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The icmp in ipv6
Icmpv6 is the basic support of ipv6. I believe you are already familiar with the ICMP protocol, because in our previous articles we have already introduced icmp error message types of ipv4, However, in the ipv6 what are the differences?
First of all, icmpv6 includes NDP neighbor discovery protocol and pathmtu and other functions in addition to the referred function of ICMP. First of all, we introduce icmpv6 error message.
Icmpv6 has four error message types. The first is unreachable destination; the second is the long package; the third is timeout; the four is that the parameters have problems. Each category has the corresponding error code. Here we sorted out a table for your reference.
| Type | Code | ||
| 1 | Destination Unreachable | 0 | Route not reaching goal |
| 1 | Banned connection with goal | ||
| 2 | Undefinition | ||
| 3 | Address unreachable | ||
| 4 | Port unreachable | ||
| 2 | packageToo Big | 0 | |
| 3 | Time Exceeded | 0 | The hop limit was exceeded in transmission |
| 1 | Fragment reassembly timeout | ||
| 4 | Parameter Problem | 0 | Header field error |
| 1 | The next Header type is not recognized | ||
| 2 | Unrecognized ipv6 option |
In addition, if the type of information packageis 128-255, the ICMPv6 packageis an information package, where 128 is a reply packageand 129 is a reply package. Rfc2461 and RFC2710 also respectively define neighbor discovery and multicast listening discovery. We sorted out the table for you, and suggested that you would reserve.
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| type130 | Multicast listener queries |
| type131 | Multicast listener report |
| type132 | Multicast listener quit |
| Type133 | Router request |
| Type134 | Router bulletin |
| Type135 | Neighbor request |
| Type136 | Neighbor bulletin |
| Type137 | Redirect |
It contains the neighbor discovery protocol and multicast listen discovery protocols. Neighbor discovery can be used to detect whether there is a conflict, on account that our address as ipv6 has no radio, so the function of arp is implemented by the NDP. What`s more, functions such as tracking the status of neighbors, routing, redirect, stateless address autoconfiguration and prefix to addressing can also be made through it.
Icmpv6 also introduced the concept of pathmtu. Ipv4 can be sharded on any device, while ipv6 requires only source sharding. Therefore, if the mtu of intermediate devices is small, transmission cannot be troublesome. When Icmpv6 error packages send “package too big”, they will return to the corresponding mtu common source device for reference. Finally, the smallest mtu must be obtained. Thus, this is the concept of pathmtu.
Icmpv6 is extremely critical, because without Icmpv6, ipv6 cannot be implemented. So save it quickly.
The icmp in ipv6
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