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-Hold generated local macs at 42: prefix to avoid conflict with FE: and make libvirt do unique tap addresses

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git-svn-id: https://svn.code.sf.net/p/xcat/code/xcat-core/trunk@7673 8638fb3e-16cb-4fca-ae20-7b5d299a9bcd
This commit is contained in:
jbjohnso 2010-09-27 18:49:50 +00:00
parent 0fe24d95bd
commit 8ba1a33254
1 changed files with 10 additions and 5 deletions
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15
perl-xCAT/xCAT/VMCommon.pm
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@ -225,11 +225,16 @@ sub genMac { #Generates a mac address for a node, does NOT assure uniqueness, ca
$tail =~ s/(..)(..)(..)/:$1:$2:$3/;
return $prefix.$tail;
}
my $allbutmult = 0xfeff; # to & with a number to ensure multicast bit is *not* set
my $locallyadministered = 0x200; # to | with the 16 MSBs to indicate a local mac
my $leading = int(rand(0xffff));
$leading = $leading & $allbutmult;
$leading = $leading | $locallyadministered;
#my $allbutmult = 0xfeff; # to & with a number to ensure multicast bit is *not* set
#my $locallyadministered = 0x200; # to | with the 16 MSBs to indicate a local mac
#my $leading = int(rand(0xffff));
#$leading = $leading & $allbutmult;
#$leading = $leading | $locallyadministered;
#for the header, we used to use all 14 possible bits, however, if a guest mac starts with 0xfe then libvirt will construct a bridge that looks identical
#First thought was to go to 13 bits, but by fixing our generated mac addresses to always start with the same byte and still be unique
#this induces libvirt to do unique TAP mac addresses
my $leading = int(rand(0xff));
$leading = $leading & 0x4200;
#If this nodename is a resolvable name, we'll use that for the other 32 bits
my $low32;
my $n;