Link Layer Topology Mapper

  

The Link-Layer Topology Discovery Mapper (lltdsvc) service creates a network map, which includes computer and device connectivity information and metadata that describes each computer and device. If this service is disabled, the network map does not function properly.This service is installed by default and its startup type is Manual. When the Link-Layer Topology Discovery. If Link-Layer Topology Discovery Mapper I/O Driver is stopped, the following services cannot start: Restore Default Startup Type for Link-Layer Topology Discovery Mapper I/O Driver. Automated Restore. Select your Windows 10 edition and release, and then click on the Download button below.

Link Layer Topology Discovery (LLTD) is a proprietary link layer protocol for network topology discovery and quality of service diagnostics. Microsoft developed it as part of the Windows Rally set of technologies. The LLTD protocol operates over both wired (such as Ethernet (IEEE 802.3) or power line communication[1]) as well as wireless networks (such as IEEE 802.11).

LLTD is included in Windows Vista and Windows 7. It is used by their Network Map feature to display a graphical representation of the local area network (LAN) or wireless LAN (WLAN), to which the computer is connected. Windows XP does not contain the LLTD protocol as a standard component and as a result, Windows XP computers do not appear on the Network Map unless the LLTD responder is installed on Windows XP computers.[2] LLTD is available for download for 32-bit editions of Windows XP with Service Pack 2 (as a publicly released update)[3] and for Windows XP with Service Pack 3 (as a hotfix by request).[4] LLTD Responder was not released for Windows XP Professional x64 Edition. A 2006 fall update for the Xbox 360 enabled support for the LLTD protocol.[5]

Being a link layer (or OSI Layer 2) implementation, LLTD operates strictly on a given local network segment. It cannot discover devices across routers, an operation which would require Internet Protocol level routing.

Link Layer Topology Discovery in Windows Vista consists of two components. The LLTD Mapper I/O component is the master module which controls the discovery process and generates the Network Map. Appropriate permissions for this may be configured with Group Policy settings. It can be allowed or disallowed for domains, and private and public networks. The Mapper sends discovery command packets onto the local network segment via a raw network interface socket. The second component of LLTD are the LLTD Responders which answer Mapper requests about their host and possibly other discovered network information.

In addition to illustrating the layout of a network with representative icons for the hosts and interconnecting lines, each device icon may be explored to produce a popup information box summarizing important network and host parameters, such as MAC address and IP address (both IPv4 and IPv6). Icons are labeled with the hostnames (or first component of their fully qualified domain names), or a representative name of the function of the device, e.g., 'gateway'. If the device has reported the presence of a management Web interface, clicking on the icon will open a HTTP session to the host.

The LLTD responder for Windows XP only supports reporting of IPv4 addresses and not IPv6.

A royalty freeLinux sample implementation of the LLTD responder is available from Microsoft as part of the Windows Rally Development Kit. Using LLTD specifications requires signing a Microsoft Windows Rally license agreement.[6]

There also exists a Perl implementation, using Net::Frame, available via CPAN[7]

See also[edit]

  • Link Layer Discovery Protocol - same aim (and layer) but IEEE standard protocol.
  • Cisco Discovery Protocol - Similar end as LLTD which is based on CDP.

References[edit]

Topology

Link Layer Topology Discovery Mapper Security

  1. ^Marcos, Jorge (9 May 2009). 'Using Microsoft Windows LLTD with DS2 powerline networks'. DS2 Blog. DS2 Corporation (www.ds2.es). Retrieved 18 July 2010.
  2. ^'Network Map in Windows Vista does not display computers that are running Windows XP (Revision 7)'. Microsoft Support. Microsoft Corporation. 1 July 2010. Retrieved 18 July 2010.
  3. ^'Download details: Link Layer Topology Discovery (LLTD) Responder (KB922120)'. Microsoft Download Center. Microsoft Corporation. 21 November 2006. Retrieved 18 July 2010. Supported Operating Systems: Windows XP with Service Pack 2
  4. ^'Hotfix Request: 922120'. Help and Support. Microsoft Corporation. Retrieved 21 August 2011.
  5. ^Windows Networking Development Team. 'Xbox 360 Fall Update Includes LLTD'. MSDN Blogs. Retrieved May 19, 2015.
  6. ^'Link Layer Topology Discovery Protocol Specification'. Windows Hardware Developer Central. Microsoft Corporation. 15 September 2006. Retrieved 18 July 2010.
  7. ^'Patrice Auffret / Net-Frame-Layer-LLTD'. CPAN (search.cpan.org). 15 March 2007. Retrieved 18 July 2010.

External links[edit]

  • Link Layer Topology Discovery Protocol Specification and license
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Link_Layer_Topology_Discovery&oldid=738699380'

Microsoft Link Layer Topology Discovery

Like other administrators and users, I’m happy for the release of Windows 7 and Server 2008 R2. While Windows 7 is touted as more of a client operating system revival from the poor reception that Vista had on the market, Windows Server 2008 is a less controversial and natural upgrade of the server operating system. Both products were released at the same time and have quite a bit in common. One item that both have in common is support for both IPv4 and IPv6 running on default installations. Both also have two new networking protocols running: the Link-Layer Topology Discovery Mapper I/O Driver and Link-Layer Topology Discovery Responder.

Thus far, I’ve simply turned off IPv6, both of the new protocols, and sometimes the QoS Packet Scheduler depending on my mood. Regarding the two new protocols, what are they and what do they do?

Link Layer Topology Discovery Mapper

Link-Layer Topology Discovery

The Link-Layer Topology Discovery (LLTD) is a component of the Windows networking implementation that allows computers and other devices to be represented on a map. Windows Vista, Windows Server 2008, and Windows 7 computers can natively populate the Network Map. This is visible in the Network and Sharing Center by selecting See Full Map. Each computer that is discovered can be displayed in this map. Settings that go for each type of network (public, home, work, etc.) dictate behavior for these networks. Somewhat unintuitively, if a network is set to a private-class network, the default settings allow for LLTD operation. If the protocols are removed from the networking stack, LLTD will not work.

The two components for LLTD are the responder and the mapper I/O driver. These components work together to populate and enumerate the maps. Figure A shows a map populated on my private network for two LLTD-enabled systems.Figure A

This shows that W-RWV2 and S-RWV3 are on different switches (which they are) and are connected to the same Internet uplink. I mentioned earlier that this service is usually not enabled, and the systems at the bottom are a mix of Windows XP, Server 2003, and Linux systems. For Windows XP Systems, they can be enumerated in the LLTD maps. Be sure to check this post by Greg Shultz to enable LLTD on XP.

Uninstall The Link-layer Topology (mapper I/o Driver And Responder) Protocols

In my networking practice, I haven’t used this feature and disable it on servers. I tend to rely on DNS and networking tools to get from point A to B. Do you see LLTD as a benefit in your networking requirements? If so, share your comments below.