Routing and Remote Access Service for Windows nt server

RIP version 2 (and version 1) for IP

A RIP router maintains a routing table and periodically sends announcements to inform other RIP routers on the network of the networks it can reach. RIP also announces when it can no longer reach networks. RIP version 1 uses IP broadcast packets for its announcements. A later enhancement, RIP version 2, uses IP multicast packets for its announcements.

Each entry in a RIP routing table provides information about the entry, including the ultimate destination address, the next hop on the way to the destination, and a metric which indicates the distance in number of hops to the destination, its "cost" to the router. Other information can also be present in the routing table, including various timers associated with the route.

Initially, each router’s table includes only the links to which it is physically connected. A router depends on periodic updates from other routers to keep current information on what routes are reachable through them. RIP maintains only the best route to a destination through broadcast messages at 30-second intervals, or triggered updates. Triggered updates occur when the network topology changes and routing update messages are sent which reflect those changes. For example, when a router detects a link failure or a router failure, it recalculates its routes and sends routing update messages (triggered updates). Each router receiving a routing update message that includes a change updates its tables and propagates the change.

The biggest advantage of RIP is that it is extremely simple to configure and deploy. The biggest disadvantage of RIP is that as networks grow larger in size, the periodic announcements by each RIP router cause excessive traffic on the network. RIP is widely deployed in networks with up to 50 servers or so, but most larger organizations use other routing protocols.

OSPF

Developed in response to the inability of RIP to serve large, heterogeneous internetworks, OSPF is a link-state protocol based on the Shortest Path First (SPF) algorithm. This algorithm computes the shortest path between one source node and the other nodes in the network. Various industry sources indicate that about 35% to 40% of the routed networks in place today make use of OSPF and this number is growing.

Instead of exchanging distances to destinations like RIP routers do, OSPF routers maintain a “map” of the network that is updated after any change in the network topology. This map, called the link-state database, is used to compute the network routes, which must be computed again after any change in the topology. From this computation, the router derives the next hop for the destination, that is, the next router to which the data should be sent and the link that should be used for reaching this next router. Network changes are propagated or flooded across the entire network to ensure that each copy of the database is accurate at all times.

Because OSPF routers keep an overview of the network from the perspective of any router, some of the problems that are inherent in RIP (such as loops) are eliminated.

The new service’s router OSPF implementation supports the following features:

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  Route filters for controlling interaction with other routing protocols
  
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  Dynamic reconfiguration of all OSPF parameters
  
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  Coexistence with RIP
  
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  Dynamic addition and deletion of interfaces
  

DHCP Relay Agent for IP

Additionally, Windows Internet Name Service provides a distributed, dynamically updated database of host names mapped to IP addresses. This allows users to use friendly host names instead of IP address to locate network resources. Microsoft Domain Naming System (DNS) server running under Windows NT Server 4.0 is a Request For Comment (RFC)-compliant DNS name server that is used to manage and administer DNS services on a TCP/IP network. Microsoft DNS server supports RFC’s 1033, 1034, 1035, 1101, 1123, 1183, and 1536 and is also compatible with the Berkeley Internet Name Domain (BIND) DNS implementation.

Integration of DNS and Windows Internet Name Service services is an important feature that allows inter-operability between non-Microsoft and Windows-based TCP/IP network clients. DNS and Windows Internet Name Service integration provides a method to reliably resolve name queries for Windows-based computers that use dynamic (DHCP-based) IP addressing and NetBIOS computer names. Windows NT Server 4.0 allows ease-of-administration with the graphical DNS Manager that allows one to manage local and remote Microsoft DNS servers and database files.

RIP and SAP for IPX

RIP for IPX is a simple broadcast protocol used to exchange IPX network routes across a network. This protocol announces routes over each network segment. It is configured periodically so that the routing information kept in the routers is current. Various industry sources indicate that about 15% of the routed networks in place today make use of RIP and SAP for IPX and this number is growing.

RRAS supports network route filters, which enable selective announcements and reception of network routes. RRAS also enables configuration of the timers used for route announcements (for example, the periodic announcement timer).

The Service Advertising Protocol allows nodes that provide services, such as file servers and print servers, to advertise their addresses and the services they provide.

IPX routers send periodic SAP broadcasts to keep all routers on the internetwork synchronized. By default, this is set to every 60 seconds. Routers also send SAP update broadcasts whenever they detect a change in the internetwork configuration.

The implementation of IPX by Windows NT Server (NWLink IPX/SPX Compatible Protocol [NWLink] ) conforms to the Novell IPX Router Specification.

Static Routing

Routing APIs

Works with Industry Standard LAN and WAN Cards

Because RRAS runs on Windows NT Server 4.0, it can enable internetworking using any of the 2,000 LAN and WAN cards that have earned the Windows NT Compatible logo. This provides great customer choice.

Enhancing Remote Access

Routing and Remote Access Server brings new enhancements to what was already a powerful remote access platform. New features such as Extensible Authentication Protocol, Bandwidth Allocation Protocol, and RRAS User Profiles bring new power and flexibility to the platform in the Windows NT 5.0 time frame. The remote access component of offers an array of connectivity options including analog, ISDN, frame relay, T1, X.25, and even the Internet. The RAS APIs make it easy for third-parties to create value-added solutions. Here is a brief summary of the remote access features included with RRAS:

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  Auto-dial and Auto Logon Dial
  
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  Demand Dial Routing
  
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  Authentication with PAP, CHAP, and MS-CHAP
  
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  Extensible Authentication Protocol (EAP) – new in Windows NT 5.0
  
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  RAS User Profiles
  
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  Encryption
  
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  Point-to-Point Tunneling for Client-to-Server
  
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  Point-to-Point Tunneling for Server-to-Server
  
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  Restartable File Copy
  
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  PPP Multi-Link
  
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  Bandwidth Allocation Protocol (BAP) – new in Windows NT 5.0
  
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  RAS Idle Disconnect
  

Auto-dial and Auto Logon Dial

The Windows operating system can map and maintain an association between a Dial-Up Networking entry and a network address to seamlessly integrate Dial-Up Networking with files and applications. This means if a user double-clicks on an icon to open a file that is only accessible over the dial-up connection, Dial-Up Networking will automatically initiate the call. This is a Windows NT 4.0 RAS feature that is retained in RRAS.

Demand Dial Routing

Routing and Remote Access Service supports on-demand dialing over any variety of WAN links, including via the Internet with Point-to-Point Tunneling, eliminating the need for continuous, “nailed-up” connections. As a result, demand dial provides significant cost-savings.

Since a PPTP or a Layer 2 Tunneling Protocol (L2TP) tunnel is just another connection, a Windows NT-based server can route packets over a demand-dial tunnel connection that it initiates as a client to a remote tunnel server. Once the connection is established, traffic from one network is routed over a tunnel connection through a tunnel server onto another network.

Authentication – PAP, CHAP, and MS-CHAP

Routing and Remote Access Service supports Password Authentication Protocol (PAP), Shiva-PAP, Challenge Handshake Authentication Protocol (CHAP), MS-CHAP, as well as support for RADIUS authentication servers.

Extensible Authentication Protocol

The Extensible Authentication Protocol allows new authentication methods to be used with RAS, something that is especially important for the deployment of token card security mechanisms. EAP is the interface that allows third-party authentication modules to plug into the Microsoft Windows NT RAS PPP implementation. Microsoft is adding support for EAP to RRAS in the Windows NT 5.0 time frame.

EAP was proposed to the IETF as a PPP authentication protocol to allow for the authenticator to request more information about the peer before determining the specific authentication mechanism. This is accomplished by postponing this decision from the Link Control Protocol (LCP) phase to the Authentication phase.

RRAS User Profiles

Routing and Remote Access Service will work with the Windows NT Server 5.0 Active Directory to store remote access attributes and profiles for each user. Network managers will be able to assign users to either predefined or customized profiles with system use parameters. Administration will be simplified with user object profiles edited from the Microsoft Management Console (MMC) of Windows NT Server 5.0. In addition to general profile categorizations, such as by workgroup, the system stores information specific to each user, with a pointer to the profile.

Encryption

Routing and Remote Access Service supports 40-bit RSA RC4 encryption. North American customers can also use 128-bit encryption for RAS, which has been made available with Windows NT Server 4.0 Service Pack 2 and later Service Pack releases.

Point-to-Point Tunneling for Client-to-Server

Routing and Remote Access Service continues to support Point-to-Point Tunneling support offered initially in Windows NT 4.0 by enabling remote –client computers to connect to an enterprise network using a secure, encrypted tunnel via the Internet. RRAS with Windows NT Server 5.0, will also support Layer 2 Tunneling Protocol for such client-to-server remote connections.

Point-to-Point Tunneling for Server-to-Server

Routing and Remote Access Service extends the Point-to-Point Tunneling support offered initially in Windows NT 4.0 by enabling remote networks - not just remote clientsto connect using a secure, encrypted tunnel. And as earlier noted, RRAS with Windows NT Server 5.0, will also support Layer 2 Tunneling Protocol. Tunneling enables branch offices to be connected to a corporate network via the Internet rather than via more expensive leased line arrangements. This new use of the Internet as a Virtual Private Network (VPN) can provide big cost savings compared to traditional WAN link alternatives.

Restartable File Copy

Restartable File Copy automatically begins re-transferring a file upon re-connection whenever the RAS connection has been lost. This removes the frustration of losing a connection during a file transfer. Restartable File Copy addresses these problems by remembering the status of the file transmission and continuing the transfer from that point upon reconnection.

Multi-Link PPP

RRAS retains a compelling communications features first offered with RAS in Windows NT Server 4.0 – Multi-Link PPP. Multi-Link PPP allows the bandwidth of two or more modems and/or ISDN lines to be combined to create a single virtual information pipeline. Multi-link PPP supports the simultaneous transfer of data across parallel connections which effectively delivers scaleable bandwidth for maximum efficiency. This feature can be used for both remote client-to-server connections as well as for remote server-to-server connections. In addition, tunneled connections with PPTP or L2TP can be run over Multi-Link PPP connections so the feature provides a great deal of flexibility.

Figure 1. Multi-Link PPP – delivering the bandwidth of two or more analog or digital links.

The Multi-Link PPP support provided by RRAS is based on the IETF standard RFC 1717.

Bandwidth Allocation Protocol

Routing and Remote Access Service will introduce the Bandwidth Allocation Protocol (BAP) in the Windows NT 5.0 timeframe. BAP brings additional efficiencies to Multi-link PPP by dynamically adding or dropping additional links to accommodate traffic flow.

BAP is especially valuable to operations that have carrier charges based on bandwidth utilization. The network manager uses a simple graphical user interface to set the parameters at which multi-link lines are dropped or added. For example, a manager could set the system so that an extra line was dropped if link utilization dropped below 50 percent for more than 10 seconds. Likewise, the system can be set to add a line if bandwidth utilization goes above 50 percent (or whatever value the network manager chooses) for more than perhaps 20 seconds. Because ISDN lines can be added nearly instantaneously BAP provides a very efficient mechanism for controlling connection costs while dynamically providing optimum bandwidth.

RAS Idle Disconnect

This feature automatically terminates your connection to a remote client or to a remote server after a certain period of time if there has been no activity over the remote dial-up communications link. network administrator can specify the amount of time before this feature is activated. This is a Windows NT 4.0 feature that is retained in RRAS.

Managing Routing and Remote Access Service

Routing and Remote Access Service and Windows NT Server provide a platform rich in management features which can be used to create great value-added third-party products. Management features include:

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  Management and User Interface APIs
  
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  Graphical User Interface
  
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  Wizard for Demand Dial Routing Set-Up
  
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  Scriptable, Command line User Interface
  
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  Remote Manageability
  

Management and User Interface APIs

Routing and Remote Access Service provides for ease of administration with both an intuitive graphical user interface and a command-line user interface. A full set of APIs make RRAS management extensible, a great example of the potential for third-party development.

The built-in management features and APIs make it easy to deploy RRAS in existing or new network environments. RRAS supports Simple Network Protocol (SNMP) MIB II so RRAS can be managed from an SNMP console. RRAS running on a Windows NT Server platform can appear, act, and be managed like many other routers in an organization. This allows RRAS to interoperate with existing networking systems. SNMP standards allow devices from different companies to be administered from a central point, such as from an HP OpenView console.

Graphical User Interface

RRAS includes a comprehensive, intuitive graphical user interface that provides a wide range of monitoring and administrative functions for all routes, LAN or WAN interfaces, packet filtering features, and more.





Figure 2. The graphical user interface enhances administration.

RRAS supports administrative screens that are consistent with other standard Windows GUI approaches, including support for right clicking on the mouse for additional control and a setup wizard.

Common administrative tasks that can be performed through the simple graphical user interface include:

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  Adding a demand-dial interface
  
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  Granting RAS clients dial-in permissions
  
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  Adding a routing protocol
  
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  Adding interfaces to a protocol
  
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  Deleting interfaces from a protocol
  
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  Managing remote access servers
  

Wizard for Demand Dial Routing Set-Up

The most challenging set-up and configuration task that emerged from the initial “Steelhead” technical beta program involved the process of setting up a demand dial interface. In fact, this particular task generated the highest number of support calls in that stage of the beta program.

Microsoft addressed the issue by developing a Demand Dial Interface Wizard.

Figure 3. The new Routing Demand Dial Interface Wizard makes set-up a snap.

This wizard makes setting up a demand dial interface quick and easy with RRAS. The wizard prompts the user to type in or check off relevant information then uses that information to configure the service.

Scriptable, Command line User Interface

Many network managers are more comfortable using a command-line interface to manage their network infrastructure, especially in multi-site situations. RRAS supports command-line interface control, including support for scripting.

RRAS provides the routemon scripting utility, which network administrators can use to configure interfaces, routing protocols, filters, and routes for routers running the service. Routemon also displays the configuration of a currently running router service on any computer. The utility also has a scripting feature that can be used to run a collection of commands in batch mode against a specified router.

Figure 4. Routemon allows command-line management and scripting.

Remote Manageability

RRAS’s GUI controls and command-line controls can be used to enable enterprise network management from a central location, remote site, or from mobile workstations. The service’s GUI controls are remotely enabled via Remote Procedure Calls. Command line admin support is remoteable via Telnet.

Securing Network Communication

Network security is a top priority item for any network administrator. Many organizations rely on routers to provide an important measure of security at the point where their internal networks come in contact with the outside world. This security can also be used within an organization’s network to maintain a higher degree of security for certain portions of a network -- for example, a human resources or legal. Routing and Remote Access Service provides a range of security features including:

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  IP Packet Filtering
  
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  IPX Packet Filtering
  
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  RADIUS Client RFC 2058 Compliant
  
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  Works with Microsoft Proxy Service
  
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  Robust Windows NT Server Security
  

IP Packet Filtering

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  Routing and Remote Access Server supports a variety of inbound and outbound packet filtering features, which provide an important measure of network security.
  

Figure 5. Setting up packet filtering is quick and easy with RRAS.

Filtering options include:

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  TCP Port
  
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  UDP Port
  
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  IP protocol ID
  
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  ICMP Type
  
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  ICMP Code
  
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  Source Address
  
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  Destination Address
  

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  TCP Established
  

RRAS packet Filters are configured on an exception basis. Filters can be configured to pass only packets from routes specified by the network manager or configured to pass everything except packets from specified routes. Managing the packet filtering is made easy with GUI-based tools.

IPX Packet Filtering

RRAS supports a similar level of packet filtering for IPX packets. IPX filtering options include:

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  Source Address
  
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  Source Node
  
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  Source Socket
  
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  Destination Address
  
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  Destination Node
  
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  Destination Socket
  
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  Packet Type.
  

RADIUS Client RFC 2058 compliant

RRAS allows a server PC running Windows NT Server to act as a Remote Authentication Dial-In User Service (RADIUS) client to a RADIUS server, providing expanded choice for authentication. RADIUS, a dialup authentication and accounting protocol commonly used by Internet Service Providers, offers another security option that complies with IETF RFC 2058. With this new RADIUS client support, an ISP administrator can elect to use Windows NT Server domain-based database for user authentication or can instead elect to use some other RADIUS server database to perform the authentication.





Figure 6. RADIUS Authentication or Windows NT domain authentication can be used.

Integration with Microsoft Proxy Server

The packet-layer security of Routing and Remote Access Service can be combined with the multi-layered security and Web caching performance of Microsoft Proxy Server to provide an even higher level of network security and performance.

Microsoft Proxy Server 2.0 is a unique product combining the security of a firewall with the high performance and cost savings of a Web cache server, in one easy-to-use, affordable package. Microsoft Proxy Server is a great solution for easy and secure Internet access as well as for Intranet support.

Because the Routing and Remote Access Service runs on an industry standard PC platform running Windows NT Server 4.0, an organization can install and use Microsoft Proxy Server on the same server running RRAS. This combination of server-based routing and Microsoft Proxy Server provides a full spectrum of security and performance for organizations of virtually any size.

Robust Windows NT Server Security

Routing and Remote Access Service and Microsoft Proxy Server inherit all the built-in security features that make Windows NT Server such a secure, scalable platform. RRAS supports the authentication and encryption provided in Windows NT Server 4.0, extending these resources for use with routing.

As noted earlier, RRAS supports bulk data encryption using RSA RC4 and a 40-bit or 128-bit session key. The key is negotiated at PPP connect time between the RAS client or Windows NT Server PC running RRAS on one end and the Windows NT Server-based PC on the other end. The service also supports Password Authentication Protocol (PAP), Shiva PAP, Challenge Handshake Authentication Protocol (CHAP), and the Microsoft Challenge Handshake Authentication Protocol (MS-CHAP)algorithms.

Summary

Routing and Remote Access Service makes Windows NT Server a better than ever platform for deploying a broad array of internetworking solutions. And the huge movement toward the IP standard means the release of RRAS comes at an extraordinarily opportune time for ISVs, IHVs, system integrators, VARs, and network managers involved in creating internetworking solutions

With older networks being re-engineered and with an unprecedented demand for branch office communications, edge routing, VPNs, remote access, firewalls, and other internetworking deployments, third parties can use the flexibility, robustness and scalability of RRAS to meet booming customer needs.

System integrators and network managers can combine the power of RRAS with other Windows NT Server products such as Microsoft Proxy Server, Internet Information Server, and the BackOffice family of applications to create turn-key, single-box solutions for branch offices.

RRAS capabilities are enhanced by the addition of Extensible Authentication Protocol, Bandwidth Allocation Protocol, and RRAS User Profiles in the Windows NT Server 5.0 time frame, along with other core communications enhancements in the operating system.

Companies offering solutions based on today’s RRAS platform will also be able to capitalize on RRAS and related enhancements in the Windows NT 5.0 time frame to continue offering innovative, value-added internetworking solutions for a wide range of customers.

For More Information

For more information on or to download the Routing and Remote Access Service Update, please see: http://www.microsoft.com/ntserver/info/Routing&RAS.htm.

To download the RRAS Software Developer Kit, please see the Windows NT 5.0 Professional Developer Conference CD or Web-based materials. Here is the URL: http://www.microsoft.com/pdc.

For information on Microsoft’s communications and telephony offerings, please see: http://www.microsoft.com/ntserver/iinfo/ntcomm.htm.

For more information regarding Microsoft Proxy Server 2.0, please see http://www.microsoft.com/proxy.

To see a list of the wide variety of LAN and WAN cards that have earned the Windows Compatible logo and, thus, will work with RRAS, please see the Windows Hardware Compatibility List for Windows NT Server 4.0 here: http://www.microsoft.com/hwtest.

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