Key Aspects of Resilient Ethernet Protocol for Metro Service Providers
Question
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.)
Answers
Explanations
Click on the arrows to vote for the correct answer
A. B. C. D. E.BE.
Resilient Ethernet Protocol (REP) is a proprietary protocol developed by Cisco Systems that provides rapid convergence and high availability for Ethernet networks. Before finalizing the network design with REP, there are several aspects that need to be considered.
The two aspects that must be considered are:
UniDirectional Link Detection Protocol (UDLD): UDLD is a protocol that detects unidirectional failures in fiber-optic and copper Ethernet links. UDLD is useful when REP is used in a topology where there are redundant links, as it ensures that both links are working correctly. By enabling UDLD on REP interfaces, any unidirectional failures can be quickly detected, and the affected link can be shut down to prevent any data loss or network disruption.
Convergence Recovery Time: Convergence recovery time is the time it takes for the network to recover after a failure. REP provides fast convergence and high availability by detecting link failures and rerouting traffic within milliseconds. The guaranteed convergence recovery time for the local segment should be less than 50 milliseconds. If the convergence recovery time is longer than 50 milliseconds, it may affect the network's performance and cause downtime.
The other options given in the question are:
A. Two REP segments can be connected redundantly at two points. One connection will be blocked, using the Spanning Tree Protocol defined in IEEE 802.1: This statement is partially correct. REP segments can be connected redundantly, but instead of using the Spanning Tree Protocol, REP uses a blocking mechanism to prevent loops in the network.
D. A REP segment is limited to a maximum of seven devices: This statement is also incorrect. A REP segment can support up to 100 devices.
E. VLAN load balancing for optimal bandwidth usage is supported in any REP segment: This statement is incorrect. REP does not support VLAN load balancing. REP is primarily designed to provide fast convergence and high availability in Ethernet networks.
In summary, when designing a network with REP, it is essential to consider the convergence recovery time and enable UDLD to detect any unidirectional failures.
