Topologies and Routing for Microsoft Exchange Server 2007Sandy MillarArchitect

UNC306

Agenda

Active Directory sites as routing boundariesService components of mail routingMessage route determinationRouting in a coexistence environmentMigration (transition) considerations

Active Directory Sites Are Routing and Service Discovery Boundary

Automatic discovery for all Exchange services within an Active Directory site

AD Topology ServiceMailbox SubmissionHub TransportClient Access

Routing decisionsbased upon ADsite topology

From:To:

1. User composes message in Outlook and it is stored in users Outbox

2. Mailbox submission service listens for store event notification of new message and notifies an in-site Hub Transport

RPC

3. Hub Transport retrieves message from source mailbox

4. Hub Transport categorizes message and delivers to a Hub Transport in target AD site5. Hub Transport applies message policies

6. Hub Transport submits message to mailbox server in target AD site

Mailbox

Mailbox

Hub Transport

Hub Transport

Message Delivery Flow

Direct Connect Primary

Routing Path DecisionsPrimary delivery path is direct

From: Joe@Site1To: Sally@site4

First backoff location path 1

Second backoff location path 1

IP S

ite Li

nk

Cost =

50

IP Site LinkCost = 50

IP Site Link

Cost = 50IP Site LinkCost = 250

Back off path calculated using least-cost route of AD IP Site Links starting from destination AD Site

Backoff Path 1 [4 -> 3 -> 2 -> 1 = 150]

Backoff Path 2 [4 -> 2 -> 1 = 300]

From: Joe@Site1To: Sally@site4

Delayed Fan-out (Bifurcation)

IP S

ite

Link

Cost =

50

IP Site Link

Cost = 50

IP Site

Link

Cost =

50

IP Site LinkCost = 50

IP S

ite

Link

Cost =

5

0

From: Joe@Site1To: Sally@Site4; Mike@Site5;Sue@Site6

From: Joe@Site1To: Mike@Site5; Sue@Site6

From: Joe@Site1To: Sue@Site6

From: Joe@Site1To: Sally@Site4

From: Joe@Site1To: Mike@Site5

AD Site Requirements

Dedicated AD sites for ExchangeBest practice in Exchange 2003 in many environmentsIn Exchange 2007 depends on customer environment

Dedicated AD resource criteria for Exchange 2007

Is there a performance issue with competing applications?32-bit vs. 64-bit DCs – number of mailboxesMesh vs. Hub and Spoke replication architectureNumber of sites with Exchange Servers <= 5

AD Site Requirements

Using a dedicated AD SiteFully-meshed replication architectures—no special considerationsHub and Spoke environments—dedicated site placement may preclude site from backoff path calculation

Distributed Exchange Sites

A B

CE

D

A1

A2

A3 B1

B2

B3

A B

Directory Replication Hubs

Branch or distributed locations

Dedicated AD sites for Exchange

Deploying Dedicated AD SitesLimited number of Exchange sites

(<=5)Alter AD replication to include the dedicated site as an intermediate replication point on pathsAdd additional site link objects with high AD cost and low msExchCost costing

[PS] C:\> Set-AdSiteLink –id <id> -ExchangeCost <nn>

Hub and spoke replication architecture/distributed Exchange Sites

Collapse the dedicated AD siteUse DNS Priority and Weight to bias DCs

www.microsoft.com/technet/itsolutions/msit/operations/adforexchangenote.mspx

Dedicated AD Site Options

A B

CE

D

A1

A2

A3 B1

B2

B3

A B

msExchCost: 5Site Link Cost: 999

msExchCost: 5

Site Link Cost:

999

msExchCost: 5

Site Link Cost: 999

Option 1: Alter Replication Path

Option 2: Create Exchange Costed Links

Option 3: Collapse Dedicated AD Site and apply DNS Priorities and Weights

Hub SitesForce mail to pass through Hub Transport servers at a defined AD site

Must be a part of the calculated path between source and destination[PS] C:\> Set-AdSite –id <id> –HubSiteEnabled $True

A B

CE

D

A1

A2

A3 B1

B2

B3

A

B

If B is a hub site, mail will never direct to B1 or B3 from any other site

A can never serve as a hub, even if marked as a hub site, because it is not on a direct path between any other sites

Server Deployment

Mailbox Submission Service balances message submission requests (round robin)Exchange Transport Service balances requests between AD Sites (round robin)Transport cannot be deployed onto a SCC, CCR or SCR clustered configurationA single, deterministic path is calculated to deliver a messageEqual cost path arbitration

Hop CountAlphabetic based upon site name

Data Center Resiliency

Not an Exchange Server 2007 design goalExchange Server 2007 RTM Support

Data Center ResiliencyBe aware of possible “Active-Active” configurations

Edge Transport

Transport Role which resides in perimeter networkNot AD-joined—hosts ADAMEdgeSync Service replicates subset of recipient information via one-way push and maintains send/receive connectors with Hub Transport

Subscription based replicationHashed version of organization recipientsSafe Sender List aggregation

Port 25 is only inbound port/connection

Coexistence RoutingExchange 2007 Routing Engine

Understands cost calculation for Exchange 2007 (AD Site Links) and legacy versions (RGC Costs)Attempts to keep messages routed across versions in Exchange 2007 Routing Group as long as possible and will choose to exit the routing group at a legacy server which has lowest legacy path cost possibleOptimizes path within the Exchange 2007 routing group based upon AD Site Topology

Legacy Exchange versions see all Exchange 2007 servers as a single routing group—no cost associated with traversing the Exchange 2007 routing group from a legacy perspectiveRequires RGC between legacy Exchange and Exchange 2007

E2K/E2K3 Mailbox

Routing Group B

Coexistence Examples

E2K/E2K3 Mailbox

Routing Group C

E2K/E2K3 Mailbox

Routing Group A

RGC Cost=20

Exchange 2007 Routing GroupIP Site Link

Cost = 50IP Site

Link

Cost = 75

RG

C

Cost=

10

RGC

Cost=10

RG

C

Cost

=20

Source Destination E2K3.E2K7

RG B AD Site #2 20.50

RG A RG B | RG C 30.100 | 20.75

RG B RG C 20.0

AD Site #1 RG A 10.100

Path #1

Path

#1

IP Site LinkCost =

100

Path

#2

Path #2

Path #3

Path #3

RGC

Cost=

30

RG

C

Cost=

15

Path #4

Path #4

RG

C C

ost=

30

Transition ApproachInside Out vs. Outside In

Inside Out: Affects all sites to a greater extent and creates risk of orphaning RG branchesOutside In: Alleviates most migration issues, but could lead to inefficient mail flow patterns

Link state will not propagate across the Exchange 2007 Routing Group—need to disable Exchange 2003 Link State minor version updates

HKLM\System\CurrentControlSet\Services\RESvc\ParametersDWORD: SuppressStateChangesValue: 1

Do not create islands of Exchange 2000/2003 “hubbed” across Exchange 2007Establish inter-version connectivity centrally first and transition from outside in, on a region-by-region basis

Version Transition

Exchange 2007 Routing Group

Legacy Routing Group

Legacy Routing Group

RGC RGC

RGCHigh Cost

RGC/Existing Hub

Low Cost RGC

Routing Groups vs. AD Sites

Routing Group A

Routing Group B

RG

CExchange 2007 will pick a single path between two AD sites in a deterministic fashion. There is no balancing between paths of equal AD cost. Possible Exchange 2003design considerations

Things to Keep in Mind

Exchange 2000/2003 connector restrictions are not honoredExchange Server 2007 transport only provides SMTP protocolMust have RGC connectors in a legacy Exchange environment Must have IP-based Site Links in ADChoose an approach that will reduce duration of transitionDetermine Public Folder requirements

Public Folders and Routing

Exchange 2007 Servers ignore Exchange 2000/2003 RGCs—rely upon

AD Site topology for referralsExchange 2007 Public Folder servers cannot produce content for OWA

ResourcesTechnical Communities, Webcasts, Blogs, Chats & User Groups (http://www.microsoft.com/communities/default.mspx) survive the transition from Linkstate to Exchange 2007 routing (http://msexchangeteam.com/archive/2006/11/01/430185.aspx)Routing load balancing and fault tolerance (http://msexchangeteam.com/archive/2007/01/04/432069.aspx)Active Directory Site and Connector Selection Algorithms (http://msexchangeteam.com/archive/2006/09/15/428920.aspx)Guidance on Active Directory design for Exchange Server 2007 (http://msexchangeteam.com/archive/2007/03/28/437313.aspx)Exchange Server TechCenter (http://technet.microsoft.com/en-us/exchange/default.aspx?wt.svl=TNlink)

Related Sessions, HOLs, Certifications etc.

List the related resources again

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