Network Load Balancing with Win 2003 Server - 6500 Config

[ckerry]

We plan to implement Network Load Balancing with Win 2003 server. The cluster comprises 5 servers that are teamed to 2 x 6500 switches.

Servers are members of the same VLAN.

6500 are equipped with MSFC & PFC.

Will I need to make any configuration changes on the 6500 to support the above implemetation.

Regards - CK

[carenas123]

You need to configure IOS-Server Load Balancing(SLB) feature.Please refer the following links how to configure IOS-Server Load Balancing(SLB) feature.

http://www.cisco.com/en/US/products/hw/switches/ps708/products_white_paper09186a00800924fd.shtml

http://www.cisco.com/univercd/cc/td/doc/product/software/ios121/121newft/121limit/121e/121e3/iosslb3.htm

[ckerry]

Thanks for your i/p, however, the requirement is to implement NLB (network load balancing) on microsoft server 2003 not the Cisco offering (SLB).

[dave.keith]

If you intend on connecting the server ports directly to 6500 ports, be careful of the flooding that will occur. The Windows NLB 'feature' operates in it's default mode by 'hiding' the NICs MAC address, instead it responds to ARPs with a bogus MAC that never appears as a ethernet source address, which means the switch never learns the address and as a result it floods the packets to all interfaces. That's how the multiple servers get all of the traffic. This has caused grief, especially on lower speed lines :(

There is an alternative. Wire the servers to a hub, and in turn connect the hub to the 6500. There is a registry value to edit that will cause the servers to use their normal MAC addresses (in both sent packets and in ARP replies). So now the switch can learn the addresses, and so will not flood the traffic to the entire network.

See the Microsoft tech article KB193602 for details.

Good luck,

Dave

[andy.steere]

I'm very interested in this topic too... as we have several MS clusters doing NLB. Tips and suggestions are requested!

From what I can gather, there appears to be two ways to do MS NLB in Windows2003. One I call "multicast" and the other "broadcast". I don't know how to configure the multicast way, where the servers use IP-Multicast to talk among themselves. It may be a fairly simple matter to have the 6500 participate, but I'm not yet "multicast aware". I do know that doing nothing to the config does not make it work. ;-)

The "broadcast" method is what we're doing now. Basically what happens is the switch is unable to nail down where to send packets and ends up broadcasting the traffic out to everything in the VLAN. This seems to be working ok, but there are at least a couple caveats.

First is you want to limit what else is on that VLAN, to keep them from being exposed to all the extra traffic. Preferably only cluster members are in the VLAN.

It was also suggested to me, by a Cisco SE, to add these lines to the VLAN router interface:

no ip redirects

no ip unreachables

no ip route-cache cef

I am unable to confirm or deny if these help, or what effect they really have.

Hopefully somebody here has more experience with MS NLB and can give us some tips!

[ckerry]

Thanks for I/P

This project is on ice at present - will update forum when it kicks off again and post solution implemented.

CK