Re: NLB for Intranet Accross 2 Sites

"Hilding" <> wrote in message
news:09d8b9fe-4809-46b8-9704-...
I am designing a solution which has an intranet web server (2008) in
two locations, I can implement two (or more) NICs on the web servers
if necessary. Can anyone suggest the best approach for me to
configure this in NLB... I’m a bit confused by the unicast / multicast
options and have been advised that NLB can cause haywire with network
traffic broadcasts so I’m nervous about this.

RK - general rule of thumb is to use Unicast when Internet facing as not all
hardware supports multicasting of non-multicast range IP addresses.

I’m really looking for general guidance on one / two NICs, unicast /
multi-cast, same VLAN / doesn’t matter, same subnet / doesn’t matter,
etc. I don’t expect anyone to tell me how to set things up, just some
starter advice would be really appreciated.

RK - VLAN is really your ownly solution as all nodes in NLB are required to
be in the same subnet.

Another bent misconception to them being in the same vlan is that the nlb
hosts should be the only hosts in the vlan as this then becomes an effective
broadcast domain at packet level. However, Multicast mode does not replace
the physical mac address of the node dedicated NIC's, it adds a mutlicast mac
in the body of each packet, since most router (Switches and inter-vlan
routers) defautly drop this, the NLB IP addess seems to only work from within
the same VLAN. On CISCO Catalysts 6500's the following command needs to be
set:

mac-addr table static ????.????.???? vlan? interface fa?/?? fa?/??
disable-snooping

????.????.???? is the NLB assigned MAC (The cluster address). Interface of
both physically coonected nodes on the swith. Multicast is preferred as this
limits flooding of all ports in a VLAN, UNICAST is bas for flood creations.
You only need 1 NIC to be enabled per node in mutlicast


--
Garry Starck
MCITP, MCTS AS, MCSE 2003 Messaging, MCDBA


"Russ Kaufmann" wrote:

> "Hilding" <> wrote in message
> news:09d8b9fe-4809-46b8-9704-...
> I am designing a solution which has an intranet web server (2008) in
> two locations, I can implement two (or more) NICs on the web servers
> if necessary. Can anyone suggest the best approach for me to
> configure this in NLB... I’m a bit confused by the unicast / multicast
> options and have been advised that NLB can cause haywire with network
> traffic broadcasts so I’m nervous about this.
>
> RK - general rule of thumb is to use Unicast when Internet facing as not all
> hardware supports multicasting of non-multicast range IP addresses.
>
> I’m really looking for general guidance on one / two NICs, unicast /
> multi-cast, same VLAN / doesn’t matter, same subnet / doesn’t matter,
> etc. I don’t expect anyone to tell me how to set things up, just some
> starter advice would be really appreciated.
>
> RK - VLAN is really your ownly solution as all nodes in NLB are required to
> be in the same subnet.
>
>

"Garry Starck" <vjsparx@REMOVE_CAPS_INVALIDhotmail.com> wrote in message
news:7B9880A3-161C-4550-931F-...
> Another bent misconception to them being in the same vlan is that the nlb
> hosts should be the only hosts in the vlan as this then becomes an
> effective
> broadcast domain at packet level. However, Multicast mode does not replace
> the physical mac address of the node dedicated NIC's, it adds a mutlicast
> mac
> in the body of each packet, since most router (Switches and inter-vlan
> routers) defautly drop this, the NLB IP addess seems to only work from
> within
> the same VLAN. On CISCO Catalysts 6500's the following command needs to be
> set:
>
> mac-addr table static ????.????.???? vlan? interface fa?/?? fa?/??
> disable-snooping
>
> ????.????.???? is the NLB assigned MAC (The cluster address). Interface of
> both physically coonected nodes on the swith. Multicast is preferred as
> this
> limits flooding of all ports in a VLAN, UNICAST is bas for flood
> creations.
> You only need 1 NIC to be enabled per node in mutlicast

Not all equipment, especially that on the Internet, will support
multicasting of non-multicast range addresses. Thus, it works fine in an
internal environment, but not when Internet facing for most of those on the
Internet.

As to the communication issues, the nodes must be on the same subnet, thus
the need for a VLAN or equiv for it to work across multiple locations.

--
Russ Kaufmann,
MVP, MCSE: Messaging and Security, MCT, MCITP, MCTS and other stuff

ClusterHelp.com, a Microsoft Certified Gold Partner
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