I've been using LPC1769 for Biometric based "Attendance Recording & Access Control System" . I'm facing problems based on TCPIP for LPC1769. For small-Network,say 'SNW', (<= 20 computers, connected to LAN) TCPIP is working fine, but for large networks,say 'LNW', greater than 20 computers connected to LAN, as well as at 1gbps network, our systems give number of problems as narrated below(based on a site, where 80 or more PCs are connected to LAN),
1> Very high response time for PING(>600 mSec for 'LNW', against <3 mSec for 'SNW') ,
2> Too much 'Request Timeout' for PING, 70%, approx., for 'LNW', against 0.25% for 'SNW' .
3> Connection with remote Client/Server and data transmission is very very inconsistent for 'LNW' .
where as Connection with remote Client/Server and data transmission is very smooth for 'SNW' .
At the same site, our systems do not face any of the above three problems, on Holidays/Lunch Break/Office Break, when no N/W activity goes on for most PCs .
In our circuit, LPC1769 is running at 120 MHz speed, DP83848c is used as PHY-IC, and ethernet section of our circuit is very very in line as per NXP Datasheet and Application Notes.