Add a nodeAttr to enable/disable peer path MTU discovery. Updates #311 Signed-off-by: Val <valerie@tailscale.com>
Replace CanPMTUD() with ShouldPMTUD() to check if peer path MTU discovery should be enabled, in preparation for adding support for enabling/disabling peer MTU dynamically. Updated #311 Signed-off-by: Val <valerie@tailscale.com>
