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Traditionally, a DSL customer's synch rate was provisioned directly on the DSLAM and hard set to a specific profile. A customer with a 768/128Kbps service would synch at 768/128Kbps between the DSLAM and the modem, regardless of the overall attainable line rate possible. MaxSync introduces two important differences.
1. The synch rate is no longer provisioned on the DSLAM. The DSLAM and modem will synch at the highest rate possible (within certain criteria).
2. Service speed is controlled via a RADIUS profile. So the customer mentioned above with 256/128 service may see a 8128/512 synch rate if they were changed to a MaxSync profile depending on their individual line conditions, but only get 768/128 throughput to the Internet.

The good news
Changes in service levels can be done without reprovisioning the DSLAM and accomplished with just a simple RADIUS change. It enables the possibility of offering bandwidth on demand service in the future. It also gives the customer and BellSouth the ability to see the overall condition/capability of the customer's loop. If a customers line can only MaxSync at 3552/384 they would not be a good candidate for the 6000/512 service. Conversely, a customer currently on 768/128 that MaxSyncs at 8128/512 shouldn't have any problems upgrading to 3000/384.

The bad news
Generally, higher bandwidth lowers the overall signal to noise margin and increases line attenuation. The MaxSync profile could create problems for a customer that were never an issue before. For example:

1472/256 service with traditional provisioning at the DSLAM
- Marginal line with attainable line rate of 3600/500
- Signal to noise margin of 10dB
- Line attenuation of 55dB
- Loop Capacity is about 41%
The customer has never had any problems even though the line is marginal because of the low synch rate.

Same 1472/256 service set to MaxSync profile
- Marginal line attainable line rate of 3600/500
- MaxSynch rate of 3552/384 (possibly with interleaving)
- Signal to noise margin of 6dB
- Line attenuation of 60dB
- Loop Capacity is almost 100%
The customer will probably experience constant connectivity issues and will be placed on an interleaved profile. Although newer interleaving techniques have reduced the overall latency as compared to older methods, it still introduces some latency.

How can I tell If I'm on MaxSync?
A simple way to tell if you are on MaxSync is to check your synch rate and modem stats. If your synch rate is far above your actual service plan, chances are you are on MaxSync. The highest sync rate is approximately 8128/512Kbps.

Important Information:
Due to differences in network topology, MaxSync is not available to all FastAccess customers. Additionally, just because you have been put on a MaxSync profile does not mean you are automatically eligible for all tiers of service!

Ultra-Mega, Don't Pass This Up Important Information:
Don't call the help desk and ask to have Interleaving removed. Fix the issue that is responsible for the problem that led to being put on interleave. You may be able to fix the problem yourself or it may take a truck roll. Regardless, fix the problem first!

Additional Information:
How do I check modem statistics? What do the numbers mean and are my stats good?
What is Interleaving and Fastpath?

Andy Houtz DSL

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by FAQFixer See Profile
last modified: 2009-07-11 22:58:11