NLB over wan with Windows 2008 Server for CAS role

Lehr · Joined: 09 Jan 2008 Posts: 22

Is it possible to set up NLB cluster via WAN link with windows 2008 server ?
That's important to me because we are going to implement Exchange CCR
cluster (for Mailbox) over WAN with win2k8, and we also need to provide high
availability for Exchange Client Access, with one in Location A, and second
in Location B, linked via WAN.
So I wonder is it possible to do that with NLB cluster

Maybe it is enogh to make two same CNAME records with different IP's(1 in
subnet Location A, and second in subnet Location B) ?

Thank you!

Archived from group: microsoft>public>exchange>clustering

Mark Arnold [MVP] · Joined: 05 Aug 2007 Posts: 1126

On Wed, 13 Feb 2008 13:37:01 -0800, Lehr
wrote:

>Is it possible to set up NLB cluster via WAN link with windows 2008 server ?
>That's important to me because we are going to implement Exchange CCR
>cluster (for Mailbox) over WAN with win2k8, and we also need to provide high
>availability for Exchange Client Access, with one in Location A, and second
>in Location B, linked via WAN.
>So I wonder is it possible to do that with NLB cluster
>
>Maybe it is enogh to make two same CNAME records with different IP's(1 in
>subnet Location A, and second in subnet Location B) ?
>
>Thank you!

No, not really. You need to address your resilience design because
that doesn't sound too clever right now.

Russ Kaufmann [MVP] · Joined: 05 Aug 2007 Posts: 69

"Lehr" wrote in message @microsoft.com...
> And what about putting two same CNAME records in with different IP ?
> One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
> Would that provide HA in case one of the CAS servers goes down?

Nope. That would be the same thing as doing DNS round robin. It is not an HA
solution. If one server were to fail, half of the traffic would still be
directed to it.

--
Russ Kaufmann
MVP - Windows Server - Clustering
ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

The next ClusterHelp classes are:
Mar 10- 13 in Denver
May 12-15 in New York

Russ Kaufmann [MVP] · Joined: 05 Aug 2007 Posts: 69

"Lehr" wrote in message @microsoft.com...
> Is it possible to set up NLB cluster via WAN link with windows 2008 server
> ?

Each node in an NLB cluster has to be in the same network segment. So, if
you configure a VLAN spanning sites, then you could do that.

> That's important to me because we are going to implement Exchange CCR
> cluster (for Mailbox) over WAN with win2k8,

You realize, of course, that each node in a CCR cluster has to be in the
same AD site, right?

> and we also need to provide high
> availability for Exchange Client Access, with one in Location A, and
> second
> in Location B, linked via WAN.
> So I wonder is it possible to do that with NLB cluster

Yes, it is, but it will require using a VLAN.

> Maybe it is enogh to make two same CNAME records with different IP's(1 in
> subnet Location A, and second in subnet Location B) ?

Nope, that won't work. Sorry.

--
Russ Kaufmann
MVP - Windows Server - Clustering
ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

The next ClusterHelp classes are:
Mar 10- 13 in Denver
May 12-15 in New York

Lehr · Joined: 09 Jan 2008 Posts: 22

"Russ Kaufmann [MVP]" wrote:

> "Lehr" wrote in message
> @microsoft.com...
> > And what about putting two same CNAME records in with different IP ?
> > One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
> > Would that provide HA in case one of the CAS servers goes down?
>
> Nope. That would be the same thing as doing DNS round robin. It is not an HA
> solution. If one server were to fail, half of the traffic would still be
> directed to it.
>

And if we turn off round robin in DNS? hm

Andy David {MVP} · Joined: 05 Aug 2007 Posts: 591

On Wed, 13 Feb 2008 15:24:01 -0800, Lehr
wrote:

>
>
>"Russ Kaufmann [MVP]" wrote:
>
>> "Lehr" wrote in message
>> @microsoft.com...
>> > And what about putting two same CNAME records in with different IP ?
>> > One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
>> > Would that provide HA in case one of the CAS servers goes down?
>>
>> Nope. That would be the same thing as doing DNS round robin. It is not an HA
>> solution. If one server were to fail, half of the traffic would still be
>> directed to it.
>>
>
>And if we turn off round robin in DNS? hm

Then it still wont work. Unless you remove the downed servers ip from
the CNAME and then wait for client TTL to expire.

Why not just build the NLB correctly using the NLB features of Windows
or a 3rd party solution?

Lehr · Joined: 09 Jan 2008 Posts: 22

"Andy David {MVP}" wrote:

> On Wed, 13 Feb 2008 15:24:01 -0800, Lehr
> wrote:
>
> >
> >
> >"Russ Kaufmann [MVP]" wrote:
> >
> >> "Lehr" wrote in message
> >> @microsoft.com...
> >> > And what about putting two same CNAME records in with different IP ?
> >> > One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
> >> > Would that provide HA in case one of the CAS servers goes down?
> >>
> >> Nope. That would be the same thing as doing DNS round robin. It is not an HA
> >> solution. If one server were to fail, half of the traffic would still be
> >> directed to it.
> >>
> >
> >And if we turn off round robin in DNS? hm
>
> Then it still wont work. Unless you remove the downed servers ip from
> the CNAME and then wait for client TTL to expire.
>
> Why not just build the NLB correctly using the NLB features of Windows
> or a 3rd party solution?

My question was is it possible to build NLB with two nodes in different
subnets, and I got the answer that it is not.
But...maybe I'm wrong...but I still think it's going to work...
In that case NLB is going to have two IP adressess, one from NODE A subnet,
and one from NODE B subnet, right? And when the client requests IP for, NLB,
he will get
IP from his local subnet, and that will work if round robin is turned off in
DNS.
And if one of nodes goes down, NLB would know that and everything goes to
other node.

Am I wrong?

Russ Kaufmann [MVP] · Joined: 05 Aug 2007 Posts: 69

"Lehr" wrote in message @microsoft.com...
>> > And what about putting two same CNAME records in with different IP ?
>> > One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
>> > Would that provide HA in case one of the CAS servers goes down?
>>
>> Nope. That would be the same thing as doing DNS round robin. It is not an
>> HA
>> solution. If one server were to fail, half of the traffic would still be
>> directed to it.
>>
>
> And if we turn off round robin in DNS? hm

There is no such thing as turning off round robin. It is a state of being by
having multiple records that end up pointing to different IPs. Whether you
use the same host name multiple times or whether you use cnames doesn't
matter, the end result is the same.

--
Russ Kaufmann
MVP - Windows Server - Clustering
ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

The next ClusterHelp classes are:
Mar 10- 13 in Denver
May 12-15 in New York

Russ Kaufmann [MVP] · Joined: 05 Aug 2007 Posts: 69

"Lehr" wrote in message @microsoft.com...
>> >> > And what about putting two same CNAME records in with different IP ?
>> >> > One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
>> >> > Would that provide HA in case one of the CAS servers goes down?
>> >>
>> >> Nope. That would be the same thing as doing DNS round robin. It is not
>> >> an HA
>> >> solution. If one server were to fail, half of the traffic would still
>> >> be
>> >> directed to it.
>> >>
>> >
>> >And if we turn off round robin in DNS? hm
>>
>> Then it still wont work. Unless you remove the downed servers ip from
>> the CNAME and then wait for client TTL to expire.
>>
>> Why not just build the NLB correctly using the NLB features of Windows
>> or a 3rd party solution?
>
> My question was is it possible to build NLB with two nodes in different
> subnets, and I got the answer that it is not.
> But...maybe I'm wrong...but I still think it's going to work...

OK, then why bother asking... Test it for yourself, if that is what it
takes to convince you.

> In that case NLB is going to have two IP adressess, one from NODE A
> subnet,
> and one from NODE B subnet, right? And when the client requests IP for,
> NLB,
> he will get
> IP from his local subnet, and that will work if round robin is turned off
> in
> DNS.
> And if one of nodes goes down, NLB would know that and everything goes to
> other node.
>
> Am I wrong?

Yes, it won't work, but feel free to try it.

--
Russ Kaufmann
MVP - Windows Server - Clustering
ClusterHelp.com, a Microsoft Certified Gold Partner
Web http://www.clusterhelp.com
Blog http://msmvps.com/clusterhelp

The next ClusterHelp classes are:
Mar 10- 13 in Denver
May 12-15 in New York

Lehr · Joined: 09 Jan 2008 Posts: 22

OK, you convinced me Smile

"Russ Kaufmann [MVP]" wrote:

> "Lehr" wrote in message
> @microsoft.com...
> >> >> > And what about putting two same CNAME records in with different IP ?
> >> >> > One IP for CAS1 in Location A, and second IP for CAS2 in Location B.
> >> >> > Would that provide HA in case one of the CAS servers goes down?
> >> >>
> >> >> Nope. That would be the same thing as doing DNS round robin. It is not
> >> >> an HA
> >> >> solution. If one server were to fail, half of the traffic would still
> >> >> be
> >> >> directed to it.
> >> >>
> >> >
> >> >And if we turn off round robin in DNS? hm
> >>
> >> Then it still wont work. Unless you remove the downed servers ip from
> >> the CNAME and then wait for client TTL to expire.
> >>
> >> Why not just build the NLB correctly using the NLB features of Windows
> >> or a 3rd party solution?
> >
> > My question was is it possible to build NLB with two nodes in different
> > subnets, and I got the answer that it is not.
> > But...maybe I'm wrong...but I still think it's going to work...
>
> OK, then why bother asking... Test it for yourself, if that is what it
> takes to convince you.
>
> > In that case NLB is going to have two IP adressess, one from NODE A
> > subnet,
> > and one from NODE B subnet, right? And when the client requests IP for,
> > NLB,
> > he will get
> > IP from his local subnet, and that will work if round robin is turned off
> > in
> > DNS.
> > And if one of nodes goes down, NLB would know that and everything goes to
> > other node.
> >
> > Am I wrong?
>
> Yes, it won't work, but feel free to try it.
>
>
> --
> Russ Kaufmann
> MVP - Windows Server - Clustering
> ClusterHelp.com, a Microsoft Certified Gold Partner
> Web http://www.clusterhelp.com
> Blog http://msmvps.com/clusterhelp
>
> The next ClusterHelp classes are:
> Mar 10- 13 in Denver
> May 12-15 in New York
>

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