| IP option 12, MTU Reply |
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Description | Glossary | RFCs | Publications | Obsolete RFCs |
| Protocol suite: | TCP/IP. |
| Protocol type: | Connectionless network layer protocol. |
| Option length: | 4 bytes. |
| Host implementation: | Obsolete. |
| Router implementation: | Obsolete. |
| Links: | IANA: IP option numbers. |
The IP MTU Reply option was used to return the minimum MTU detected to the sender of an MTU Probe option. This option is obsolete.
| MAC header | IP header | IP option 12 | Data |
IP Option 12:
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Type | Length | MTU Value | |||||||||||||||||||||||||||||
Type. 8 bits. Set to 12.
| 00 | 01 | 02 | 03 | 04 | 05 | 06 | 07 |
|---|---|---|---|---|---|---|---|
| C | Class | Option | |||||
C, Copy flag. 1 bit. Cleared to 0.
This option is not to be copied into all fragments.Class. 2 bits. Cleared to 0.
This is a control option.Option. 5 bits. Set to 12.
The IP option number.
Length.
8 bits. Set to 4.
Total length of the option.
MTU Value.
16 bits.
Contains the lowest MTU value detected by a previous
MTU Probe option.
RFCs:
[RFC 1063] IP MTU Discovery Options.
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Description | Glossary | RFCs | Publications | Obsolete RFCs |