Summary Comparing VPLS and IPLS
VPLS has one big advantage over IPLS: It provides multiprotocol, multipoint, emulated LAN transport, whereas IPLS provides IP-only multipoint emulated LAN transport.
IPLS, on the other hand, has a number of advantages over VPLS:
- Because unicast packets are transported over IP Layer 2 pseudowires, there is less packet overhead (packets are smaller) because unicast packets are transported over the unicast pseudowires between PE devices.
- There is less processing overhead for an IPLS PE device than there would be for a corresponding VPLS PE device. This is because an IPLS PE device performs a less-complex set of functions than a VPLS PE device.
- Unknown unicast frames (those unicast frames whose destination MAC address is unknown to a PE device) are not flooded in an IPLS as they would be in a VPLS.
- The risk of loops developing in an IPLS is much less than the risk of one developing in a VPLS because IPLS PE devices reject the advertisement of duplicate MAC addresses from peer PE devices.
Finally, it is worth noting that when CE devices are dual homed in IPLS, the connections must be to be to separate IPLS instances (on different IP subnets). Failover between connections can then be achieved using mechanisms such as those provided by dynamic routing protocols.