em0 link transitions when aliasing an interface

[Mike Tancsa]

Does anyone know of a way to avoid bouncing the em NIC when adding or 
removing aliases ?  In cases where the switch's port blocking kicks in, 
this can take the box off line for a problematic amount of time.

e.g.
ifconfig em0 19.168.13.9 netmask 255.255.255.252 alias

will down and up the interface.  I dont know of any other drivers that work 
this way.

On RELENG_4, it used to only have this problem behavior when the NIC was in 
autoneg.  But this is no longer the case in RELENG_5 as all media-opts 
(full / half / autoneg) work this way now.

Are there any tunables that would govern this behavior ?

Thanks for any insight,

         ---Mike


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Mike Tancsa,                                      tel +1 519 651 3400
Sentex Communications,                            mike at sentex.net
Providing Internet since 1994                    www.sentex.net
Cambridge, Ontario Canada                         www.sentex.net/mike