Rich Bashaw
Guest
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 Posted:
Thu Dec 22, 2005 1:58 am Post subject:
Exchange 2003 Front End NLB or round Robin DNS? |
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Hi,
I have 2 Exchange 2003 front end servers setup with NLB. It appears to be
working fine. I have noticed that I always get my mail from the same server.
I saw this posting in the newsgroups:
| Quote: | When you have NLB installed on a cluster, what happen is that the subnet
address space where your NLB server is sitting on, is classified in buckets; |
each bucket is a bunch of ips that a particular node is designated to serve;
so when you connect to the VIP of your NLB server the cluster will determine
based on your local ip, which node of the cluster will serve you; that is
why you are getting a response from node 2 all the time. <<
This doesn't seem to be truely 'load balancing". I mean, I guess it is
becasue its splitting up the IPs between the 2 servers.
I have a separate "spam filter" server in my DMZ that processes the incoming
mail and then forwards it off to the virtual IP of the NLB. My thinking was
that the NLB servers would spread the work between the 2 front end servers to
balance the load. But if the above posting is true, the IP of the spam filter
gets assigned to the same FE server and it processes all the inbound mail. I
guess outbound would be shared between the 2.
Is round robin DNS a better solution for what i am trying to do?
Thanks
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Russ Kaufmann [MVP]
Guest
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| Posted:
Fri Dec 23, 2005 1:58 am Post subject:
Re: Exchange 2003 Front End NLB or round Robin DNS? |
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| Quote: | When you have NLB installed on a cluster, what happen is that the subnet
address space where your NLB server is sitting on, is classified in
buckets;
each bucket is a bunch of ips that a particular node is designated to
serve;
|
Actually, it is the IP and the port together (so, the socket number), but it
ends up the same when dealing with the same port, so this description is
still valid.
| Quote: | so when you connect to the VIP of your NLB server the cluster will
determine
based on your local ip, which node of the cluster will serve you; that is
why you are getting a response from node 2 all the time.
|
In your case with your spam device, this is true.
| Quote: | This doesn't seem to be truely 'load balancing". I mean, I guess it is
becasue its splitting up the IPs between the 2 servers.
|
It is load balancing, but you only have one client in this case, the spam
device.
| Quote: | I have a separate "spam filter" server in my DMZ that processes the
incoming
mail and then forwards it off to the virtual IP of the NLB. My thinking
was
that the NLB servers would spread the work between the 2 front end servers
to
balance the load. But if the above posting is true, the IP of the spam
filter
gets assigned to the same FE server and it processes all the inbound mail.
I
guess outbound would be shared between the 2.
Is round robin DNS a better solution for what i am trying to do?
|
Is one FE overloaded? If not, then don't sweat it. Round robin is not the
answer because in round robin if one fails, it will still try to send to a
down server. At least with NLB, you will have some redundancy in the event
of a failure.
--
Russ Kaufmann
MVP - Windows Server - Clustering
http://www.clusterhelp.com - Cluster Website
http://msmvps.com/clusterhelp - Blog |
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