Topology: L3---MA5200F---Lanswitch---Cyber User
Phenomenon Description: MA5200F has speed limit (3M, 10M) on static users. Lanswitch is S2403H-EI and user port is configured as 10M duplex. The interconnection of Lanswitch and MA5200F is self-negotiation. Part of users use broadband of 10M CAR and the speed is only about 200-300KB/s. Part of users use broadband of 3M CAR and it is normal at the speed of 300KB/s.
Configure interconnection of switch and user as self-negotiation or 100M full-duplex. The downloading speed of users with 10M CAR can reach 1.1MB/s and The downloading speed of users with 3M CAR can reach350KB/s. It is not problematic.
Enable 10M CAR at MA5200F and limit user's average broadband as 10M. Burst bandwidth must be configured and it is often five times of average value. Configure layer 2 switch and connected port of user with 10M full-duplex and limit the maximum bandwidth as 10M. It will happen to burst traffic over 10Mbit/s. The bandwidth of switch is only 10M and surpassed part will be discarded. Discarding packets will cause TCP sliding window zoom out, so downloading speed is slow. For users of 3M CAR, 10M bandwidth can meet demands of burst traffic (three times of average one) and it is normal.
Enable CAR limit; ensure physical bandwidth of downlink equipment is 3-5 times of average CAR speed. If physical port is too small and burst traffic cannot pass, it will influence downloading speed.