Assessments - 2, GPA: 3
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In the case of the TCP/IP protocol suite, the OfficeConnect Remote utilizes the Routing Information Protocol (RIP). RIP is also known as a distance vector protocol. Different protocols use differing network characteristics or metrics when making routing decisions. The metric employed by RIP is a Hop Count. A hop count is defined by the number of routing nodes there are between the source and destination units. In our example, there are two hops between LAN1 and LAN 2 going via Routers A and B. If traffic was directed via Routers A, D, and then B, this would be three hops. The algorithm will automatically select to forward the data packet via Router A, as this route contains the least number of hop counts which makes it the preferred direct route. Every thirty seconds, each IP router will advertise via RIP datagrams, to all other routers on the internetwork, how many hops it takes to reach all connected logical networks, based on the routers network position and the state of its physical links. In an ISDN environment, making ISDN calls every thirty seconds to pass on and receive RIP updates would be costly. When initially setting up network, the OfficeConnect Remote is manually connected over the ISDN for a three minute period, in order to learn the topology of the rest network. Once this has the OfficeConnect Remote will only make ISDN calls to transmit data packets. While this data transfer is in progress, RIP updates will be piggybacked on to the call, updating both parts of the network with the latest RIP information. It is also possible to assign what are known as static routes, which are manually entered fixed routes. The network manager may be aware of specific traffic patterns, or needs to enforce a particular routing policy. Static routes provide an option to force traffic through the network in a particular way. The disadvantage with this approach is that routing protocols dynamically update all the routers on the network, with the current network topology, enabling backup routes to be deployed. In a static route situation, if the WAN links in that routing definition are down, then traffic cannot be passed. Implementing a static route prohibits the router from being able to offer alternative data paths. IPX Routing Novell IPX also uses RIP for routing purposes. Although it is similarly named to the IP equivalent, it uses a different protocol. IPX RIP broadcasts datagrams out onto the network every sixty seconds. Upon receipt of a RIP datagram, a router adds one to the hop count of each route advertised and broadcasts a RIP datagram to the other networks, with which it is connected. The cost of a route in an IPX network is determined by the metric known as ticks. In a LAN only environment this is the hop count plus one, e.g. three hops or four ticks. For an internetwork connected via a WAN or ISDN links, the tick count is factored on the speed of the WAN link. We saw above the common network numbering scheme employed for a bridged network. By employing routing, LAN A, LAN B and LAN C become three separate networks on a network. The network numbering must reflect that situation. In a Novell IPX environment we could allocate IPX network numbers 00000111 A, 00000222 to LAN B and 00000333 LAN C. Having configured Routing IP and IPX A-11 the ports of the OfficeConnect Remote to accept this protocol, routing will now occur between the remote network servers and workstations but addressed by different network numbers. It should be noted that NetWare 3.X and later, uses the concept of internal IPX addresses, which is somewhat similar to network addressing. The internal address refers to the internal network within that server allowing internal processes to communicate. These numbers must be unique for all servers right across the network. Although network servers may appeared wired correctly, and in other respects seem to be working correctly, duplicated internal IPX addresses will not allow correct operation. NetWare has a hop count limitation imposed by the RIP. On an IPX network a data packet can cross a maximum of fifteen routers before being discarded. IP Addresses TCP/IP Numbering and subnet masking IP numbers or addresses are normally made up of four fields (normally called bytes), with each byte having a whole number value of between 0 and 255, and the bytes separated by a full stop. For example: 123.123.123.123 An IP address is divided into two sections, one is the Network Address section and the other is the Host Address section. For example: 123.123.|123.123 Network Host The divider | between the two sections is moveable according to what class of IP address it is. The class of address is defined by what the number is in the first address byte: ¦ For a Class A IP address the number will be in the range 00 to 126 ¦ For a Class B IP address the numbers in the second bytes will be in the range 128.001 to 191.254 ¦ For a Class C IP address the numbers in the first, second & third bytes will be in the...
Este manual também é adequado para os modelos :Controle remoto - 520 (1.34 mb)
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