Help!!!Slow download on a 100Mbps link

[Minue]

Hello All
We have an issue with a customer that has purchased a 100Mbps link (guaranteed) to the Internet.This customer then resells Internet services to his clients.He's complaining that when the link has low usage he can download at 30Mbps from our test server.But in the busy moments of the day when his clients are using about 50 to 60Mbps of the bandwith,he can only download from our test server at 1Mbps.His logic is that he stills has 40Mbps left, so he should be getting a higher download rate even when the link is partially congested.
Any input would be greatly appreciated.

Thanks a million in advance

 

[VinceWhirlwind]

Try increasing the TCP/IP window size at both ends - perhaps it's the increased latency and a small TCP/IP window that's causing it, not a lack of bandwidth?

 

[ISPKing]

There is absolutely no info here? What kind of connection, routers, switches etc>?

CCNP

 

[Minue]

Hello
Thanks guys for the replied.Vince the customer wouldn't accept this as a solution,he just needs his bandwith without any tweaking.
ISPking ,sorry for the lack of info,our edge router is a 6509 with a pretty recent supervisor,it's doing MPLS VPN for interconnection between customer sites.EIGRP for VOIP and Static routing for Internet access.We are terminating about 150 clients.The customer is running a 3825 router with a Fiber line, and a static routing point to us.Behind this router he obviously has another router running BGP in Multihop with our Internet routers.
Could it be that after a router is getting close to full regime,it become harder to get more out of it.Like with a car at top speed and trying to get those last few miles out of it.
Regards

 

[ISPKing]

Well i can tell you that the 6509 is probably in good shape. We push over 300 Routed mpbs on a sup II at one of our sites.
The 3825 i would take a look at.

CCNP