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Module cdp

flowscope

Module cdp 

Source
Available on crate feature cdp only.
Expand description

CDP (Cisco Discovery Protocol) parser.

Gated by the cdp feature. CDP is the Cisco-proprietary L2 discovery protocol — the LLDP sibling for environments with Cisco gear. Operationally identical signal (asset / rogue-switch / topology visibility), but wire-format-wise completely different:

  • LLDP: EtherType 0x88cc, 7-bit-type / 9-bit-length TLVs.
  • CDP: LLC+SNAP-encapsulated 802.3 frame, dst MAC 01:00:0c:cc:cc:cc, OUI 00:00:0C, PID 0x2000, 16-bit type / 16-bit length TLVs.

§Operational signals

  • Asset discovery on Cisco infrastructure: Device-ID, Platform, Software-Version, Capabilities, Mgmt-Address.
  • Topology mapping: Port-ID + Device-ID identifies the peer port of the directly-connected switch.
  • Rogue-switch detection: a CDPDU on a port where one isn’t expected (or a Device-ID that doesn’t match the asset register) is a high-confidence MITM signal.

§Wire shape

  • parse — pure CDPDU payload (after the LLC+SNAP+OUI+PID header). Use when the consumer has already validated the encapsulation.
  • parse_frame — full Ethernet frame; validates the reserved Cisco multicast dst MAC + LLC + SNAP + OUI + PID sequence.
  • CdpParser — stateless marker.

Issue #25 (0.18).

Structs§

CdpAddress
One decoded CDP address-block entry.
CdpCapabilities
CDP capability bits (TLV 0x0004). Source: Cisco’s public CDP technical reference.
CdpMessage
One parsed CDPDU. Almost every CDPDU carries Device-ID; the rest of the TLVs are optional. Bounded at the operationally-interesting field set — vendor / experimental TLVs aren’t surfaced (file follow-ups if needed).
CdpParser
Stateless CDP marker, mirroring ArpParser / LldpParser.

Enums§

ParseError
Failure mode for the parse* functions (issue #85).

Constants§

CDP_DST_MAC
CDP destination multicast MAC.
CDP_OUI
CDP OUI inside the SNAP header.
CDP_PID
CDP protocol ID inside the SNAP header.

Functions§

parse
Parse a CDPDU payload (post the LLC/SNAP/OUI/PID header).
parse_frame
Parse a full Ethernet frame whose payload is a CDPDU.