CISNTWK-492e. Microsoft Exchange Server 2003 Administration. Chapter Eight Managing Routing and Internet Connectivity

Transcription

1 CISNTWK-492e Microsoft Exchange Server 2003 Administration Chapter Eight Managing Routing and Internet Connectivity 1

2 Objectives Understand SMTP and how it works Understand how Exchange Server 2003 makes use of SMTP Understand how message routing works within an Exchange Server 2003 infrastructure Describe the link state algorithm and how Exchange Server 2003 makes use of it Describe how external messaging is handled within Exchange Server

3 Managing Routing and Internet Connectivity Message routing: process of sending a message to an intended recipient Site: logical grouping of servers using permanent, high-bandwidth connectivity Sites define three boundaries: Single-hop routing, administrative unit, namespace 3

4 Managing Routing and Internet Connectivity Exchange Server 2003 separates boundaries Single-hop routing is defined by a routing group Administration unit is defined by the administrative group Namespace hierarchy exists in Active Directory as a domain 4

5 The Simple Mail Transfer Protocol Simple Mail Transfer Protocol (SMTP) Used to send and receive Designed to work on top of TCP/IP Primary messaging protocol used by Exchange Server 5

6 The Simple Mail Transfer Protocol Protocol: set of rules defining interaction between computers SMTP is made up of several different protocols RFC 2821 specifies interaction between two servers RFC 2822 specifies message header (envelope) elements 6

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9 The Simple Mail Transfer Protocol (continued) Multipurpose Internet Mail Extension (MIME) Describes a message as consisting of many parts Each part could be formatted differently Example: Parts may be audio, video, text SMTP handles only textual (not binary) data Solved by converting binary data to text-like format Conversion process is called uuencode MIME adds six headers to RFC 2822 envelope Three mandatory and three optional headers 9

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13 The Simple Mail Transfer Protocol How MIME works (continued) Concatenates all of the attachments Places message headers between attachments Defines content in attachment (plain text, HTML, etc.) Defines how content t is encoded d for transfer 13

14 The Simple Mail Transfer Protocol (continued) Content type consists of two divisions Top-level media type and corresponding subtype Other types may be specified for proprietary formats Multipart content type Defines message structure with more than one part Each part has its own headers 14

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16 SMTP and Exchange Server 2003 Exchange Server 2003 and SMTP Uses SMTP service provided by Windows 2000/2003 SMTP is the native transport protocol Windows SMTP service Component of Internet Information Services (IIS) Runs as part of Inetinfo.exe 16

17 SMTP and Exchange Server 2003 (continued) Six ways Exchange Server 2003 enhances SMTP service SMTP management is removed from IIS Manager and added to Exchange System Manager Exchange added d support for link state t information Better queuing for improved message delivery, tracking Message categorizer communicates with global catalog Installable File System (IFS) store driver provides access to Exchange store Mail folder moved to \exchsrvr\mailroot\vsi \ i1\ 1\queue 17

18 SMTP and Exchange Server 2003 (continued) Active Directory stores Exchange Server modifications You can configure multiple virtual SMTP servers on each Exchange Server

19 Activity 8-1: Creating SMTP Virtual Servers Time Required: 10 to 20 minutes Objective: Create an SMTP virtual server within Exchange Server 2003 to allow the delivery of messages via SMTP to external SMTP servers Description: Create an additional SMTP virtual server on the back-end server. Reasons for creating an additional SMTP virtual server include adding additional fault tolerance to your environment and allowing your organization to host multiple default domains. 19

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22 Activity 8-2: Configuring SMTP Virtual Server Options Time Required: 10 to 20 minutes Objective: Configure your SMTP virtual server to restrict access to it Description: By default, virtual servers are accessible to all IP addresses, which can present a security risk that could allow your server to be misused. To control use of a virtual server, you can grant or deny access by IP address, subnet, or domain. 22

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24 Understanding Message Routing Underlying message routing subsystem functions Breaks down message processing into parts Key to understanding the big routing picture Messages delivered over the least expensive route Determine route by adding costs configured on routing connectors If the route with the lowest cost is down, the next least expensive route is used 24

25 Routing Groups and Connectors Routing group in an Exchange organization Consists of well-connected Exchange servers Full-time, full mesh connectivity guaranteed Within a routing group, special connectivity is not needed Default eautrouting gconfiguration guato for Exchange geservers Single routing group Named after administrator group Manually add additional routing groups and servers Messages may be routed to other locations External systems Other routing groups in an Exchange organization 25

26 Routing Groups and Connectors (continued) Reasons for configuring alternate routing group Limited capacity/availability of network connections Policy limits or restrictions on the size of messages Need for scheduling the flow of 26

27 Routing Groups and Connectors (continued) Exchange uses one of four connectors for alternate groups: Routing group connector SMTP connector X.400 connector Specialty connector (GroupWise or Lotus Notes) 27

28 Activity 8-3: Installing a Routing Group Connector Time Required: 10 to 20 minutes Objective: Install a routing ggroup connector to provide connectivity between two routing groups Description: Install a routing group connector between two routing groups. The routing group connector will be installed on each bridgehead d server within their respective routing group, and configured appropriately to allow connectivity. 28

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31 Other Transport Methods Three methods of message flow SMTP service Internet or routing group connector Store submission Microsoft Outlook MAPI client or an OWA client MTA (Message Transfer Agent) Uses X.400 connectivity High level descriptions of SMTP message flow: Message first sent to NTFS queue Message then delivered to precategorization queue Message awaits processing by categorizer 31

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33 Other Transport Methods (continued) Messages submitted via store submission or MTA Messages dropped into Exchange store driver Store driver passes message to precategorization queue Message awaits processing by categorizer Message categorizer: collection of event sinks Event sink: script run against messages Activities performed by message categorizer Distribution list expansion conducted Attributes from Active Directory retrieved Message placed in postcategorization queue 33

34 Activity 8-4: Configuring Routing Group Connector Delivery Options Time Required: 10 to 20 minutes Objective: Configure delivery options to deliver large messages during nonpeak hours Description: Configure the delivery options for the new routing group connector. Delivery options control when messages are sent through the connector. One of the key features is the ability to set connection schedules for all messages or messages of different size. 34

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36 Link State Algorithm Routing engine consulted for optimal routes If routing a message internal to the organization DNS query determines address of destination server SMTP service directly delivers the message 36

37 Link State Algorithm If routing a message external to the organization Routing engine determines optimal routes Routing engine utilizes link state algorithm Link state algorithm is the basis for Open Shortest Path First protocol (OSPF) 37

38 Routing Group Master Routing group master is configured in each group Receives link state information Propagates information internally Link state algorithm operates over TCP port 691 Propagates information externally Uses bridgehead server (may be dually configured) Link state algorithm operates over TCP port 25 Maintains i link state t information 38

39 Routing Group Master Two states available for a link: up or down Bridgehead server monitors down links 39

40 Link State Information Link state information held in memory, not disk Other routing ggroup masters may replicate link state Role of Active Directory Routing group information is held in naming partition Definitions of connectors and costs are also held 40

41 Link State Information Link state algorithm references connector by its GUID Conditions where link state propagation has improved Where no alternative path exists Where connections are intermittent or oscillating 41

42 How Exchange Makes Use of Link State Information Illustration with Importers of America: Routing group connects five cities Each site is represented as a distinct routing group Connectors are established among groups Costs are depicted Routing costs play a key role in optimizing message routing Connector with the lowest cost is preferred If the lowest cost connector is down, choose the next lowest 42

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44 How Exchange Makes Use of Link State Information (continued) Scenario when all connections are up: Toronto server sends message to Rio de Janeiro Intermediate hop to San Francisco Lowest cost route: Toronto-San Francisco-Rio 44

45 How Exchange Makes Use of Link State Information (continued) Scenario with link failure between SF and Rio: After three attempts, SF server marks connection down SF server updates link state over TCP port 691 Routing master updates other servers in SF group SF server recalculates alternate route, notifies Toronto Toronto server uses alternate (the direct) path to Rio 45

46 Activity 8-5: Setting Routing Costs for a Connector Time Required: 10 to 20 minutes Objective: Configure routing costs for a connector Description: Configure the routing cost for a connector. Configuring multiple connectors with the same routing cost tells Exchange Server 2003 to distribute ib t the load as evenly as possible among connectors. 46

47 Activity 8-6: Configuring the Retry Intervals for SMTP Virtual Servers Time Required: 10 to 20 minutes Objective: Configure the retry interval for an SMTP virtual server Description: Configure the retry interval on your SMTP virtual server. In Exchange Server 2003, if a message cannot be delivered on the first attempt, t Exchange Server 2003 tries to send it again after a specified time. 47

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49 Using Link State Information to Route Externally External routing is similar to internal routing Evaluate the connector with an address space close to the destination Evaluate costs associated with using those connectors 49

50 Using Link State Information to Route Externally Scenario with three Internet connectors (1) routes addresses based on *.br at a cost of 10 (2) routes addresses based on *.net at a cost of 20 (3) routes all other addresses at a cost of 10 Goal: route to ryan@importsofamerica.br 50

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52 Using Link State Information to Route Externally (continued) Routing process is performed by Exchange Server 2003 Look for connector with similar il address space Determine that connector for *.br is a close match Route message through SMTP connector in Sao Paolo Message is then delivered using Sao Paolo connector 52

53 Using Link State Information to Route Externally (continued) Lowest cost connector is preferred Routing does not fail over to a connector with a less specific address space Example: connector serving *.br does not fail over to * 53

54 Activity 8-7: Installing an SMTP Connector Time Required: 10 to 20 minutes Objective: Provide some perspective on how Exchange Server 2003 routes external SMTP mail; install and configure an SMTP connector. Description: Install an SMTP connector for your Exchange Server 2003 organization. You must define which local bridgehead servers the connector will use as well as the connector scope, message routing technique, and address space. SMTP virtual servers act as local bridgehead servers for SMTP connectors. 54

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56 Activity 8-8: Configuring Delivery Options for SMTP Time Required: 10 to 20 minutes Objective: Configure the delivery options for an SMTP connector Description: Configure the delivery options for an SMTP connector. SMTP connectors have delivery options that determine when messages are sent tthrough hthe connector as well as whether messages are queued for remote delivery. 56

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58 Summary SMTP protocol suite includes RFC 2821 and 2822 RFC 2821 defines interaction between servers RFC 2822 covers the basic elements of a message MIME extends headers of basic SMTP messages SMTP messaging is implemented with virtual servers 58

59 Summary (continued) Routing group is a collection of well-connected servers Alternate routing ggroups handle limited capacity/availability Four connector types: SMTP, routing group, X.400, specialty connectors Link state routing propagates information in near real time Servers use TCP port 691 for internal communication of link state 59

60 Summary (continued) Servers use TCP port 25 for external communication of link state Link state routing improved when no alternative paths exist Link state routing also improved for intermittent connections Routing engine selects connectors with lowest cost sent externally through connector with closest address space 60