Networking with Wireless and LAN technology Part Two
For the real-time transaction server (which provides the system used to ensure funds are available at the cash desks), all records are held and accessed centrally in the Cyncoed office. All branches connect to this main server for any transaction, the current arrangement is likely to be inadequate considering the new customers coming to the building society. Currently the server processes around 100 customers a day, this will double with the opening of the new branches. Each customer requires 5 megabytes (total) of upload and download to ensure payment is available. CBBS currently has an agreement on a private line providing 1Gbyte of bandwidth a day with a download/upload speed of 2Mbps – each transaction takes about 20 seconds to complete – CBBS finds this 20 seconds unacceptable and would like the processing time to be no more than 10 seconds. You will need to suggest a new bandwidth allocation and speed allocation for the real-time transaction server.
Consider this to understand what actually is it that’s going to go down when customers & bandwidth is doubled: Delay is pertinent for every data transmission expertise but particularly aimed at satellite links as well as elongated terrestrial cables. Satellites orbiting our planet at height of almost 36,000 km. This extensive remoteness hints to a propagation delay of almost 270 ms for a worldwide satellite hop. When it comes to the network of elongated terrestrial cables propagation delay is about 1 ms for every 200 kilometers (120 miles). This type of delay would be ideal for the scenario. Some might argue that a serialization delay can also be idyllic as the time to put digital data onto a transmission line, which depends on the data volume and the speed of the line. For example, to transmit a 1024-byte packet on a 1.544-Mbps T1 line takes about 5 ms. But in view of a user and a network designer first scenario is ideal as it deals with elongated terrestrial cables propagation network.
Now turning to technicalities involved: Unlike the first network configuration wherever every GT was allotted a hard and fast portion of the information measure, multiple GTs area unit currently in competition to get information measure. We tend to thus want the simplest way to share the overall obtainable information measure between multiple requesters. The supposed satellite’s multiple access techniques being a mix of frequency division multiple access (FDMA) and time division multiple access (TDMA), we tend to use the thought of a frame to represent a knowledge burst an information measure allocation.
A consequence of the primary modification is that the truth we tend to cannot let informatics management the transmission of the packets for it might use all the obtainable information measure while not relevancy a GT’s allocation. The last modification to the network model is that the addition of a node answerable for information measure allocation. This node, referred to as the master controller (MC), allocates parts of the overall obtainable information measure (frames) to the GTs consistent with the information measure requests received. There’s one megacycle per second per satellite beam that has satellite communication links to any or all GTs under its beam. Those links, used for the exchange of access management info, area unit break free the information measure obtainable for knowledge transfer.
The information measure allocation theme aims at rising the performance of the applications that use the satellite links and therefore the information measure utilization i.e. turnout of these links. Our answer drives at this goal by allocating information measure as the performance of the GTS desires that are calculable in step with the extent and kind of traffic they\’re experiencing. Compared to static allocation, this technique contains a major advantage that improves each information measure utilization of the satellite links and therefore the performance of the applications. Once causing an information measure request to the MHz, a GT can offer info regarding the present size i.e. a variety of packets and weights of its queues. As we are going to see shortly, this info can confirm the quantity of information measure allotted to the GT.
Ground control functionality: The dynamic information measure allocation is supported during a GT by a processor known as satellite medium access controller (SatMAC). The SatMAC is accountable of handling the transmission of packets on the satellite link and requesting/receiving information measure allocations from the mc. Link layer characteristics, like modulation and burst time plans, don\’t seem to be taken into consideration additionally, to change our model, the reception of information packets from the opposite GTS is performed directly by informatics since the SatMAC doesn’t act on those packets.
Master controller functionality: The MHz is that the central purpose of management for information measure allocation during a beam. it\’s answerable for receiving information measure requests from the GTS within the beam and responding to those requests with information measure allocations.
In choosing a VPN technology, it\’s necessary to think about body problems. Giant networks have to be compelled to store per-user directory info in an exceedingly centralized knowledge store, or directory service, so directors and applications will increase, modify, or question this info. Every access or tunnel server might maintain its own internal knowledge base of per-user properties, like names, passwords, and dial-in permission attributes. However, as a result of it\’s administratively prohibitory to take care of multiple user accounts on multiple servers and keep them at the same time current, most directors originated a master account info at the directory server or primary domain controller.
The Routing and Remote Access service is each a dial-up remote access server and VPN server for PPTP and L2TP connections. Consequently, these Layer two VPN solutions inherit all of the management infrastructure already in situ for dial-up networking.
In Windows 2000, the Routing and Remote Access service take advantage of the new Active Directory, An enterprise-wide, replicated info supported the light-weight Directory Access Protocol (LDAP). LDAP is an industry-standard protocol for accessing directory services and was developed as an easier various to the X.500 DAP protocol. LDAP is protractile, vendor-independent, and standards-based. This integration with the Active Directory permits an administrator to assign a range of affiliation properties for dial-up or VPN sessions to individual users or teams.
Redundancy and cargo reconciliation is accomplished victimization round-robin DNS to separate requests among a variety of VPN tunnel servers that share a standard security perimeter. A security perimeter has one external DNS name-for example, microsoft.com-but many information processing addresses, and hundreds area unit haphazardly distributed across all of the information processing addresses. All servers will attest access requests against a shared info, like a Windows domain controller. Windows domain databases area unit replicated between domain controllers.
Top-Down Network Design, Third Edition by Priscilla Oppenheimer, Cisco Press.
- Iera, A. Molinaro, G. Aloi, S. Marano, “Dynamic Channel Access Protocol in Geo-synchronous Satellite Networks”, Proc. Wireless Communications and Networking Conference, pp 813-817, September 2000
Planning a Network Upgrade by John Iglesias, Hardman University Press.