Re: [quicwg/base-drafts] Disabling Spin bit for what percentage of connections? (#3270)

Martin Thomson <notifications@github.com> Mon, 25 November 2019 06:40 UTC

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Subject: Re: [quicwg/base-drafts] Disabling Spin bit for what percentage of connections? (#3270)
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martinthomson requested changes on this pull request.



> @@ -4331,11 +4331,10 @@ Each endpoint unilaterally decides if the spin bit is enabled or disabled for a
 connection. Implementations MUST allow administrators of clients and servers
 to disable the spin bit either globally or on a per-connection basis. Even when
 the spin bit is not disabled by the administrator, implementations MUST disable
-the spin bit for a given connection with a certain likelihood. The random
-selection process SHOULD be designed such that on average the spin bit is
-disabled for at least one eighth of network paths. The selection process
-performed at the beginning of the connection SHOULD be applied for all paths
-used by the connection.
+the spin bit for at least a sixteenth of connections with an expectation that
+the spin bit is disabled for at least one eighth of network paths. The selection
+process performed at the beginning of the connection SHOULD be applied for all
+paths used by the connection.

In reviewing this last sentence, I am reminded that this provides a nice signal that might improve linkability.  I think that the requirement to perform the determination separately for every network path/connection ID as suggested above is better.

> @@ -4331,11 +4331,10 @@ Each endpoint unilaterally decides if the spin bit is enabled or disabled for a
 connection. Implementations MUST allow administrators of clients and servers
 to disable the spin bit either globally or on a per-connection basis. Even when
 the spin bit is not disabled by the administrator, implementations MUST disable
-the spin bit for a given connection with a certain likelihood. The random
-selection process SHOULD be designed such that on average the spin bit is
-disabled for at least one eighth of network paths. The selection process
-performed at the beginning of the connection SHOULD be applied for all paths
-used by the connection.
+the spin bit for at least a sixteenth of connections with an expectation that
+the spin bit is disabled for at least one eighth of network paths. The selection

> endpoints MUST disable their use of the spin bit on at least one in every 16 network paths, or for one in every 16 connection IDs. This ensures that the spin bit signal is disabled on approximately one in eight network paths.

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