What is the Relationship between LACP and PAgP?
LACP and PAgP have a mutually exclusive relationship, that is, they cannot be used simultaneously on the same port. If a port is configured to use LACP, it cannot use PAgP, and vice versa. If a port that uses LACP is connected to a port that uses PAgP, then link aggregation will not be formed, because LACPDU and PAgPDU frames cannot recognize each other.
LACP and PAgP also have a complementary relationship, that is, they can be used interchangeably on different ports. If the network device supports both protocols, then different ports can be configured to use LACP or PAgP, depending on needs and preferences. For example, ports connected to network devices from different vendors can use LACP, while ports connected to Cisco devices can use PAgP.
When to Use LACP or PAgP?
The choice between LACP or PAgP depends on several factors, including:
- Network device compatibility. If the network device only supports LACP, then LACP must be used. If the network device only supports PAgP, then PAgP should be used. If the network device supports both protocols, then the choice can be adjusted to your needs and preferences.
- Network device vendors. If the connected network device is from a different vendor, then LACP must be used, as LACP is a standard protocol that can work on network devices from different vendors. If the connected network device is from Cisco, then PAgP can be used, because PAgP is a proprietary protocol that can only work on Cisco devices that support it.
- Number of ports needed. If the number of ports required for link aggregation is more than 8, then LACP must be used, because LACP can support up to 16 ports in a single link aggregation. If the number of ports required for link aggregation is no more than 8, then PAgP can be used, because PAgP can support up to 8 ports in a single link aggregation.
Conclusion
LACP and PAgP are two protocols used to combine multiple physical ports into one logical port, referred to as link aggregation. The purpose of link aggregation is to increase bandwidth, redundancy, and network availability.
LACP is a standard protocol defined by IEEE 802.3ad, while PAgP is a proprietary protocol developed by Cisco. LACP and PAgP have some differences, among others in terms of compatibility, frame format, mode of operation, and number of ports supported.
LACP and PAgP also have a mutually exclusive and complementary relationship. LACP and PAgP cannot be used simultaneously at the same port but can be used interchangeably in different ports.
The choice between LACP or PAgP depends on several factors, including network device compatibility, network device vendor, and number of ports needed.