1. www.professordkinney.com

2. Establishing Internet Connectivity 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group 3. Lessons Objectives: Understanding the TCP/IP Internet Understanding the TCP/IP Transport Addressing and Subnets Exploring the Functions of Routing Configuring a Cisco Router 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 4. TCP/IP (Transmission Control Protocol/Internet Protocol) is the basic communication language or protocol of the Internet. It can also be used as a communications protocol in a private network (either an intranet or an extranet). When you are set up with direct access to the Internet, your computer is provided with a copy of the TCP/IP program just as every other computer that you may send messages to or get information from also has a copy of TCP/IP. TCP/IP uses the client/server model of communication in which a computer user (a client) requests and is provided a service (such as sending a Web page) by another computer (a server) in the network. TCP/IP communication is primarily point-to-point, meaning each communication is from one point (or host computer) in the network to another point or host computer. Many Internet users are familiar with the even higher layer application protocols that use TCP/IP to get to the Internet. These include the World Wide Web's Hypertext Transfer Protocol (HTTP), the File Transfer Protocol (FTP), Telnet (Telnet) which lets you logon to remote computers, and the Simple Mail Transfer Protocol (SMTP). These and other protocols are often packaged together with TCP/IP as a "suite." 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 5. The TCP/IP Protocol Architecture Figure 2 shows the TCP/IP protocol architecture; this diagram is by no means exhaustive, but shows the major protocol and application components common to most commercial TCP/IP software packages and their relationship. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 6. The Network Interface Layer PPP It is worth spending a little bit of time discussing PPP because of its importance in Internet access today. As its name implies, PPP was designed to be used over point-to-point links. In fact, it is the prevalent IP encapsulation scheme for dedicated Internet access as well as dial-up access. One of the significant strengths of PPP is its ability to negotiate a number of things upon initial connection, including passwords, IP addresses, compression schemes, and encryption schemes. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity PPP Frame Format 7. PPP generally uses an HDLC-like (bit-oriented protocol) frame format as shown in Figure 3, although RFC 1661 does not demand use of HDLC. HDLC defines the first and last two fields in the frame: Flag: The 8-bit pattern "01111110" used to delimit the beginning and end of the transmission. Address: For PPP, uses the 8-bit broadcast address, "11111111". Frame Check Sequence (FCS): An 8-bit remainder from a cyclic redundancy check (CRC) calculation, used for bit error detection. The Internet Layer The Internet Protocol (RFC 791), provides services that are roughly equivalent to the OSI Network Layer. IP provides a datagram (connectionless) transport service across the network. This service is sometimes referred to as unreliable because the network does not guarantee delivery nor notify the end host system about packets lost due to errors or network congestion. IP datagrams contain a message, or one fragment of a message, that may be up to 65,535 bytes (octets) in length. IP does not provide a mechanism for flow control. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 8. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group IP Packet Header Format Establishing Internet Connectivity 9. IP Addresses IP (version 4) addresses are 32 bits in length (Figure 5). They are typically written as a sequence of four numbers, representing the decimal value of each of the address bytes. Since the values are separated by periods, the notation is referred to as dotted decimal. A sample IP address is 208.162.106.17. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group IP Address Format Establishing Internet Connectivity 10. The Transport Layer Protocols The TCP/IP protocol suite comprises two protocols that correspond roughly to the OSI Transport and Session Layers; these protocols are called the Transmission Control Protocol and the User Datagram Protocol (UDP) TCP TCP, described in RFC 793, provides a virtual circuit (connection-oriented) communication service across the network. TCP includes rules for formatting messages, establishing and terminating virtual circuits, sequencing, flow control, and error correction. Most of the applications in the TCP/IP suite operate over the reliable transport service provided by TCP. The TCP data unit is called a segment; the name is due to the fact that TCP does not recognize messages, per se, but merely sends a block of bytes from the byte stream between sender and receiver. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 11. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity TCP segment format 12. UDP UDP is described in RFC 768, provides an end-to-end datagram (connectionless) service. Some applications, such as those that involve a simple query and response, are better suited to the datagram service of UDP because there is no time lost to virtual circuit establishment and termination. UDP's primary function is to add a port number to the IP address to provide a socket for the application. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity UDP Datagram Format 13. Subnetting: Lets work by Example. Example 1: A service provider has given you the Class C network range 209.50.1.0. Your company must break the network into 20 separate subnets. Step 1) Determine the number of subnets and convert to binary - In this example, the binary representation of 20 = 00010100. Step 2) Reserve required bits in subnet mask and find incremental value - The binary value of 20 subnets tells us that we need at least 5 network bits to satisfy this requirement (since you cannot get the number 20 with any less than 5 bits 10100) - Our original subnet mask is 255.255.255.0 (Class C subnet) - The full binary representation of the subnet mask is as follows: 255.255.255.0 = 11111111.11111111.11111111.00000000 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 14. We must convert 5 of the client bits (0) to network bits (1) in order to satisfy the requirements: New Mask = 11111111.11111111.11111111.11111000 - If we convert the mask back to decimal, we now have the subnet mask that will be used on all the new networks 255.255.255.248 - Our increment bit is the last possible network bit, converted back to a binary number: New Mask = 11111111.11111111.11111111.1111(1)000 bit with the parenthesis is your increment bit. If you convert this bit to a decimal number, it becomes the number 8 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 15. Step 3) Use increment to find network ranges - Start with your given network address and add your increment to the subnetted octet: 209.50.1.0 209.50.1.8 209.50.1.16 etc - You can now fill in your end ranges, which is the last possible IP address before you start the next range 209.50.1.0 209.50.1.7 209.50.1.8 209.50.1.15 209.50.1.16 209.50.1.23 etc - You can then assign these ranges to your networks. Remember the first and last address from each range (network / broadcast IP) are unusable 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 16. Example 1: A service provider has given you the Class C network range 209.50.1.0. Your company must break the network into as many subnets as possible as long as there are at least 50 clients per network. Step 1) Determine the number of clients and convert to binary - In this example, the binary representation of 50 = 00110010 Step 2) Reserve required bits in subnet mask and find incremental value - The binary value of 50 clients tells us that we need at least 6 client bits to satisfy this requirement (since you cannot get the number 50 with any less than 6 bits 110010) - Our original subnet mask is 255.255.255.0 (Class C subnet) - The full binary representation of the subnet mask is as follows: 255.255.255.0 = 11111111.11111111.11111111.00000000 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 17. We must ensure 6 of the client bits (0) remain client bits (save the clients!) in order to satisfy the requirements. All other bits can become network bits: New Mask = 11111111.11111111.11111111.11 000000 note the 6 client bits that we have saved - If we convert the mask back to decimal, we now have the subnet mask that will be used on all the new networks 255.255.255.192 - Our increment bit is the last possible network bit, converted back to a binary number: New Mask = 11111111.11111111.11111111.1(1)000000 bit with the parenthesis is your increment bit. If you convert this bit to a decimal number, it becomes the number 64 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 18. Step 3) Use increment to find network ranges - Start with your given network address and add your increment to the subnetted octet: 209.50.1.0 209.50.1.64 209.50.1.128 209.50.1.192 - You can now fill in your end ranges, which is the last possible IP address before you start the next range 209.50.1.0 209.50.1.63 209.50.1.64 209.50.1.127 209.50.1.128 209.50.1.191 209.50.1.192 209.50.1.255 - You can then assign these ranges to your networks. Remember the first and last address from each range (network / broadcast IP) are unusable 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 19. When subnetting based on the number of networks, SUBTRACT 1 from the number When subnetting based on the number of hosts per network, ADD 1 to the number Follow these rules and you'll always be safe. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 20. Exploring the Functions of Routing we are going to explore the packet delivery process, from the routing perspective. We will see how one of the main functions of routing is to determine the optimal path across a routed network for IP packets. Routers: Routers implement layer 3 or network layer functions. Their main job is to forward packets based upon a routing table. When doing so, they also provide traffic segmentation, multiple broadcast domains, and define network layer addressing subnets and networks. Those networks are defined by router network adapters or ports to which IP addresses are assigned. Those IP addresses are typically the default gateway to PCs and servers or other networking devices. Routers also connect to service providers and act as gateways to other networks, typically found at the perimeter or edge of the network. Some of those network adapters will be other than Ethernet. They will have connectivity to serial interfaces, DSL connections, and other forms of WAN 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 21. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity Routers Router Functions The basic routing function can be split into two areas; one is to build a map of the network and for that routers typically use either static routing or dynamic routing protocols. With the help of dynamic routing protocols, routers will let other network devices know about not only the topology of the network but also about network changes. Static routing will be that static and will not adapt to network changes. Both models accomplish the task of building the map of the network in the form of the routing table. 22. The command and output shown here display the routing table on a Cisco router. With show IP route, an IOS device like this one could show the different destinations, the cost to get there, what is known as the administrative distance to define priorities for different routing protocols, and the next-hop to get to that destination. Notice how the routing protocol that learned that particular entry or destination is shown there in the first column. This is EIGRP, this is RIP, and this is OSPF. With this information, routers will be able to determine where to forward packets. They will do so by sending the packet to the next router in the path according to the info in the routing table. Notice then that routing is based on destination addresses. Path Determination During the process of path determination, the routers will consider multiple alternatives to get to the same place; those alternatives result from the redundancy built into most network designs. You want multiple paths, so that if one goes down, other alternatives will become available. In determining the best path, routers will consider several things. One of them is the source of the information, and so you could have multiple dynamic routing protocols or even static routing populating the routing table and telling the router what the options are. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 23. The second piece of information is the cost of taking each path, and knowing that the path is made up of multiple links or hops that are defined by other routers. Then we could add the concepts of the cost in the context of the total path, but that cost is nothing more than the sum of all the costs to reach each hop in the path. Well, the two decisions are ruled by different pieces of information, for example, in order to define a tie breaker between sources of information, the routers use the administrative distance, so if a routing protocol like OSPF is telling the router information on a destination and also RIP is telling that router information on the same destination, then the administrative distance will define who wins. Once the source is selected, then the cost is what matters; in other words, if OSPF is giving me the information on those two paths, then the cost of the path will define which one I take. This is similar to having two maps to drive from one city to the other. You first select which map you are going to follow and then if the map is giving you more than one option, then you will select the option according to perhaps the amount of time it takes or the amount of miles you have to drive for each option. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 24. Routing Tables So the routing table contains the network layer intelligence that tells the router how to forward packets to remote destinations. Initially, that routing table is made up of networks that are directly connected to the particular router. They are obviously shown as directly connected networks, after that the way to learn about remote destinations is by either populating the routing table with static routes in which an administrator will tell the router how to get to the destination or by populating the routing table via routing table advertisements coming from other routers. So routers are gossipy and they will tell each other information that allows them to know about all the gossip in the network. In both cases, static and dynamic routing notice how routers use the reserved subnet addresses or network addresses that contain all 0s in the host portion of the IP address. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 25. In this case, we are talking about a classless subnetted class A address. Network 10 split into subnets similar to a class C. However, in all cases here, the host portion of the address, the fourth byte is all 0s and that represents that subnet or network itself. In other words, these are destination networks or subnets. In the case of remote destinations, the routing table entries show what the next hop is in order to reach that destination. In this case, in order to reach 10.1.3.0, our next-hop is router 2 at 10.1.2.2. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 26. These are categories of routing table entries that could be populated either dynamically or statically. Some of them are born with the router. As soon as the router boots up, it will identify its directly connected active networks and interfaces and define them as reachable destinations, only because of the fact that the router is directly attached or connected to it. Now that is pretty smart, but even smarter is the fact that the routers will communicate with each other, exchange routing information via dynamic routing protocols like OSPF or EIGRP, and then learn not only about those destinations, but also adjust to changes on those destinations. Routing protocols will be able to identify topology changes and tell each other about them. Soon enough, entries will appear and disappear from the routing table according to availability; again, an administrator could come in and manually insert static entries. This is sometimes not recommended because they will be static and they will not adjust to network changes; in other words, if the entry or the destination goes down, the entry will remain there and the router will still forward packets to a destination that is not available. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 27. Perhaps a special case of a static route is the default route. Although they can also be learned dynamically, static defaults are used when no explicit route to a destination is known and so this is the entry that identifies all unknown destinations. The router will say, "If I do not know about a certain destination, I will forward a packet to someone that does, typically another router. Routing Metrics Optimal path selection depends on what is known as the cost to reach a destination across a certain path. Again, the cost of a path is made up of incremental costs for each hop along the path. The cost is also known as metric, and different routing protocols will consider different criteria in order to define the metric. Older technologies and protocols consider the number of routers along the path in order to reach a destination; that is what they call the hop count. Hop count is sometimes not an efficient way to determine cost, because you could have different bandwidths associated with each hop or each link. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 28. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Router Cost Path Factors Establishing Internet Connectivity 29. In this example the two-hop path is better, because it has more bandwidth available. Other routing protocols start considering bandwidth as a measure of cost, and even more parameters in the criteria, for example, EIGRP considers bandwidth delay, reliability, load, and maximum transmission unit. In that case, a path with enough bandwidth, but one that is fully congested, would not be selected and perhaps another path with less available bandwidth would be selected because it is less congested and more reliable. Perhaps one of the points and highlights of this lesson is the fact that routing protocol selection, if you are doing dynamic routing, is key in determining the cost or metric and, therefore, how efficient and optimal the path selection will be, but also the convergence time, which is defined by the time it takes for routing protocol to detect a topology change and adjust by selecting an alternative path if the main path is down. There are different categories of routing protocols if you are using dynamic routing that define their cost and metric, but also their behavior under those circumstances. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 30. Distance Vector Routing Protocols Perhaps one of the points and highlights of this lesson is the fact that routing protocol selection, if you are doing dynamic routing, is key in determining the cost or metric and, therefore, how efficient and optimal the path selection will be, but also the convergence time, which is defined by the time it takes for routing protocol to detect a topology change and adjust by selecting an alternative path if the main path is down. There are different categories of routing protocols if you are using dynamic routing that define their cost and metric, but also their behavior under those circumstances. Using the distance vector approach, which is one of the categories, routers do not have to really know the whole path toward the destination. They only have to know the direction or vector in which to send a packet. In that sense, it will only keep information in the routing tables related to what the next-hop should be in order to reach a certain destination. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 31. Link-State Routing Protocols Link-State protocols are more efficient and effective in creating network topologies, sharing them, and selecting the best path as compared to distance vector protocols. There are several differences between the two categories. For example, link state protocols will not broadcast the information per router, it will use multicast where each router advertises via that multicast the link it knows to the neighbors. Secondly, link-state protocols do not advertise periodically. After an initial flood of all the information, yet will only advertise changes to the topology. In other words, if the link goes down then that small change will be advertised via multicast. Third, router not only know about the next hop toward a destination, they know about the whole topological map of the network. Each router after the initial flood will build that map of the network, which includes all the routers and all the links. With that information, each router is capable of browsing those tables via using the shortest path first algorithm, and select the best path toward each destination. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 32. Configuring a Cisco Router Here i will provide you some basic commands to set up your router . More details on each topic will be coming in following lessons. The Cisco IOS software provides access to several different command modes. Each command mode provides a different group of related commands. For security purposes, the Cisco IOS software provides two levels of access to commands: user and privileged. The unprivileged user mode is called user EXEC mode. The privileged mode is called privileged EXEC mode and requires a password. The commands available in user EXEC mode are a subset of the commands available in privileged EXEC mode. The following table in the next slides describes some of the most commonly used modes, how to enter the modes, and the resulting prompts. The prompt helps you identify which mode you are in and, therefore, which commands are available to you 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 33. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity Cisco Router Mode 34. User EXEC Mode: When you are connected to the router, you are started in user EXEC mode. The user EXEC commands are a subset of the privileged EXEC commands. Privileged EXEC Mode: Privileged commands include the following: Configure Changes the software configuration. Debug Display process and hardware event messages. Setup Enter configuration information at the prompts. Enter the command disable to exit from the privileged EXEC mode and return to user EXEC mode. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 35. Configuration Mode Configuration mode has a set of sub modes that you use for modifying interface settings, routing protocol settings, line settings, and so forth. Use caution with configuration mode because all changes you enter take effect immediately. To enter configuration mode, enter the command configure terminal and exit by pressing Ctrl-Z Getting Help In any command mode, you can get a list of available commands by entering a question mark (?). Router>? To obtain a list of commands that begin with a particular character sequence, type in those characters followed immediately by the question mark (?). Router#co? configure connect copy 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 36. To list keywords or arguments, enter a question mark in place of a keyword or argument. Include a space before the question mark. Router#configure ? memory Configure from NV memory network Configure from a TFTP network host terminal Configure from the terminal You can also abbreviate commands and keywords by entering just enough characters to make the command unique from other commands. For example, you can abbreviate the show command to sh. Configuration Files Any time you make changes to the router configuration, you must save the changes to memory because if you do not they will be lost if there is a system reload or power outage. There are two types of configuration files: the running (current operating) configuration and the startup configuration. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 37. Use the following privileged mode commands to work with configuration files. configure terminal modify the running configuration manually from the terminal. show running-config display the running configuration. show startup-config display the startup configuration. copy running-config startup-config copy the running configuration to the startup configuration. copy startup-config running-config copy the startup configuration to the running configuration. erase startup-config erase the startup-configuration in NVRAM. copy tftp running-config load a configuration file stored on a Trivial File Transfer Protocol (TFTP) server into the running configuration. copy running-config tftp store the running configuration on a TFTP server. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 38. IP Address Configuration Take the following steps to configure the IP address of an interface. Step 1: Enter privileged EXEC mode: Router>enable password Step 2: Enter the configure terminal command to enter global configuration mode. Router#config terminal Step 3: Enter the interface type slot/port (for Cisco 7000 series) or interface type port (for Cisco 2500 series) to enter the interface configuration mode. Example: Router (config)#interface ethernet 0/1 Step 4: Enter the IP address and subnet mask of the interface using the ip address ipaddress subnetmask command. Example, Router (config-if)#ip address 192.168.10.1 255.255.255.0 Step 5: Exit the configuration mode by pressing Ctrl-Z Router(config-if)#[Ctrl-Z] 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 39. Here is an example of configuring a serial port with an IP address: switchA#config switchA (config)#interface serial 1/1 switchA (config-if)#ip address 192.168.155.2 255.255.255.0 switchA (config-if)#ipv6 address fe80::230:1bff:fe80:b8ea/64 switchA (config-if)#ipv6 enable switchA (config-if)#no shutdown switchA (config-if)#ctrl-Z Then to verify configuration: switchA #show interface serial 1 In the Cisco IOS, the way to reverse or delete the results of any command is to simply put no in front of it. For instance, if we wanted to unassign the IP address we had assigned to interface serial 1/1: switchA(config)#interface serail 1/1 switchA (config-if)#no ip address 192.168.155.2 255.255.255.0 switchA(config-if)ctrl-Z switchA #show interface serial 1/1 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 40. To create a static route, the administrator tells the router operating system that any network traffic destined for a specified network layer address should be forwarded to a similiarly specified network layer address. In the Cisco IOS this is done with the ip route and ipv6 route commands. switchA #config switchA(config)#ip route 172.16.0.0 255.255.255.0 192.168.150.1 switchA(config)#ctrl-Z switchA #show ip route switchA #config switchA(config)#ipv6 route fe80::230:1bff:fe80::/64 fe80::230:1bff:fe80::1 switchA(config)#ctrl-Z switchA #show ipv6 route 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 41. Routing Protocol Configuration Routing Information Protocol (RIP) Step 1: Enter privileged EXEC mode: Router>enable password Step 2: Enter the configure terminal command to enter global configuration mode. Router#config terminal Step 3: Enter the router rip command Router(config)#router rip Step 4: Add the network number to use RIP and repeat this step for all the numbers. Router(config-router)#network network-number Example: Router(config-router)#network 192.168.10.0 To turn off RIP, use the no router rip command. Router(config)#no router rip 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 42. Other useful commands Specify a RIP Version By default, the software receives RIP version 1 and version 2 packets, but sends only version 1 packets. To control which RIP version an interface sends, use one of the following commands in interface configuration mode: 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 43. To control how packets received from an interface are processed, use one of the following commands: 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Enable or Disable Split Horizon Use one of the following commands in interface configuration mode: Establishing Internet Connectivity 44. Open Shortest Path First (OSPF) Step 1: Enter privileged EXEC mode: Router>enable password Step 2: Enter the configure terminal command to enter global configuration mode. Router#config terminal Step 3: Enter the router ospf command and follow by the process-id. Router(config)#router ospf process-id Pick the process-id which is not being used. To determine what ids are being used, issue the show process command. Router(config)#show process Step 4: Add the network number, mask and area-id Router(config-router)#network network-number mask area area-id The network-number identifies the network using OSPF. The mask tells which bits to use from the network-number, and the area-id is used for determining areas in an OSPF configuration. Example: Router(config-router)#network 192.168.10.0 255.255.255.0 area 0.0.0.0 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 45. Repeat this step for all the network numbers. To turn off OSPF, use the following command. Router(config)#no router ospf process-id Configure OSPF Interface Parameters You are not required to alter any of these parameters, but some interface parameters must be consistent across all routers in an attached network. In interface configuration mode, specify any of the following: 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 46. Interior Gateway Routing Protocol (IGRP) Create the IGRP Routing Process To create the IGRP routing process, use the following required commands starting in global configuration mode:- 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Disable Holddown The holddown mechanism is used to help avoid routing loop in the network, but has the effect of increasing the topology convergence time. To disable holddowns with IGRP, use the following command in router configuration mode. All devices in an IGRP autonomous system must be consistent in their use of holddowns. Commands: No metric holddown Establishing Internet Connectivity 47. Enforce a Maximum Network Diameter Define a maximum diameter to the IGRP network. Routes whose hop counts exceed this diameter are not advertised. The default maximum diameter is 100 hops. The maximum diameter is 255 hops. Use the following command in router configuration mode. metric maximum-hops hops To turn off IGRP, use the following command- Router(config)#no router igrp autonomous-system Border Gateway Protocol (BGP) Enable BGP Routing Use the following commands in global configuration mode. router bgp autonomoussystem ---- Enable a BGP routing process, which places you in router configuration mode. network network-number[mask network-mask] [routemap route-map-name] Flag network as local to this autonomous system and enter it to the BGP table. 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 48. Configure BGP Neighbors BGP must completely understand the relationships it has with its neighbors. Command: neighbor{ip-address | peergroup-name}remote-as number -- Specify a BGP neighbour. Reset BGP Connections Use either of the following commands in EXEC mode to reset BGP connections clear ip bgp address -- Reset a particular BGP connection. clear ip bgp *-- Reset all BGP connections. To turn off BGP, use the following command. Router(config)#no router bgp autonomous-system 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity 49. Lessons Learned: TCP/IP Protocol Structure Subnetting Functions of Router Configuring Cisco Router 8/2/2013 Instructional Design-Computer Networking - Bridges Educational Group Establishing Internet Connectivity