[Bug 1907306] Re: networkd dhcpv4 client never attempts more than 2 renew and 2 rebind

[Dan Streetman]

** Description changed:

  [impact]
  
  networkd dhcpv4 client never attempts more than 2 renew and 2 rebind
  
  [test case]
  
  configure an interface to use dhcpv4; acquire a dhcpv4 address, then
  stop the dhcpv4 server, and wait for the networkd client to perform its
  renewals and rebinds before expiring the lease
  
+ using a 20 minute lease time as an example (all times are approximate
+ due to RFC-mandated random 'fuzz' time of -1 to +1 sec):
+ 
+ the current behavior would be to sent renew requests at:
+ 
+ 10:00
+ 13:45
+ 
+ and then rebind requests at:
+ 
+ 17:30
+ 18:45
+ 
+ then the lease would expire at 20:00
+ 
+ the correct/new behavior should be renew requests at:
+ 
+ 10:00
+ 13:45
+ 15:37
+ 16:37
+ 
+ and then rebind requests at:
+ 
+ 17:30
+ 18:45
+ 19:45
+ 
+ and then lease expiration at 20:00.
+ 
+ longer lease times would increase the number of retransmissions.
+ 
  [regression potential]
  
  any regression would likely result in problems receiving and/or
  maintaining a dhcpv4 address
  
  [scope]
  
- this is in progress upstream, and would need to be applied to all
- releases
+ this is needed in b/f/g/h.
+ 
+ this was fixed upstream in:
+ https://github.com/systemd/systemd/pull/17908
+ 
+ that was just added, so this is not fixed in any ubuntu release yet.
+ 
+ technically, this is needed in x as well, however I don't plan to
+ backport to x since 1) it reaches ESM soon and 2) the default network
+ management tool in x is ifupdown, not systemd-networkd.

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https://bugs.launchpad.net/bugs/1907306

Title:
  networkd dhcpv4 client never attempts more than 2 renew and 2 rebind

Status in systemd:
  New
Status in systemd package in Ubuntu:
  In Progress
Status in systemd source package in Bionic:
  In Progress
Status in systemd source package in Focal:
  In Progress
Status in systemd source package in Groovy:
  In Progress
Status in systemd source package in Hirsute:
  In Progress

Bug description:
  [impact]

  networkd dhcpv4 client never attempts more than 2 renew and 2 rebind

  [test case]

  configure an interface to use dhcpv4; acquire a dhcpv4 address, then
  stop the dhcpv4 server, and wait for the networkd client to perform
  its renewals and rebinds before expiring the lease

  using a 20 minute lease time as an example (all times are approximate
  due to RFC-mandated random 'fuzz' time of -1 to +1 sec):

  the current behavior would be to sent renew requests at:

  10:00
  13:45

  and then rebind requests at:

  17:30
  18:45

  then the lease would expire at 20:00

  the correct/new behavior should be renew requests at:

  10:00
  13:45
  15:37
  16:37

  and then rebind requests at:

  17:30
  18:45
  19:45

  and then lease expiration at 20:00.

  longer lease times would increase the number of retransmissions.

  [regression potential]

  any regression would likely result in problems receiving and/or
  maintaining a dhcpv4 address

  [scope]

  this is needed in b/f/g/h.

  this was fixed upstream in:
  https://github.com/systemd/systemd/pull/17908

  that was just added, so this is not fixed in any ubuntu release yet.

  technically, this is needed in x as well, however I don't plan to
  backport to x since 1) it reaches ESM soon and 2) the default network
  management tool in x is ifupdown, not systemd-networkd.

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