Top 10 Things to Know About OCS 2007 R2

re: Top 10 Things to Know About OCS 2007 R2

Petri — Thu, 22 Jan 2009 01:30:36 GMT

Many thanks to you Sean, but you must clarify one thing!!

> 7. No More DNAT

When we are using virtual IP addresses for front end servers we are saying it as a DNAT. So far it seems that you (OCS team) have different mean for DNAT. Could you draw few pictures and show us the differences about this. Please

re: Top 10 Things to Know About OCS 2007 R2

Alenat — Fri, 13 Mar 2009 16:16:12 GMT

The same question as for Petri. NAT is the way LB operates. If we connect from a Client to a VIP of LB the device translates destination IP to an IP of one of balanced FE. From my understanding it is DNAT since destination IP was changed. At the same time the LB should operate in SNAT replacing source IP of the Client to IP address of the LB so FE replies to LB, not to the Client directly. So it looks for me that LB must operate in both DNAT and SNAT modes. Where is my mistake? A network diagram would be great.

Thank you!

Alex

re: Top 10 Things to Know About OCS 2007 R2

Sean Olson — Sat, 14 Mar 2009 00:05:59 GMT

To answer your question Alex, a given virtual IP address on a load balancer will be configured either to work in DNAT mode -or- in SNAT mode. They are not used in combination. As you point out, any load balancer is going to act as a NAT. All we are saying is that we want the VIP used for OCS 2007 pools to be configured to use source NAT instead of destination NAT. Specifically, I'm talking about NAT as seen by the server and not by the client. Source NAT is preferrable for the server when it needs to connect to another server in the same pool (behind the same VIP)