Which two aspects must be considered before the network design is finalized?

A metro service provider is planning Resilient Ethernet Protocol for his backbone.

Which two aspects must be considered before the network design is finalized? (Choose two.)
A . Two Resilient Ethernet Protocol segments can be connected redundantly at two points. One connection will be blocked, using the Spanning Tree Protocol defined in IEEE 802.1
C . UniDirectional Link Detection Protocol can be enabled on Resilient Ethernet Protocol interfaces to detect unidirectional failures.
D . The guaranteed convergence recovery time is less than 50 ms for the local segment.
E . A Resilient Ethernet Protocol segment is limited to a maximum of seven devices.
F . VLAN load balancing for optimal bandwidth usage is supported in any Resilient Ethernet Protocol segment.

Answer: B,E