Requirement:
WAN health-check already provides the means of checking reachability and latency to HQ datacenter through each of the WAN links using ICMP ping.
Starting Aruba OS 6.5, WAN health-check phase 2 will help us check reach ability by using the below features-
UDP ping,
Measuring latency,
Packet loss,
Jitter,
Bandwidth utilization.
Solution:
HCM is the module responsible for handling WAN health checks.
Pre 6.5
The Health check manager (HCM) module periodically checks for reach ability to Master controller from each of the uplink WAN interfaces. It also measures the round trip latency to the Master controller using ICMP ping probes.
Starting 6.5
This is now enhanced to use UDP protocol for the reachability and latency to Master.
The UDP port 4500 will be most likely opened up in the DMZ firewall and using the same port will allow the packets to pass through the firewall without any configuration change on the firewall.
The UDP packets are also used in measuring the jitter on the WAN links.
WORKFLOW
Health Check Manager will receive the IP probe and jitter configuration from FPAPPS.
If IP probe mode is configured as “UDP”, HCM will periodically probe the link’s reachability and latency by initiating UDP/RTP packets.
If “jitter” is configured under IP probe profile, then HCM will not initiate the RTP packets and instead sends a jitter initiate message and start the jitter test on its behalf.
HCM will measure the active latency and jitter from the timestamp in the UDP/RTP packets, and computes the link’s Bandwidth utilization from the Tunnel traffic statistics.
HCM also computes Health score for each link based on latency, jitter and packet loss. HCM will share the link metrics with the modules that has registered for the information.
The modules that would register for the metrics are Load balance module in FPAPPS, Bandwidth management module in AUTH and the WebUI module.
HCM will report this information to FPAPPS every 10 seconds.
Configuration:
WebUI
Navigate to Configuration --> Smart Config--> WAN
COMMAND LINE
Verification# show ip probe - This command shows IP probe profile parameters.
# show ip health-check - This command will display health-check status and details through each of the uplink interfaces.
# show ip health-check <probe_ip> - This command will display the detailed delay, jitter and packet loss measurements for an uplink.
# show jitter <probe_ip> <src_intf> - This command will display the results of the test action command.
# show datapath wan-hc counters - This command will display datapath statistics for the UDP reach ability check