This is a multi site network. Site A has a Cisco 3825 router and connects to 3 other sites over ISP A and 2 other sites over ISP B. Both ISP A & B provide a layer 2 full mesh network. ISP A provides a 100mb pipe while ISP B provides a 20mb pipe.
File transfers (Windows - CIFS) over ISP A's fiber are fast enough and throughput is good. However, file transfers (Windows - CIFS) over ISP B's fiber are slow, even though latency is good.
On the 100MB ISP A pipe, file transfer speeds upto 6 MBps are achieved. On the ISP B 20MB pipe, speeds upto 300KBps are seen for file transfers.
ISP A connects to an on board gig port on the 3825. ISP B connects to a fastethernet port on an HWIC-2FE card on the same 3825. Both ports then connect to ISP Switches and then full meshed to remote site Cisco routers.
What could be the issue? Why am I facing these issues only with ISP B even though the configs for ISP A and ISP B are the same?