Quiz Entry - updated: 2026.07.14
What are PAgP and LACP, and what is the key difference between them?
PAgP (Port Aggregation Protocol) is Cisco-proprietary and LACP (Link Aggregation Control Protocol) is the IEEE standard (802.3ad) — both dynamically negotiate EtherChannel formation between switches.
| Feature | PAgP | LACP |
|---|---|---|
| Standard | Cisco proprietary | IEEE 802.3ad |
| Multivendor | Cisco only | Works across vendors |
| Max ports | 8 active | 16 ports (8 active + 8 standby) |
| Packet interval | Every 30 seconds | Every 30 seconds (slow) or 1 second (fast) |
What they do:
- Dynamically negotiate whether ports should form an EtherChannel
- Check that ports on both sides have compatible configuration (speed, duplex, VLAN (Virtual Local Area Network))
- Manage the channel after formation — handle link additions, removals, and failures
Third option — Static (On mode):
You can also force an EtherChannel without any negotiation protocol. Both sides must be set to on. No PAgP or LACP packets are exchanged, so there's no compatibility checking.
Tip: In multivendor environments, always use LACP. PAgP only works between Cisco devices.
Go deeper:
EtherChannel (Wikipedia) — contrasts Cisco-proprietary PAgP with standards-based LACP (802.3ad).- EtherChannels with LACP (Network Direction) — deeper on LACP's keep-alive link-health monitoring, a real operational edge over PAgP/static bundling.