Which factor is most important?

Heartbeats are used to maintain the high-availability status of an application.

Which factor is most important?

A. Bandwidth

B. Latency

C. Routing

D. Round-trip time

View Answer

Answer: D

Explanation:

From:

http://www.cisco.com/c/en/us/td/docs/wireless/controller/7-4/configuration/guides/consolidated/ b_cg74_CONSOLIDATED/b_cg74_CONSOLIDATED_chapter_01111101.html https://books.google.com.hk/books?id=YLHvHGGx5AEC&pg=PT66&lpg=PT66&dq=wlc+heatbeat+round +trip+time&source=bl&ots=ClFsWOm0RH&sig=5NO_zaiDBOmHlDzXfLiLgrkgpP0&hl=zh­TW&sa=X&ved=0ahUKEwjb0M31vdLPAhUT9mMKHRJkDv4Q6AEIWDAH#v=onepage&q=wlc% 20heatbeat%20round%20trip%20time&f=false

Cisco Prime Infrastructure 3.1.3 Administrator Guide -Configuring High Availability [Cisco Prime Infrastructure] -Cisco http://www.cisco.com/c/en/us/td/docs/net_mgmt/prime/infrastructure/3-1-3/ administrator/guide/PIAdminBook/config_HA.html

Health Monitor (HM) detects failure conditions using the heartbeat messages that the two servers exchange. If the primary server is not responsive to three consecutive heartbeat messages from the secondary, it is considered to have failed.During the health check, HM also checks the application process status and database health; if there is no proper response to these checks, these are also treated as having failed.

The HA system takes approximately 10 to 15 seconds to detect a process failure on the primary server and initiate a failover. If the secondary server is unable to reach the primary server due to a network issue, it might take more time to initiate a failover. In addition, it may take additional time for the application processeson the secondary server to be fully operational.

High Availability FAQ -Cisco http://www.cisco.com/c/en/us/products/collateral/wireless/aironet-1130-ag­series/qa_c67-714540.html

Q.What are the recommendations for the network between the primary and secondary controllers connected via RP over Layer 2 VLAN/fiber to achieve client SSO? A.The Layer 2 network for RP connectivity needs to follow these recommendations to ensure appropriate performance in case of a switchover:

● Round-trip time (RTT) latency on the redundancy link: 80 ms or less for the default keep-alive timeout or 80percent of the configured keep-alive timeout

● Preferredmaximum transmission unit (MTU) on the redundancy link: 1500 or above

● Bandwidth on the redundancy link: 60 Mbps or more