New Approach for Broadband Backup Link Design. 

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... I NTRODUCTION T YPICAL methodology, of most to use network to implement decisions, link which backup dial backup is not always a clear choice. Each approach has advantages and disadvantages. Some of the more critical tradeoffs include speed of response to failure, reliability of response to failure, call stability, testability, link performance, and ease of implementation. Backup Link is designed to provide an alternate connection in case of a failure in the primary link. The service offers speeds from 2Mbps to 2.5Gbps to the internet. For today’s modern campus, it is crucial that the communication network is always available for the critical applications without any interruption or failure due to the access link. Dial backup is frequently used as a low-cost method to improve network availability. However, care must be taken to ensure that the backup link will be activated whenever it’s needed; otherwise, the availability improvement may be illusory. Nowadays, the famous backup link is ISDN. Unfortunately, this option sometimes did not often provide enough flexibility to meet the campus needs of the entire institution. In our new approach, we use broadband technology as our backup link. VDSL is used as broadband technology in our experiment and VDSL will link up with the primary line network in campus environment. II. R ELATED W ORKS Broadband access networks are mainly based on xDSL (Digital Subscriber Line), cable modem, and Ethernet [4], [9], [12]. DSL technologies can deliver data at multi Mbits/s over the unshielded twisted pairs of the public telephone network (PSTN) [7], [8], [11]. Broadband applications and increasing Internet usage have created a bandwidth demand that super- sedes the capabilities of analog transmission over telephone lines. Use of Digital Subscriber Line (xDSL) technology enables existing telephony infrastructure to deliver broadband services, which is the most robust xDSL technology [1], [2]. Therefore, remote office connectivity and high-bandwidth applications, such as live video on demand and fast Internet access, can now be implemented at minimal cost by using the wholesomeness of Ethernet with the economy of VDSL (Very high bit rate Digital Subscriber Line). Figure 1 shows characteristics and functionality of xDSL families that can be selected for broadband backup link in campus environment. There are two important differences between DSL networks and other access networks. First, like cable networks, DSL networks often have asymmetric bandwidths; their downstream bandwidth is higher than their upstream bandwidth. Second, the maximum data transmission rate falls with increasing dis- tance from the DSLAM [5]. Various protection and restoration schemes have been proposed and investigated to recover traffic when a network failure occurs, e.g., when a fiber link is cut [3], [6], [10]. III. M ETHODOLOGY Figure 2 shows our new approach using broadband backup link design. We have setup a real network environment in University of Kuala Lumpur, Malaysia. We use xDSL technology as our broadband backup link implementation in campus environment. VDSL technology is selected to be linked up with existing primary link. Figure 3 shows the conventional backup link using dial up technology. Dial up technology can be divided into two categories such as modem and ISDN technology. Dial up technology is able to provide low bandwidth and higher error rate. Figure 4 shows the comparison of conventional and broadband backup link technology. We will compare the performance and functionality of bandwidth, utilization, traffic and packet lost. We will demonstrate that broadband technology able to provide better network performance compare to conventional approach. IV. R ESULTS AND A NALYSIS We examine three important characteristics of broadband networks, namely link bandwidths, packet flow, traffic and packet error. Analyzing these properties is important because they affect the performance of protocols and systems running over broadband backup link. We used a network management application to capture traffic flow in back up link real network environment. Figure 5 shows the experimental is used Solarwinds Network management. Figure 5 show that serial interface (primary link) is down and the traffic has routed to xDSL backup link. Network management application has captured packet flow in broadband backup link. The result shows that broadband backup link is able to receive and transmit the packets in vast amount (refer to Fig. 6). Figure 6 shows broadband backup link has transmitted 5000 packet per second (pps). Figure 7 shows average bandwidth measurement on broadband backup link connection. The result shows that this broadband backup link is able to transmit and receive traffic approximately 50 Mbps to 60 Mbps. Therefore, this broadband backup link is able to support higher bandwidth and higher performance compare to conventional backup link. The maximum bandwidth can support by conventional backup link approximately 33 Kbps to 128 Kbps only. Figure 8, proved that broadband (VDSL) backup link technology able to generate higher bandwidth usage from 25 Mbps to 30 Mbps meanwhile the dial up backup link (ISDN) technology only can generate a low bandwidth usage 0.2 Mbps. Therefore, it confirmed that xDSL technology can provide higher bandwidth compared to dial up technology. VDSL is an emerging broadband technology that promises higher data rates over relatively short distances. Therefore, broadband backup link can reduce or eliminate receive and transmit error rate due to higher bandwidth availability provide by broadband backup link (refer to Fig. 9) We show several comparisons of xDSL performances with other technologies such as: 1) xDSL with Dialup technology, 2) xDSL with Cable Modem technology, 3) xDSL with T1 line, 4) xDSL with ISDN technology, in Figs. 10, 11, 12, 13 (see the following pages). Our study characterized several important characteristics of broadband networks, including available link capacities, packet transmission, and packet error. V. C ONCLUSION The fast development of data networks, Internet applications and multimedia capable computers creates a large demand for high-throughput connectivity over the traditional wide area networks. Broadband applications and increasing Internet usage have created a bandwidth demand that replaced the capabilities of analog transmission over telephone lines. This study has developed an alternative approach for broadband backup link as fast development solution in campus network environment and need large demand for high-throughput connectivity. Therefore, the adoption and exciting VDSL technology can provide higher bandwidth demand for backup link. VDSL provides high bandwidth over the existing copper infrastructure that is available to the network operators. Our results demonstrate that our approach achieve better backup capacity utilization and network robustness, compare to a conventional backup link when a network failure occurs. Implementation of xDSL technology is expected to replace the conventional back up link connection today, but it also gives an alternative approach in choosing backup access method for campus network environment ...