Network Topology: Connectivity Visualized Dennis Morgan Lead Program Manager Network Experience microsoft.com Microsoft Corporation

Session Outline Windows Connect Now Overview Why visualize connectivity? Network map explained Link Layer Topology Discovery (LLTD) explained How LLTD works overall How the LLTD Responder works Demo Call to action

Windows Connect Now The Windows Networking and Device Connectivity Platform Effortless “It Just Works” experience for users Simple protocols, APIs and DLLs for partners and developers Secure and Reliable Built-in security to enable higher user confidence Make reliability a fundamental part of the solution Foundation for the Future Continue enabling compelling new user experiences

Windows Connect Now Programs Technical Guidance Consolidated Licensing Program For questions microsoft.com Access to Technologies

Devices Class APIs (Digital Still Cameras, Portable Media Players, Printers, etc.) Windows Connect Now Technologies IP Network (IPv4, IPv6) WCN Configuration Ethernet/Wireless qWAVE WS-D, UPnP Function Discovery Applications WMC, Media Renderers, MCE MTP/IP, RDP, other Network Topology Windows Connect Now Technologies PnP-X

Why Visualize Connectivity? Users having difficulties setting up their network Users don’t know or want to know how their networks are wired We still have a way to go until networking is truly “plug and play” Users have difficulties troubleshooting issues on their network Multiple points of failure Hubs, Switches, Gateways, APs, Bridges, Cables Requires technical skill set to fix Tedious to check power, connectivity, link integrity to discover issues Remote support effectiveness limited by lack of network connectivity Difficult support experience Takes up time and generates user frustration Cannot properly describe topology to support technicians Erodes customer satisfaction and trust Expensive for vendors to support Blame the issue on the wrong device; may result in product return! The solution is the Network Map and Link Layer Topology Discovery!

Network Map Explained Shows the devices physically connected to the network Provides basic information about the device Device name, manufacturer info, IP address, etc. Keeps history of last known topology per profile to see if things have changed Shows how the devices are connected together What’s plugged into what What’s the path to the Internet What’s the path to other devices on my network Adds diagnostic information on top of topology map to help users resolve issues themselves Shows where the issue is on the network Provides entry point for diagnostic tasks

Network Map Explained Integrated with the Network Explorer Unified location for seeing PCs and network devices How the Network Map gathers information Function Discovery WS-Discovery Universal Plug and Play Link Layer Topology Discovery

Link Layer Topology Discovery Explained Layer 2 protocol for: Discovery and mapping of network devices Performing time-probe QoS tests Does not need IP connectivity to work Consists of a Mapper and a Responder Not all devices need to implement Responder for discovery and mapping to work The more Responders on the network, the better we can map the topology of the network

Value of LLTD Lower support costs Users can troubleshoot issues themselves Users can describe their network topology accurately Enhanced presence in Windows Networking UI Network Explorer Network Map

LLTD Architecture on Windows Longhorn IP Network Map NDIS Mapper Service Mapper Driver Responder Driver Function Discovery Platform OS LLTD Mapper Modules Application LLTD Responder Module Legend :

LLTD Architecture on Network Devices IP UPnP Network Interface Responder Driver WS- Discovery Device OS LLTD Responder Module Legend :

LLTD Mapper and Responder Mapper Service that queries for devices on the network Sends out requests to Responders to run tests Interprets results from Responders to create the topology map Sends topology map information to Network Map for rendering Responder Implemented on network-attached devices Performs tests on the network to Determine what other devices are on the same segment Determine what infrastructure device it is attached to Determine quality of service between devices Four states Quiescent, Hello, Command Loop, Emit

Quiescent State Responder waits for a Mapper to start the mapping process Listens to broadcast frames waiting for a MapBegin After Responder sees a MapBegin frame, it moves to the Hello state to begin association process with a Mapper A Responder can be associated with only one Mapper at a time.

Hello State Responder associates with a Mapper Mapper gets a list of Responders on the network A generation number (unique identifier for the mapping session) is created Responders pay attention to avoid network overload on large networks Subsequent Mappers are told that a mapping session is already occuring on the network After association with Mapper is complete, a Responder moves to the Command Loop state

Command Loop State The Command Loop state is where Responders spend most of their active time Interface is in promiscuous mode Responders execute Emit and Query commands received from a Mapper Emit includes a list of probe tests, each of which requests that the Responder transmit frames with the given source and destination Ethernet addresses Query asks the Responder to return its list of probe information Responders go to the Emit state when they have a valid Emit frame from Mapper

Emit State Each entry from the existing list of Emit requests is serviced in turn A Responder continues to handle incoming protocol frames Drops incoming Emit and Query requests After all the requests are serviced, the Responder returns to the Command Loop state.

Responder State Diagram Hello Command Loop Emit Quiescent

Required Type Length Values (TLVs) HostID Flags Physical Medium IPv4 Address Link Local IPv6 Address (if applicable) Wireless Mode (if applicable) BSSID (if applicable)

Optional TLVs Machine / Device Name Contact Info Friendly Name Manufacturer Name Link Speed RSSI Management URL Icon URL

Demo

Call To Action Implement the LLTD Responder in your device Available under the Windows Connect Now licensing program launching mid-2005 Royalty free What you get Responder protocol spec Reference Responder code Test validation tool

Community Resources Windows Hardware & Driver Central (WHDC) Technical Communities Non-Microsoft Community Sites Microsoft Public Newsgroups Technical Chats and Webcasts Microsoft Blogs

Additional Resources microsoft.com Related sessions TWMO05004 Device and PC Integration with Discovery, Plug and Play, Publication, and Network Explorer TWMO05008 Design Requirements for Residential Gateways and WLAN APs TWMO05011 qWAVE and Quality of Service

© 2005 Microsoft Corporation. All rights reserved. This presentation is for informational purposes only. Microsoft makes no warranties, express or implied, in this summary.