On 2014/09/26 07:42, Alexander Hall wrote:
> Before performing a dhcp request, /etc/netstart explicitly takes the
> interface down. As noted (by me) at g2k14, and also at work, this results
> in a significant delay in getting the address.
>
> I'm not all into enterprise switch magic, but someone hinted that this
> could come from the switch reinitializing the port, with all kinds of
> spanning-tree magic etc involved.
No magic - it just doesn't forward for a certain number of seconds
while it listens for incoming spanning-tree BPDUs. Switch config is
dubious though, normally you would use "switchport mode access" and
"spanning-tree portfast" or equivalent on access ports. (HP Procurve
switches have a different, less intrusive, default where they do
listen for BPDUs but only for 3 seconds, so you don't usually need
to fiddle with them).
> Looking at the history of pre-dhclient ' down' in /etc/netstart
> (introduced in -r1.43, 18 Sep 1998 18:42:10), I cannot see a reason
> for keeping it.
>
> This cuts 'sh /etc/netstart' time from ~minute to ~nothing at work.
>
> OK?
Commit log was "apply media directives on dhcp interfaces" - I'm
wondering if there may be NICs that only reset media if they
are brought down+up. However if that is the case, the user could
add 'down' to the hostname.if line themselves..
I think this would only be a problem where you re-run netstart
when the system is already up; does that match your experience?
> /Alexander
>
>
> Index: netstart
> ===================================================================
> RCS file: /cvs/src/etc/netstart,v
> retrieving revision 1.141
> diff -u -p -r1.141 netstart
> --- netstart 12 Jul 2014 14:39:31 -0000 1.141
> +++ netstart 26 Sep 2014 05:32:22 -0000
> @@ -63,7 +63,7 @@ ifstart() {
> [ "$name" = "NONE" ] && name=
> [ "$mask" = "NONE" ] && mask=
> [ "$bcaddr" = "NONE" ] && bcaddr=
> - cmd="ifconfig $if $name $mask $bcaddr $ext1 $ext2 down"
> + cmd="ifconfig $if $name $mask $bcaddr $ext1 $ext2"
> cmd="$cmd;dhclient $if"
> dhcpif="$dhcpif $if"
> ;;
>
>
