Experiment-9To Study Types of bridges and routers

A Bridgeis another device used to connect LAN cable segments together. Bridge operates at the data link layer of OSI model.A Bridge provides packet filtering at data link layer, meaning that it only passes the packets that are destinated for the other side of the network.a Bridge has two or more network interface (own MAC address)connected to different cable segments and operating promiscuous mode.Types of Bridges.Three types of Bridges are used in network.1> Transperent Bridge.2> Translational Bridge.3> Source-route Bridge.Transperent Bridge :Transperent Bridges is invisible to the other evices on the network. Transperent Bridge only perform the function of blocking or forwarding data based on MAC address. MAC address may also be referred as hardware address or physical address. These addresses are used to built tables and make decision regarding whether a frame should be forward and where it should be forwarded.Translational Bridge :Translational Bridges are usefull to connect segments running at different speeds or using different protocols such as token Ring and Ethernet networks. Depending onthe direction of travel, a Translational Bridge can add or remove information and fi elds from frame as needed.Source-route Bridge :Source-route Bridges were designed by IBM for use on Token ring networks. the sr Bridge derives the entire route of the frame embedded within the frame. This allows the Bridge to make specific decision about how the frame should be forwarded through the network.Other than above, there are also Local Bridge, Remote Bridge.Local Bridge :A Local Bridge provides paket filtering and repeating services fot the network segments of the same type. this is also called MAC-layer Bridge. This is the simplest type of Bridge because it has no need for packet filtering or buffering. This Bridge simply propagates the incoming packets to the appropriate ports or discard them.Remote Bridge :Remote Bridge connects network segments at different locatios, using WAN link such as MODEM or Leased line. The difference in speed between Local and wide area links, a remote Bridge uses internal buffer to store the data received from LAN while it is waiting for transmission to the remote site.

RoutersA router is used to route data packets between two networks. It reads the information in each packet to tell where it is going. If it is destined for an immediate network it has access to, it will strip the outer packet (IP packet for example), readdress the packet to the proper ethernet address, and transmit it on that network. If it is destined for another network and must be sent to another router, it will re-package the outer packet to be received by the next router and send it to the next router. Routing occurs at the network layer of the OSI model. They can connect networks with different architectures such as Token Ring and Ethernet. Although they can transform information at the data link level, routers cannot transform information from one data format such as TCP/IP to another such as IPX/SPX. Routers do not send broadcast packets or corrupted packets. If the routing table does not indicate the proper address of a packet, the packet is discarded. There are two types of routers:

1. Static routers - Are configured manually and route data packets based on information in a router table.2. Dynamic routers - Use dynamic routing algorithms. There are two types of algorithms: Distance vector - Based on hop count, and periodically broadcasts the routing table to other routers which takes more network bandwidth especially with more routers. RIP uses distance vectoring. Does not work on WANs as well as it does on LANs. Link state - Routing tables are broadcast at startup and then only when they change. The open shortest path first (OSPF) protocol uses the link state routing method to configure routes or distance vector algorithm (DVA).There is a device called a brouter which will function similar to a bridge for network transport protocols that are not routable, and will function as a router for routable protocols. It functions at the network and data link layers of the OSI network model.A router has access to the network layer address or logical address (IP address). It contains a routing table that enables it to make decisions about the route i.e. to determine which of several possible paths between the source and destination is the best for a particular transmission. These routing tables are dynamic and are updated using routing protocols.The routers receive the packets from one connected network and pass them to a second connected network. However, if a received packet contains the address of a node that is on some other network (of which the router is not a member), the router determines which of its connected networks is the best next relay point for that packet. Once the router has identified the best route for a packet to travel, it passes the packet along the appropriate network to another router. That router checks the destination address, find what it considers the best route for the packet and passes it to the destination network.

Types of RoutersThere are several types of routers in the market.Broadband RoutersBroadband routers can do different types of things. Broadband routers can be used to connect computers or to connect to the Internet.If you connect to the internet through phone and using Voice over IP technology (VOIP) then you need broadband router. These are often a special type of modem (ADSL) that will have both Ethernet and phone jacks.Wireless RoutersWireless routers create a wireless signal in your home or office. So, anyPCwithin range of Wireless routers can connect it and use your Internet.In order to secure your Wireless routers, you simply need to come secure it with password or get your IP address. Then, you'll log on into your router with the user ID and passwords will that come with your router.Other Type of RouterEdge RouterThis type of router are placed at the edge of the ISP network, the are normally configured to externalprotocollike BGP (Border gateway protocol) to another BGP of other ISP or large organisation.Subscriber Edge RouterThis type of router belongs toan end user (enterprise) organization. Its configured to broadcast external BGP to its providers AS(s)Inter-provider Border RouterThis type of router is for Interconnecting ISPs, this is a BGP speaking router that maintains BGP sessions with other BGP speaking routers in other providers' ASes.Core RouterA router that resides within the middle or backbone of the LAN network rather than at its periphery. In some instances , a core router provides a stepdown backbone , interconnecting the distribution routers from multiple building of a campus ( LAN), or Large enterprise Location (WAN). They tend to be optimized for a high brandwidth.Wired and Wireless Routers.Home and small office networking is becoming popular by day by the use of IP wired and wireless router.Wired and wireless router are able to maintain routing and configuration information in their routing table. They also provide the service of filtering traffic of incoming and outgoing packets based on IP addresses.Some wireless routers combines the functions of router with those of a network switch and that of a firewall in one.