RE: nlb mode
From: Juan (Juan_at_discussions.microsoft.com)
Date: 11/09/04
- Next message: Mike Rosado [MSFT]: "Re: W2k3 Server - Cluster & Printing Drivers"
- Previous message: Juan: "RE: Multiple NLB Clusters on a Single Network Adapter"
- In reply to: Param R.: "nlb mode"
- Next in thread: Param R.: "Re: nlb mode"
- Reply: Param R.: "Re: nlb mode"
- Messages sorted by: [ date ] [ thread ]
Date: Tue, 9 Nov 2004 07:09:08 -0800
Hi,
In my experience I have used both unicast and multicast.
It all depends on what your NLB hosts will be doing and if they need to
perform inter-host communication between each other.
If your nodes do not need to see each other I would leave the default mode
unicast and deploy the NLB clusters but this mode those flood all of the
switch ports.
If the nodes in the NLB cluster need to see each then multicast would be a
good choice.
Both modes of operation have their pros and cons. The advantages of unicast
mode are that it works seamlessly with all routers and layer-2 switches (and
layer-3 switches which are configured to operate in layer-2 mode).
The disadvantages are:
• Unicast mode induces switch flooding, where all switch ports are flooded
with NLB traffic, even ports to which non-NLB servers are attached;
• Since all hosts in the cluster have the same IP Address and the same MAC
Address, there is no inter-host communication possible between the hosts
configured in unicast mode.
Multicast allows inter-host communication because it adds a layer two
multicast address to the cluster instead of changing it and this makes
inter-host communication possible as the hosts retain their original unique
MAC addresses and already have unique Dedicated IP Addresses. However, in
multicast mode, the ARP reply sent out by a host in the cluster, in response
to an ARP request, maps the clusters unicast IP Address to its multicast MAC
Address. Such a mapping in an ARP reply is rejected by some routers and so
administrator must add a static ARP entry in the router mapping the Cluster
IP Address to its MAC Address
Example in my experience why I chose multicast versus unicast was that all
web content on the NLB hosts had to be identical.
And updating the content was only performed on 1 of the nodes then the data
from that node was replicated out to all the other nodes. This requires
inter-host communication.
Regards,
Juan
"Param R." wrote:
> Hi all, we are in the process of setting up a new NLB environment running
> 2003 Web. What is the recommended NLB Mode for performance and
> manageability? Unicast or MultiCast? All servers have dual INTEL gigabit
> nics. The switches are Dell 5324 Gigabit switches etc.
>
> TIA!
>
>
>
- Next message: Mike Rosado [MSFT]: "Re: W2k3 Server - Cluster & Printing Drivers"
- Previous message: Juan: "RE: Multiple NLB Clusters on a Single Network Adapter"
- In reply to: Param R.: "nlb mode"
- Next in thread: Param R.: "Re: nlb mode"
- Reply: Param R.: "Re: nlb mode"
- Messages sorted by: [ date ] [ thread ]
Relevant Pages
|
