58 lines
1.3 KiB
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58 lines
1.3 KiB
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=================
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Increase IPv6 MTU
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=================
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.. meta::
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:author: zzz
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:created: 2016-08-23
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:thread: http://zzz.i2p/topics/2181
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:lastupdated: 2016-12-02
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:status: Closed
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:target: 0.9.28
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:implementedin: 0.9.28
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.. contents::
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Overview
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========
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This proposal is to increase the max SSU IPv6 MTU from 1472 to 1488.
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Implemented in 0.9.28.
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Motivation
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==========
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IPv4 MTU must be a multiple of 16, + 12. IPv6 MTU must be a multiple of 16.
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When IPv6 support was first added years ago, we set the max IPv6 MTU to 1472, less than the
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IPv4 MTU of 1484. This was to keep things simple and ensure the IPv6 MTU was less
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than the existing IPv4 MTU. Now that IPv6 support is stable, we should be able to
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set the IPv6 MTU higher than the IPv4 MTU.
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The typical interface MTU is 1500, so we can reasonably increase the IPv6 MTU by 16 to 1488.
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Design
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======
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Change the max from 1472 to 1488.
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Specification
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=============
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In the "Router Address" and "MTU" sections of the SSU overview,
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change the max IPv6 MTU from 1472 to 1488.
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Migration
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=========
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We expect that routers will set the connection MTU as the minimum of the local and remote
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MTU, as usual. No version check should be required.
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If we determine that a version check is required, we will set a minimum version
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level of 0.9.28 for this change.
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