Records in arp table are staying active

[hulvat]

Hello,
in Arp table on server are staying records, after device(-s) is/are disconnect from network namely several minutes/hours/.../etc.
kernel config:

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net.ipv4.neigh.default.mcast_solicit = 3
net.ipv4.neigh.default.ucast_solicit = 3
net.ipv4.neigh.default.app_solicit = 0
net.ipv4.neigh.default.retrans_time = 99
net.ipv4.neigh.default.base_reachable_time = 30
net.ipv4.neigh.default.delay_first_probe_time = 5
net.ipv4.neigh.default.gc_stale_time = 60
net.ipv4.neigh.default.unres_qlen = 3
net.ipv4.neigh.default.proxy_qlen = 64
net.ipv4.neigh.default.anycast_delay = 99
net.ipv4.neigh.default.proxy_delay = 79
net.ipv4.neigh.default.locktime = 99
net.ipv4.neigh.default.retrans_time_ms = 1000
net.ipv4.neigh.default.base_reachable_time_ms = 30000
net.ipv4.neigh.default.gc_interval = 30
net.ipv4.neigh.default.gc_thresh1 = 128
net.ipv4.neigh.default.gc_thresh2 = 512
net.ipv4.neigh.default.gc_thresh3 = 1024
net.ipv4.neigh.lo.mcast_solicit = 3
net.ipv4.neigh.lo.ucast_solicit = 3
net.ipv4.neigh.lo.app_solicit = 0
net.ipv4.neigh.lo.retrans_time = 99
net.ipv4.neigh.lo.base_reachable_time = 30
net.ipv4.neigh.lo.delay_first_probe_time = 5
net.ipv4.neigh.lo.gc_stale_time = 60
net.ipv4.neigh.lo.unres_qlen = 3
net.ipv4.neigh.lo.proxy_qlen = 64
net.ipv4.neigh.lo.anycast_delay = 99
net.ipv4.neigh.lo.proxy_delay = 79
net.ipv4.neigh.lo.locktime = 99
net.ipv4.neigh.lo.retrans_time_ms = 1000
net.ipv4.neigh.lo.base_reachable_time_ms = 30000
net.ipv4.neigh.eth0.mcast_solicit = 3
net.ipv4.neigh.eth0.ucast_solicit = 3
net.ipv4.neigh.eth0.app_solicit = 0
net.ipv4.neigh.eth0.retrans_time = 99
net.ipv4.neigh.eth0.base_reachable_time = 30
net.ipv4.neigh.eth0.delay_first_probe_time = 5
net.ipv4.neigh.eth0.gc_stale_time = 60
net.ipv4.neigh.eth0.unres_qlen = 3
net.ipv4.neigh.eth0.proxy_qlen = 64
net.ipv4.neigh.eth0.anycast_delay = 99
net.ipv4.neigh.eth0.proxy_delay = 79
net.ipv4.neigh.eth0.locktime = 99
net.ipv4.neigh.eth0.retrans_time_ms = 1000
net.ipv4.neigh.eth0.base_reachable_time_ms = 30000
net.ipv4.neigh.tap0.mcast_solicit = 3
net.ipv4.neigh.tap0.ucast_solicit = 3
net.ipv4.neigh.tap0.app_solicit = 0
net.ipv4.neigh.tap0.retrans_time = 99
net.ipv4.neigh.tap0.base_reachable_time = 30
net.ipv4.neigh.tap0.delay_first_probe_time = 5
net.ipv4.neigh.tap0.gc_stale_time = 60
net.ipv4.neigh.tap0.unres_qlen = 3
net.ipv4.neigh.tap0.proxy_qlen = 64
net.ipv4.neigh.tap0.anycast_delay = 99
net.ipv4.neigh.tap0.proxy_delay = 79
net.ipv4.neigh.tap0.locktime = 99
net.ipv4.neigh.tap0.retrans_time_ms = 1000
net.ipv4.neigh.tap0.base_reachable_time_ms = 30000

ip -s ne list

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192.168.0.146 dev eth0 lladdr cc:ff:d0:f1:0c:XX used 358379/358379/166033 STALE
192.168.0.127 dev eth0 lladdr a0:9d:35:b3:98:XX used 160018/160713/160018 STALE

Centos 6.7 kernel 2.6.32-573.7.1.el6.x86_64

Why? Any idea?

[b0n40]

Hi,

try

# Tell the gc when to become aggressive with arp table cleaning.
# Adjust this based on size of the LAN. 1024 is suitable for most /24 networks
net.ipv4.neigh.default.gc_thresh2 = 1024

# Adjust where the gc will leave arp table alone - set to 32.
net.ipv4.neigh.default.gc_thresh1 = 32

# Adjust to arp table gc to clean-up more often
net.ipv4.neigh.default.gc_interval = 30

net.ipv4.neigh.default.gc_stale_time - ?

https://klaver.it/linux/sysctl.conf

Good luck !