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

 [arp_update]: Flush MAC mismatch neighbors

- Check for MAC mismatch between neighbor entries in the kernel and APPL_DB
- Flush any entries with a mismatch

files/scripts/arp_update

@@ -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 ${ARP_UPDATE_VARS_FILE})
@@ -19,7 +24,7 @@ while /bin/true; do
  STATIC_ROUTE_IFNAMES=($(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 ${!STATIC_ROUTE_NEXTHOPS[@]}; do
@@ -38,7 +43,7 @@ while /bin/true; do
  interface="${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")
@@ -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
@@ -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
+ 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
@@ -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