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Your question title says ET which is the Edge Transport role, this would be placed in the DMZ and sanatize your mail before it gets to youe Exchange organisation.<br />
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The Hub Transport Role is an internal role and is required. &nbsp;Even if you don't have the ET role (which is not required)
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Your question title says ET which is the Edge Transport role, this would be placed in the DMZ and sanatize your mail before it gets to youe Exchange organisation.

The Hub Transport Role is an internal role and is required.  Even if you don't have the ET role (which is not required)

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Great thank you. So as for the HT placement, would it be best to locate that on the mail servers or the CAS in a NLB cluster?
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Great thank you. So as for the HT placement, would it be best to locate that on the mail servers or the CAS in a NLB cluster?

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I am currently planning a Exchange 2007 to 2010 migration for a client that needs to have full redundancy in the design. Currently they run a single Exchange 2007 server with all the roles, and 2 spam filters. My question is do i realy need the Edge Transport role in the new 2010 environment? And were to place the HT role?<br />
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I am currently planning 2 Mailbox servers running DAG and HT, 2 CAS servers in a NLB cluster, using the 2 inbound spamfliters to act as the ET's.<br />

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I am currently planning a Exchange 2007 to 2010 migration for a client that needs to have full redundancy in the design. Currently they run a single Exchange 2007 server with all the roles, and 2 spam filters. My question is do i realy need the Edge Transport role in the new 2010 environment? And were to place the HT role?

I am currently planning 2 Mailbox servers running DAG and HT, 2 CAS servers in a NLB cluster, using the 2 inbound spamfliters to act as the ET's.


Exchange 2010 ET role is is necessary

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Within Internet message handling services (MHS), a message transfer agent or mail transfer agent (MTA) or mail relay is software that transfers electronic mail messages from one computer to another using a client–server application architecture. A MTA implements both the client (sending) and server (receiving) portions of the Simple Mail Transfer Protocol (SMTP). The terms mail server, mail exchanger, and MX host may also refer to a computer performing the MTA function. The Domain Name System (DNS) associates a mail server to a domain with mail exchanger (MX) resource records containing the domain name of a host providing MTA services.

Email Servers

Network design and methodology, also known as network architecture, is the design of a communication network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation. In telecommunication, the specification of a network architecture may also include a detailed description of products and services delivered via a communications network, as well as detailed rate and billing structures under which services are compensated.