Case Study

Total Access 5000

Dynamic Bandwidth Allocation over a Legacy DLC

The ADTRAN® Total Access® 5000 is a carrier class IP Multiservice Access Platform enabling service providers to evolve to an IP/Ethernet network model while preserving legacy investments. The Total Access 5000 is designed around a pure IP/Ethernet core that offers unparalleled bandwidth to each subscriber. The backplane architecture provides a fully redundant, dedicated, dual star bus to each individual slot, supporting up to 10 Gbps of non-blocking redundant throughput. This bandwidth scalability per slot ensures a long product lifecycle and long-term investment protection as bandwidth demands continue to increase.

BackgroundAlthough the emergence of next-generation services is driving fiber deployment deeper into the network, there are still many areas where the deployment of fiber is impractical. The Total Access 5000 supports both a T1 Line Module and an HDSL4 Line Module which provide copper transport alternatives for the Total Access 5000 Multiservice Access and Aggregation Platform. The T1 and HDSL4 Line Modules allow carriers to deploy a more cost-effective IP/Ethernet core product in the network, leveraging existing copper transport facilities until fiber can be economically deployed to that location.

Traditional copper-fed Remote Terminals (RTs) have required separate TDM DS1s for voice transport and ATM DS1s for data transport. The Total Access 5000 T1 and HDSL4 Line Modules leverage IEEE 802.3ah Ethernet in the First Mile (EFM) to bond DS1s together to create a converged Ethernet over copper transport infrastructure that carries both data and voice traffic. EFM bonding allows DS1s to be dynamically added or subtracted (due to unlikely span failures), providing redundancy with sub 50 ms failover times to support critical traffic. Additionally, T1 Line Modules or HDSL4 Line Modules can be deployed in adjacent slots, providing 1+1 equipment redundancy. T1 or HDSL4 ports can be bonded together across the adjacent slots, allowing for up to 16 bonded T1s (or 16 bonded HDSL4s) or 24 Mbps of Ethernet transport bandwidth over copper.

Case Study

Case StudyBandwidth across the EFM links is managed dynamically and prioritized via 802.1p. Additionally, since calls are dynamically set up in the Total Access® 5000 only when the line is active, lower priority data traffic can leverage previously unused POTS bandwidth, allowing carriers to offer higher bandwidth and higher revenue services even in copper fed locations.

ChallengeTraditional copper-fed remote terminals are engineered with separate sets of TDM DS1s for voice transport and ATM DS1s for data transport. The ATM DS1s are typically engineered based off an oversubscription ratio, such as 24 customers per DS1, and a minimum number of DS1s required to provide a service. For example, to provide a 3 Mbps ADSL service, at least 3 DS1s are required, since the ATM DS1s are bonded together using IMA, which means only ~80% of the bandwidth (or 3.6 Mbps) will be available for customer use.

When engineering TDM DS1s for voice transport, it is standard to engineer a DLC for approximately 4 CCS per customer with a Grade of Service (GOS) between .001 and .01. A .001 GOS means that 0.1% of calls may be blocked. Using Erlang B tables, this equates to approximately 22 trunks (or 1 T1) required back to the switch for every 96 customers, or a 4:1 oversubscription ratio.

As the Total Access 5000’s copper (T1 or HDSL4) Line Modules bond DS1s together with EFM to carry both data and voice traffic, bandwidth is shared over a single set of DS1s. With EFM bonding and voice traffic being transported dynamically over the DS1s, new engineering practices are required to determine how many DS1s are required from Remote Terminal (RT) back to the Central Office Terminal (COT).

Total Access 5000Dynamic Bandwidth allocation over a Legacy DLC

Case StudySolutionThe first step in engineering dynamic copper bandwidth is to determine the amount of bandwidth required for data. Data traffic uses significantly more bandwidth and therefore it will require more bandwidth than voice traffic. We can start with the same engineering practices for data as would be used in a traditional copper-fed remote terminal, however there will actually be more bandwidth as EFM bonding only uses 1-5% overhead, while IMA overhead is ~12%. See Table 1 on next page.

With the Total Access 5000, to engineer for voice with data, additional DS1s can be added to the EFM group to support voice traffic. A minimal number of DS1s is needed though, as voice traffic that exceeds this addi-tional bandwidth will not be blocked, but will rather be carried on the bandwidth that is otherwise used for data. Therefore, instead of engineering DS1 capacity for voice traffic based on a maximum call load, it can instead be engineered based off an average call load. Using the same basis for engineering as in the legacy DLC, and the fact that a Total Access 5000’s packetized voice uses approxi-mately 90 kbps per call instead of 64 kbps, a single T1 is now only added for every 205 customers!

This equates to significant savings in both capital and expense, as an average T1 costs approximately $2000 in capital on T1 setup costs.

ResultsCapital savings add up significantly as ports are added to a Remote, as may be seen in Tables 2 and 3 on the following pages.

$6,000

$7,000

24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456

$5,000

$4,000

$3,000

$2,000

$1,000

$-

# POTS ports with 50% equipped for DSL

Savings on T1 Setup Costs

Table 1

Table 2

18

20

24 48 72 96 120 144 168 192 216 240 264 288 312 336 360 384 408 432 456

Mbps

16

14

12

10

8

6

4

2

0

# POTS ports with 50% equipped for DSL

Legacy DLC

ADTRAN Total Access 5000 BBDLC

Bandwidth Available for Data

Case Study

The Total Access® 5000 allows service providers to take advantage of operational benefits of EFM bonding and packetized voice. With capital savings of between $10 and $20 per port from the T1/HDSL4 circuit setup costs, there are considerable savings to be realized. A service provider will realize additional operational savings with less circuits to maintain, as well as being able to use the additional available copper for future growth.

ADTRAN’s Total Access 5000 is one component of an industry leading family of access and transport solutions that ubiquitously support multiple network topologies, reducing unwanted operational complexity and maximiz-ing network efficiency. ADTRAN’s Total Access 5000 is the right choice for next generation Broadband Loop Carrier deployments.

Total Access 5000Dynamic Bandwidth allocation over a Legacy DLC

Case Study

CN041A Copyright © 2009 ADTRAN, Inc. ADTRAN believes the information in this publication to be accurate as of publication date, and is not responsible for error. Specifications subject to change without notice. ADTRAN and Total Access are registered trademarks of ADTRAN, Inc. and its affiliates in the U.S. and certain other countries.

These savings equate to between $10-20 per port in capital savings

$80

$90

24 96 168 240 312 384 456 528 600 672 744 816 888 960 1032 1104 1176 1248 1320

$70

$60

$50

$40

$30

$-

# POTS ports with 50% equipped for DSL

Savings on a Per Port BasisSavings Per Port

$20

$10

Table 3