Ping S7700 gateway the delay is big, but ping the equipment hang in other ports the delay is small.
1、When ping the equipment hang in S7700’s other ports, as the data is transferred by hardware, the transfer speed is very rapidly, so the delay is small.
2、 When ping the gateway of S7700, the ICMP massage need to be disposed by S7700’s CPU, so the delay is big. Reasons as follows:
1)In order to prevent the equipment from the ping attack common in the network, S7700 sets the priority of ICMP message processing to the lowest.
2)S7700 system is a distributed processing system, ARP, ICMP and routing information are processed by main control board, so the ICMP message do ping operation beam from business board to main control board. After processing is complete, it will be returned to the business board. And because the ICMP message priority is low, it is at the bottom of the list in message transmission and processing, so time delay will be bigger.
Though the time delay is big when ping the gateway of S7700, as the business data message need not to be processed by CPU but processed by the bottom chip, so the data packet transfer speed will not be in influenced.
In order to solve the problem that the time delay of S7700 gateway is big, the S7700 business board will response ICMP directly when received ICMP packets, so the CPU processing speed to ICMP message will be promoted.