Title: routing set incorrectly, resulting in unreasonable network management within MA5100 compiled with code: 0006725 Updated: 2002.04.24 Author: Zhou Yifan audit person: Hu Hao describe the phenomenon: in-band network management on the MA5100 through 8750, not PING pass MA5100 The IP address of the inner network management found that the ping package is too long, and the phenomenon of packet dismissal appears. Alarm Information: ping xxx.xxx.xxx.xxx (MA5100 Band Tube IP) TTL Expired in Transpitttl Expired in Transitttl Expired In Transit Cause Analysis: In the TCP / IP network, the network layer does not perform reliability transmission of packets, Feedback mechanism only by ICMP packets (for example, error control). The ping command is the request / response message of ICMP, and is also the most common test method of the network. Usually use the ping command to test the following message feedback: 1, Request Time OUT2, DESTINATION Unreachable 3, TTL Expired in Transit Case 1: When the source machine PING, the source machine is in a period of time ( After the source machine sends ICMP request packet, the timer 0) will not be able to receive the ICMP response message, which will generate this situation. The reason for the above problem is that the routing of the source to the sink is normal, and the content of the content is not available. Situation 2: This is generated when the source machine is not available to the sinksheet. Situation 3: When the source machine sends an IP packet (ICMP is directly encapsulated in the IP package), the TTL (time to Live) time will be added, the packet will be packaged when a router is passed. The TTL time is reduced. If the TTL of the packet is 0 before the ICMP request message is not until the Schute Machine, the corresponding gateway discards the message, and sends ICMP time-time packets to the source machine. The TTL Expired in Transit message should be displayed on the machine. This problem is mainly, there is a routing loop inside the network that cannot be reached to the sink, using Tracert tracking, determining the fault (preferably when using this command). Note: Some routers are not minus 1 for the TTL time of the package, but the general situation is like this. Method: If normal ping passes a host, you can simply analyze the routing hops passing from the response information IE replay xxx.xxx.xxx.xxx: Byte = xxx Time = xxxms TTL = XXX with 256 minus The value of TTL in this article, that is, the number of routing hops, such as the TTL time is too small, may have a short routing loop in the network. It is easy to appear when configuring static routes, and the dynamic routing protocol is easy to appear, and RIPv2 and OSPF are not easy to appear. Process: 1. Use the tracert command to track the router passed between the target host, and find that the package is looped between two routers; 2. Check the routing table of the problematic router, found that one of the 8750 routing is set The problem, causing the ICMP request message to oscillate between two 8750; 3. If there is a problem with the routing, reconfigure the correct route, and return to normal. Suggestions and Summary: Attachment:
