[c-nsp] LAM / Mobile IP in modern times

Alexander Clouter alex at digriz.org.uk
Tue Aug 10 06:10:27 EDT 2010


* Lincoln Dale <ltd at cisco.com> [2010-08-10 19:56:21+1000]:
> On 10/08/2010, at 6:35 PM, Alexander Clouter wrote:
> > I was toying with the idea internally of putting a tiny OSPF router into 
> > our VM cluster to drag IP's from one side of our organisation to the 
> > other.  
> reality is that many hosts and applications require and expect layer 2 
> connectivity for things other than IP unicast when they think they are 
> in the same IP subnet another host.
Thought it was obvious I was talking L3 here, maybe not.  If you are 
coupling hosts at L2 then you would be nuts to not move them as a group 
surely?  I probably was not clear when talking about the 'dead zone' 
VLAN at either site, there just would be no router on that VLAN.  An 
amendment is that you have a dedicated locally scoped same-VLAN-ID VLAN 
for just those nodes that need L2 lovin' to work on, have another pair 
of VLAN's for the L3.
> > The only remaining question is why for it's money have VMWare not done 
> > the trivial task of making OSPF part of their VMotion malarkey...*sigh*
> because its not /quite/ as simple as you suggest.
The awkward part I see is host based (not service) L3 connectivity.  The 
operating system would need work happily in a multihomed configuration 
and to understand what a dead gateway means.  This probably would not be 
easy to pull off on a Windows based guest, but it should be quite doable 
on....well *any* other OS :)

As a mentioned before though, unfortunately I never got this beyond the 
planning stage due to the 'quality' of the VMware consultants we hired :-/


Alexander Clouter
.sigmonster says: Minnie Mouse is a slow maze learner.

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