Full form: Port Aggregation Protocol
Also known as: Port Aggregation Protocol
Quick Definition
Cisco's proprietary EtherChannel negotiation protocol.
PAgP is Cisco's proprietary protocol for negotiating EtherChannel formation. PAgP modes are: Desirable (actively tries to form a channel) and Auto (waits for the other side to initiate). A channel forms if at least one side is Desirable. PAgP only works between Cisco devices. For multi-vendor environments or modern deployments, LACP (IEEE 802.3ad) is preferred.
Auto-Auto does NOT form an EtherChannel with PAgP (neither side initiates). At least one side must be Desirable. PAgP is Cisco-only; use LACP for multi-vendor environments.
PAgP is Cisco's proprietary protocol for negotiating EtherChannel formation. PAgP modes are: Desirable (actively tries to form a channel) and Auto (waits for the other side to initiate). A channel forms if at least one side is Desirable. PAgP only works between Cisco devices. For multi-vendor environments or modern deployments, LACP (IEEE 802.3ad) is preferred.
Auto-Auto does NOT form an EtherChannel with PAgP (neither side initiates). At least one side must be Desirable. PAgP is Cisco-only; use LACP for multi-vendor environments.
PAgP falls under the Switching domain of the 200-301 exam. Understanding it in context with related terms like etherchannel and lacp is essential for answering scenario-based questions correctly.