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    :Do I need to make additional configurations for ECS instances on classic networks used as backend servers for SLB?

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    :Do I need to make additional configurations for ECS instances on classic networks used as backend servers for SLB?

    Last Updated:Apr 25, 2025

    Note

    This topic applies to Elastic Compute Service (ECS) instances on classic networks. No additional configuration is required for ECS instances in Virtual Private Clouds (VPCs).

    In most cases, no additional configuration is required for ECS instances used as backend servers for an Server Load Balancer (SLB) instance. However, if you cannot access Linux ECS instances associated with Layer 4 SLB instances (using the TCP protocol), ensure that the following three parameters in the Linux system configuration file /etc/sysctl.conf are set to 0.

    net.ipv4.conf.default.rp_filter = 0

net.ipv4.conf.all.rp_filter = 0

net.ipv4.conf.eth0.rp_filter = 0

    If ECS instances deployed within the same internal CIDR block need to communicate with each other but failed, check whether the following parameters are configured as follows:

    net.ipv4.conf.default.arp_announce =2

net.ipv4.conf.all.arp_announce =2

    After modifying the parameters, run the sysctl -p command to apply the modification.