Topology Discovery: Difference between revisions
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==Explicit Protocols== | ==Explicit Protocols== | ||
===Cisco Discovery Protocol (CDP)=== | ===Cisco Discovery Protocol (CDP)=== | ||
===Link-Layer Discovery Protocol (LLDP)=== | |||
IEEE Standard 802.1AB-2005. It operates directly atop Ethernet, using protocol number 0x88cc, or over SNAP-encoded LLC with the discriminator aa:aa:03:00:00:00. The LLDP multicast destination address is 01:80:c2:00:00:0e. | |||
===Link-Local Topology Discovery (LLTD) Protocol=== | ===Link-Local Topology Discovery (LLTD) Protocol=== | ||
A [http://msdn.microsoft.com/en-us/windows/hardware/gg463061.aspx Microsoft protocol] native to Windows Vista and supported on Windows XP via add-on. It operates directly atop Ethernet, using protocol number 0x88D9. | A [http://msdn.microsoft.com/en-us/windows/hardware/gg463061.aspx Microsoft protocol] native to Windows Vista and supported on Windows XP via add-on. It operates directly atop Ethernet, using protocol number 0x88D9. | ||
====LLTD Packet Format==== | ====LLTD Packet Format==== | ||
{| class="wikitable" border="1" | {| class="wikitable" border="1" | ||
|- | |||
! Field | ! Field | ||
! Size | ! Size | ||
! Value | |||
|- | |||
| colspan="3" align="center" | '''Ethernet header (14 bytes)''' | |||
|- | |- | ||
| Destination MAC | | Destination MAC | ||
| 6 | | 6 octets | ||
| | |||
|- | |- | ||
| Source MAC | | Source MAC | ||
| 6 | | 6 octets | ||
| | |||
|- | |- | ||
| Protocol | | Protocol | ||
| 2 octets | |||
| 2 | | 0x88d9 in [[Endianness|NBO]] | ||
|- | |||
| colspan="3" align="center" | '''LLTD Demux Header (4 bytes)''' | |||
|- | |||
| Version | |||
| 1 octet | |||
| 1 | |||
|- | |||
| Type of Service | |||
| 1 octet | |||
| | |||
*0: Topology Discovery | |||
*1: Quick Discovery | |||
*2: QoS Diagnostics | |||
|- | |||
| Reserved | |||
| 1 octet | |||
| Must be set to 0 by sender | |||
Must be ignored by receiver | |||
|- | |||
| Function | |||
| 1 octet | |||
| Specific to Type of Service values | |||
|- | |||
|} | |} | ||
==Inferring Topology== | ==Inferring Topology== | ||
==See Also== | |||
* Wireshark's entries for [http://wiki.wireshark.org/LinkLayerDiscoveryProtocol LLDP] | |||
[[CATEGORY: Networking]] | [[CATEGORY: Networking]] | ||