RFC792 ICMP协议（国外英文资料）.doc

RFC792 ICMP协议（国外英文资料） Network Working Group j. Postel Request for Comments: 792 ISI September 1981, Updates: RFCs 777, 760 Updates: IENs 109, 128 Rfc792-internet control information protocol (ICMP) (RFC792 INTERNET CONTROL MESSAGE PROTOCOL) directory 1. Introduction 2 Message format 2 Aim for information 3 Timeout information 3 The parameter problem message 4 Source congestion message 5 Redirect message 6 Return or return response message 7 Timestamp and timestamp response message 8 The message type summarizes 9 See resources 10 1. Introduction In a system called Catenet, the IP protocol is used as a data service for hosts to the host. Network connection devices are called gateways. These gateways are exchanged for control information through gateways to the gateway protocol (GGP). Typically, the gateway or destination host communicates with the source host, for example, to report errors in the datagram process. For this purpose the ICMP is used, it USES IP as the underlying support, as if it were a high-level agreement, but in fact it is part of the IP, each IP module must implement the ICMP. ICMP message sent in the following cases: when datagrams cannot reach the destination, when the gateway has lost the cache function, when the gateway can guide the host on the more short circuit by sending. IP is not designed to absolutely reliable, the purpose of this agreement is to return to control information, when network problems rather than make IP protocol is absolutely reliable, does not guarantee a datagram or control information to return. Some reports will still be lost without any reports. The upper layer protocol must use its own error control program to determine if the communication is correct. ICMP information is usually reported to be an error in the processing of the datagram process. If information is not returned indefinitely, the ICMP messages will not be sent separately, and the ICMP information will only be sent when the data report offset is zero. 2.