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[arp_update]: Flush neighbors with incorrect MAC info #17238

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merged 5 commits into from
Nov 30, 2023
Merged

[arp_update]: Flush neighbors with incorrect MAC info #17238

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70f9210
[arp_update]: Flush MAC mismatch neighbors
theasianpianist Nov 14, 2023
fba8776
[arp_update]: Use overloaded logger command
theasianpianist Nov 15, 2023
fd21923
[arp_update]: Flush neighs w/ stale MACs
theasianpianist Nov 15, 2023
42fb294
exclude ipv6 link local from MAC flush
theasianpianist Nov 20, 2023
5bc1b39
ping flushed neigh IPs
theasianpianist Nov 29, 2023
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39 changes: 34 additions & 5 deletions files/scripts/arp_update
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,11 @@

ARP_UPDATE_VARS_FILE="/usr/share/sonic/templates/arp_update_vars.j2"

# Overload `logger` command to include arp_update tag
logger () {
command logger -t "arp_update" "$@"
}

while /bin/true; do
# find L3 interfaces which are UP, send ipv6 multicast pings
ARP_UPDATE_VARS=$(sonic-cfggen -d -t ${ARP_UPDATE_VARS_FILE})
Expand All @@ -19,7 +24,7 @@ while /bin/true; do
STATIC_ROUTE_IFNAMES=($(echo $ARP_UPDATE_VARS | jq -r '.static_route_ifnames'))
# on supervisor/rp exit the script gracefully
if [[ -z "$STATIC_ROUTE_NEXTHOPS" ]] || [[ -z "$STATIC_ROUTE_IFNAMES" ]]; then
logger "arp_update: exiting as no static route in packet based chassis"
logger "exiting as no static route in packet based chassis"
exit 0
fi
for i in ${!STATIC_ROUTE_NEXTHOPS[@]}; do
Expand All @@ -38,7 +43,7 @@ while /bin/true; do
interface="${STATIC_ROUTE_IFNAMES[i]}"
if [[ -z "$interface" ]]; then
# should never be here, handling just in case
logger "ERR: arp_update: missing interface entry for static route $nexthop"
logger -p error "missing interface entry for static route $nexthop"
continue
fi
intf_up=$(ip link show $interface | grep "state UP")
Expand All @@ -47,7 +52,7 @@ while /bin/true; do
eval $pingcmd
# STALE entries may appear more often, not logging to prevent periodic syslogs
if [[ -z $(echo ${neigh_state} | grep 'STALE') ]]; then
logger "arp_update: static route nexthop not resolved ($neigh_state), pinging $nexthop on $interface"
logger "static route nexthop not resolved ($neigh_state), pinging $nexthop on $interface"
fi
fi
fi
Expand All @@ -70,6 +75,30 @@ while /bin/true; do
fi
done

# find neighbor entries with aged MAC and flush/relearn them
STALE_NEIGHS=$(ip neigh show | grep -v "fe80" | grep "STALE" | awk '{print $1 "," $5}' | tr [:lower:] [:upper:])
for neigh in $STALE_NEIGHS; do
ip="$( cut -d ',' -f 1 <<< "$neigh" )"
mac="$( cut -d ',' -f 2 <<< "$neigh" )"
if [[ -z $(sonic-db-cli ASIC_DB keys "ASIC_STATE:SAI_OBJECT_TYPE_FDB_ENTRY*${mac}*") ]]; then
timeout 0.2 ping -c1 -w1 $ip > /dev/null
fi
done

# Flush neighbor entries with MAC mismatch between kernel and APPL_DB
KERNEL_NEIGH=$(ip neigh show | grep -v "fe80" | grep -v "FAILED\|INCOMPLETE" | cut -d ' ' -f 1,3,5 --output-delimiter=',' | tr -d ' ')
for neigh in $KERNEL_NEIGH; do
ip="$( cut -d ',' -f 1 <<< "$neigh" )"
intf="$( cut -d ',' -f 2 <<< "$neigh" )"
kernel_mac="$( cut -d ',' -f 3 <<< "$neigh" )"
appl_db_mac="$(sonic-db-cli APPL_DB hget NEIGH_TABLE:$intf:$ip neigh)"
if [[ $kernel_mac != $appl_db_mac ]]; then
logger -p warning "MAC mismatch for ${ip} on ${intf} - kernel: ${kernel_mac}, APPL_DB: ${appl_db_mac}"
ip neigh flush $ip
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timeout 0.2 ping -c1 -w1 $ip > /dev/null
fi
done

VLAN=$(echo $ARP_UPDATE_VARS | jq -r '.vlan')
SUBTYPE=$(sonic-db-cli CONFIG_DB hget 'DEVICE_METADATA|localhost' 'subtype' | tr '[:upper:]' '[:lower:]')
for vlan in $VLAN; do
Expand Down Expand Up @@ -158,11 +187,11 @@ while /bin/true; do
if [[ $ip == *"."* ]] && [[ ! $KERNEIGH4 =~ "${ip},${intf}" ]]; then
pingcmd="timeout 0.2 ping -I $intf -n -q -i 0 -c 1 -W 1 $ip >/dev/null"
eval $pingcmd
logger "arp_update: mismatch arp entry, pinging ${ip} on ${intf}"
logger "mismatch arp entry, pinging ${ip} on ${intf}"
elif [[ $ip == *":"* ]] && [[ ! $KERNEIGH6 =~ "${ip},${intf}" ]]; then
ping6cmd="timeout 0.2 ping6 -I $intf -n -q -i 0 -c 1 -W 1 $ip >/dev/null"
eval $ping6cmd
logger "arp_update: mismatch v6 nbr entry, pinging ${ip} on ${intf}"
logger "mismatch v6 nbr entry, pinging ${ip} on ${intf}"
fi
fi
done
Expand Down
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