What Are the Precautions of Using UDP?

Ravger · Created May 4, 2017 05:53:47

In the health check of a load balancer, the UDP and Ping packets are used to obtain the status of the backend ECS. You must ensure that Internet Control Message Protocol (ICMP) is enabled on the backend ECS.
Log in to the backend ECS and run the following command as user root:
cat /proc/sys/net/ipv4/icmp_echo_ignore_all
If the returned value is 1, ICMP is disabled. If the returned value is 0, ICMP is enabled.
If UDP is used, the health check result may be different from the actual status of ELB.
If the backend ECS runs Linux, the sending rate of ICMP packets on the ECS will be restricted due to the anti-ICMP attack protection mechanism. In this case, even when a service exception has occurred, ELB does not receive the error message "port XX unreachable" and still determines that the health check is successful. This results in an inconsistency between the health check result and the actual ELB status.
A listener using UDP is not allowed for a private network load balancer.

jino94 · Created May 25, 2018 04:19:10

sze_van · Created Jun 13, 2018 01:39:21

:)