router's routing table is used to find the best match between the destination IP of a packet and a network address in the routing table. The routing table will ultimately determine the exit interface to forward the packet and the router will encapsulate that packet in the appropriated data link frame for that outgoing interface.
Related Topic Router
Dinamic Routing
Static Routing
Basic Routing Configuration
Routing Tables Principles
Router Interface
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| Router Connections |
| 2009-12-20 12:51:03 |
Router Connections
Connecting a router to a network requires a router interface connector to be coupled with a cable connector. As you can see in the figure, Cisco routers support many different connector types.
Serial Connectors
Picture Router Connections
For WAN connections, Cisco routers support the EIA/TIA-232, EIA/TIA-449, V.35, X.21, and EIA/TIA-530 standards for serial connections, as shown. Memorizing these connection types is not important. Just know that a router has a DB-60 port that can support five different cabling standards. Because five different cable types are supported with this port, the port is sometimes called a five-in-one serial port. The other end of the serial cable is fitted with a connector that is appropriate to one of the five possible standards.
Note: The documentation for the device to which you want to connect should indicate the standard for that device.
Newer routers support the smart serial interface that allows for more data to be forwarded ...
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| Alexa traffic smallest |
| 2009-12-20 12:49:56 |
Alexa traffic is traffic to our blog, the more traffic to our blog the small number of nominal figures we blog in Alexa’s eyes, and this is a sign of good alexa toolbar although sometimes confusing. Alexa indeed apply logic to the google rankings, blogs, if we are considered “important” google, it will increase the nominal amount of numbers we blog on google, while Alexa, the more we visited blog other bloggers, the small number of our nominal Alexa. Alexa rating determines your blog. The higher the ranking of a blog, the more “job / task” that you will receive, and also the more money that flows to your paypal. There are a few tips that can improve the ranking in the Alexa blog. among others:
1. Alexa Widget
Place the Alexa site widget stat in your website. Alexa stat this site contains javascript that accompany every visitor data (ping) to the server so that Alexa Alexa statistics become more accurate.
Scriptnya can be taken at the Alexa website. Live copy and paste. No ...
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| Purpose and Command Syntax OF IP Route |
| 2009-12-20 12:49:43 |
Purpose and Command Syntax of ip route
As we have discussed previously, a router can learn about remote networks in one of two ways:
Manually, from configured static routes
Automatically, from a dynamic routing protocol
The rest of this chapter focuses on configuring static routes. Dynamic routing protocols are introduced in the next chapter.
Static routes
Static routes are commonly used when routing from a network to a stub network. A stub network is a network accessed by a single route. For an example, see the figure. Here we see that any network attached to R1 would only have one way to reach other destinations, whether to networks attached to R2 or to destinations beyond R2. Therefore, network 172.16.3.0 is a stub network and R1 is a stub router.
Running a routing protocol between R1 and R2 is a waste of resources because R1 has only one way out for sending non-local traffic. Therefore, static routes are configured for connectivity to remote networks that are not directly co...
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| The IP Route Command |
| 2009-12-20 12:49:25 |
The IP Route Command
The command for configuring a static route is ip route. The complete syntax for configuring a static route is:
Router(config)#ip route prefix mask {ip-address | interface-type interface-number [ip-address]} [distance] [name] [permanent] [tag tag]
Most of these parameters are not relevant for this chapter or for your CCNA studies. As shown in the figure, we will use a simpler version of the syntax:
Router(config)#ip route network-address subnet-mask {ip-address | exit-interface }
The following parameters are used:
network-address - Destination network address of the remote network to be added to the routing table
subnet-mask - Subnet mask of the remote network to be added to the routing table. The subnet mask can be modified to summarize a group of networks.
One or both of the following parameters must also be used:
ip-address - Commonly referred to as the next-hop router's IP address
exit-interface - Outgoing interface that would be used in forwarding pack...
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| Packet Fields and Frame Fields |
| 2009-04-27 03:19:16 |
As we discussed previously, routers make their primary forwarding decision by examining the destination IP address of a packet. Before sending a packet out the proper exit interface, the IP packet needs to be encapsulated into a Layer 2 data link frame. Later in this section we will follow an IP packet from source to destination, examining the encapsulation and decapsulation process at each router. But first, we will review the format of a Layer 3 IP packet and a Layer 2 Eternet frame.Internet Protocol (IP) Packet FormatThe Internet Protocol specified in RFC 791 defines the IP packet format. The IP packet header has specific fields that contain information about the packet and about the sending and receiving hosts. Below is a list of the fields in the IP header and a brief description for ...
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| Best Path Best Path And Metric |
| 2009-04-27 03:06:55 |
Determining a router's best path involves the evaluation of multiple paths to the same destination network and selecting the optimum or "shortest" path to reach that network. Whenever multiple paths to reach the same network exist, each path uses a different exit interface on the router to reach that network. The best path is selected by a routing protocol based on the value or metric it uses to determine the distance to reach a network. Some routing protocols, such as RIP, use simple hop-count, which the number of routers between a router and the destination network. Other routing protocols, such as OSPF, determine the shortest path by examining the bandwidth of the links, and using the links with the fastest bandwidth from a router to the destination network.Dynamic routing protocols typ...
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| Implementing Basic Addressing Schemes |
| 2009-04-27 03:02:39 |
When designing a new network or mapping an existing network, document the network. At a minimum, the documentation should include a topology diagram that indicates the physical connectivity and an addressing table that lists all of the following information:Device namesInterfaces used in the designIP addresses and subnet masksDefault gateway addresses for end devices, such as PCsPopulating an Address Table The figure shows a network topology with the devices interconnected and configured with IP addresses. Under the topology is a table used to document the network. The table is partially populated with the data documenting the network (devices, IP addresses, subnet masks, and interfaces).Router R1 and host PC1 are already documented. Finish populating the table and the blank spaces on the diagram dragging the pool of IP addresses shown below the table to the correct locations.http://feeds2.feedburner.com/CiscoElearningWithCcnaAndCcnp
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| Router Interface |
| 2009-04-27 02:53:23 |
Management PortsRouters have physical connectors that are used to manage the router. These connectors are known as management ports. Unlike Ethernet and serial interfaces, management ports are not used for packet forwarding. The most common management port is the console port. The console port is used to connect a terminal, or most often a PC running terminal emulator software, to configure the router without the need for network access to that router. The console port must be used during initial configuration of the router.Another management port is the auxiliary port. Not all routers have auxiliary ports. At times the auxiliary port can be used in ways similar to a console port. It can also be used to attach a modem. Auxiliary ports will not be used in this curriculum.The figure shows th...
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| Routers and the Network Layer |
| 2009-04-27 02:51:16 |
The main purpose of a router is to connect multiple networks and forward packets destined either for its own networks or other networks. A router is considered a Layer 3 device because its primary forwarding decision is based on the information in the Layer 3 IP packet, specifically the destination IP address. This process is known as routing.When a router receives a packet, it examines its destination IP address. If the destination IP address does not belong to any of the router's directly connected networks, the router must forward this packet to another router. In the figure, R1 examines the destination IP address of the packet. After searching the routing table, R1 forwards the packet onto R2. When R2 receives the packet, it also examines the packet's destination IP address. After sear...
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