AD Sites and Services Transports:  IP, RPC and SMTP.  What's the difference?

Posted on 2006-04-21
Last Modified: 2008-03-06
I am running AD on several Windows 2000 and 2003 servers.  The domain is in native mode and the GCs / PDC emulators are all Windows 2003 server.
I have 4 sites in a hub/spoke topology connected via T1s and VPN:
New York (NY)  -  HUB - 2 Domain Controllers:  NYDC1 and NYDC2
Wash D.C. (DC) - 2 Domain Controllers:  DCDC1 and DCDC2
Las Angeles (LA) - 1 Domain Controller:  LADC1
Sydney, AU  (SY) - 1 Domain Controller:  SYDC1

We have one domain and 4 different subnets for each corresponding location.  In AD Sites and Services, I have IP and SMTP listed as Inte-Site Transports and I have turned off the "Bridge all site links" to clean up the replication partners.  All domain controllers replicate with NYDC1 and NYDC2 as they are in the Hub site.

Now, when I go into the NTDS Settings for NYDC1, I see all other Domain Controllers appear as replication partners which is normal.  If I click on the replication connection for NYDC2 and go to properties, I see that it is configured to use RPC for the replication transport which is again normal since both DCs are in the same site.

My question is about the replication transport options.  If I click it the Transport pulldown on the properties for a connection I have three options:  IP, RPC and SMTP

I do not recall being taught about 3 transport options... I recall SMTP being used for remote sites (with latency), and RPC being for DCs within one site (fast connection) but I do not remember the IP option.  What should I be using for the remote sites to replicate with the Hub?  I have them set for IP now, but I suspect that IP and RPC are synonymous (but why have them both listed!)

Any ideas?
Question by:BBG-BBGM
    1 Comment
    LVL 12

    Accepted Solution

    There is a very extensive explanation of Active Directory replication in the Technet Library:

    In that document, no other replication transports other than synchonous RPC-over-IP and asynchronous SMTP-over-IP are mentioned.

    Automatically created replication connectors default to RPC for intrasite servers, and IP for intersite servers, but both transports use synchronous RPC-over-IP.

    Featured Post

    IT, Stop Being Called Into Every Meeting

    Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

    Join & Write a Comment

    I guess it is not common knowledge to most Wintel engineers/administrators: If you have an SNMP-based monitoring system in your environment (and it's common to have SNMP or Syslog) it's reasonably easy to enable monitoring of the Windows Event logs,…
    Scenerio: You have a server running Server 2003 and have applied a retail pack of Terminal Server Licenses.  You want to change servers or your server has crashed and you need to reapply the Terminal Server Licenses. When you enter the 16-digit lic…
    Migrating to Microsoft Office 365 is becoming increasingly popular for organizations both large and small. If you have made the leap to Microsoft’s cloud platform, you know that you will need to create a corporate email signature for your Office 365…
    Excel styles will make formatting consistent and let you apply and change formatting faster. In this tutorial, you'll learn how to use Excel's built-in styles, how to modify styles, and how to create your own. You'll also learn how to use your custo…

    754 members asked questions and received personalized solutions in the past 7 days.

    Join the community of 500,000 technology professionals and ask your questions.

    Join & Ask a Question

    Need Help in Real-Time?

    Connect with top rated Experts

    19 Experts available now in Live!

    Get 1:1 Help Now