Ethernet Automatic Protection Switching
Ethernet Automatic Protection Switching (EAPS) is used to create a fault tolerant topology by configuring a primary and secondary path for each VLAN.
It was invented by Extreme Networks. The idea is to provide highly available Ethernet switched rings (commonly used in Metro Ethernet). Other implementations include Ethernet Protection Switching Ring (EPSR[1]) by Allied Telesis.
Operation
A ring is formed by configuring a Domain. Each domain has a single "master node" and many "transit nodes". Each node will have a primary port and a secondary port, both known to be able to send control traffic to the master node. Under normal operation only the primary port on the master node is used to avoid loops (the secondary port is blocked for all non-control traffic). When there is a link down situation, the devices that detect the failure send a control message to the master and the master unblocks the secondary port and instructs the transits to flush their databases.
The same switch can belong to multiple domains and thus multiple rings. However, these act as independent entities and can be controlled individually.
EAPS v2
EAPSv2 is configured and enabled to avoid the potential of super-loops in environments where multiple EAPS domains share a common link. EAPSv2 works using the concept of a controller and partner mechanism. Shared port status is verified using health PDUs exchanged by controller and partner. When a shared link goes down, the configured Controller will open only one segment port for each of the protected VLANs, keeping all other segment ports in a blocking state.
See also
References
External links
- RFC 3619 (EAPS)
- ITU-T G.8031/Y.1342
 | This computing article is a stub. You can help Wikipedia by expanding it. |