sonic-buildimage/files/scripts/arp_update
Lawrence Lee 572af1dcdf
[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
2023-11-30 14:23:05 -08:00

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#!/bin/bash
#
# usage:
# arp_update:
# Send ipv6 multicast pings to all "UP" L3 interfaces including vlan interfaces to
# refresh link-local addresses from neighbors.
# Send gratuitous ARP/NDP requests to VLAN member neighbors to refresh
# the ipv4/ipv6 neighbors state.
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 ${ARP_UPDATE_VARS_FILE})
SWITCH_TYPE=$(echo $ARP_UPDATE_VARS | jq -r '.switch_type')
if [[ "$SWITCH_TYPE" == "chassis-packet" ]]; then
# Get array of Nexthops and ifnames. Nexthops and ifnames are mapped one to one
STATIC_ROUTE_NEXTHOPS=($(echo $ARP_UPDATE_VARS | jq -r '.static_route_nexthops'))
STATIC_ROUTE_IFNAMES=($(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 "exiting as no static route in packet based chassis"
exit 0
fi
for i in ${!STATIC_ROUTE_NEXTHOPS[@]}; do
nexthop="${STATIC_ROUTE_NEXTHOPS[i]}"
if [[ $nexthop == *"."* ]]; then
neigh_state=$(ip -4 neigh show | grep -w $nexthop | tr -s ' ')
ping_prefix=ping
elif [[ $nexthop == *":"* ]] ; then
neigh_state=$(ip -6 neigh show | grep -w $nexthop | tr -s ' ')
ping_prefix=ping6
fi
# Check if there is an INCOMPLETE, FAILED, or STALE entry and try to resolve it again.
# STALE entries may be present if there is no traffic on a path. A far-end down event may not
# clear the STALE entry. Refresh the STALE entry to clear the table.
if [[ -z "${neigh_state}" ]] || [[ -n $(echo ${neigh_state} | grep 'INCOMPLETE\|FAILED\|STALE') ]]; then
interface="${STATIC_ROUTE_IFNAMES[i]}"
if [[ -z "$interface" ]]; then
# should never be here, handling just in case
logger -p error "missing interface entry for static route $nexthop"
continue
fi
intf_up=$(ip link show $interface | grep "state UP")
if [[ -n "$intf_up" ]]; then
pingcmd="timeout 0.2 $ping_prefix -I ${interface} -n -q -i 0 -c 1 -W 1 $nexthop >/dev/null"
eval $pingcmd
# STALE entries may appear more often, not logging to prevent periodic syslogs
if [[ -z $(echo ${neigh_state} | grep 'STALE') ]]; then
logger "static route nexthop not resolved ($neigh_state), pinging $nexthop on $interface"
fi
fi
fi
done
sleep 150
continue
fi
# find L3 interfaces which are UP, send ipv6 multicast pings
INTERFACE=$(echo $ARP_UPDATE_VARS | jq -r '.interface')
PC_INTERFACE=$(echo $ARP_UPDATE_VARS | jq -r '.pc_interface')
VLAN_SUB_INTERFACE=$(echo $ARP_UPDATE_VARS | jq -r '.vlan_sub_interface')
ALL_INTERFACE="$INTERFACE $PC_INTERFACE $VLAN_SUB_INTERFACE"
for intf in $ALL_INTERFACE; do
ping6cmd="ping6 -I $intf -n -q -i 0 -c 1 -W 0 ff02::1 >/dev/null"
intf_up=$(ip link show $intf | grep "state UP")
if [[ -n "$intf_up" ]]; then
eval $ping6cmd
fi
done
# find neighbor entries with aged MAC and flush/relearn them
STALE_NEIGHS=$(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 $VLAN; do
# generate a list of arping commands:
# arping -q -w 0 -c 1 -i <VLAN interface> <IP 1>;
# arping -q -w 0 -c 1 -i <VLAN interface> <IP 2>;
# ...
arpingcmd="sed -e 's/ / -i /' -e 's/^/arping -q -w 0 -c 1 /' -e 's/$/;/'"
ipcmd="ip -4 neigh show | grep $vlan | cut -d ' ' -f 1,3 | $arpingcmd"
eval `eval $ipcmd`
# send ipv6 multicast pings to Vlan interfaces to get/refresh link-local addrs
ping6cmd="timeout 1 ping6 -I $vlan -n -q -i 0 -c 1 -W 0 ff02::1 >/dev/null"
eval $ping6cmd
# generate a list of ndisc6 commands (exclude link-local addrs since it is done above):
# ndisc6 -q -w 0 -1 <IP 1> <VLAN interface>;
# ndisc6 -q -w 0 -1 <IP 2> <VLAN interface>;
# ...
ndisc6cmd="sed -e 's/^/ndisc6 -q -w 0 -1 /' -e 's/$/;/'"
ip6cmd="ip -6 neigh show | grep -v fe80 | grep $vlan | cut -d ' ' -f 1,3 | $ndisc6cmd"
eval `eval $ip6cmd`
if [[ $SUBTYPE == "dualtor" ]]; then
# capture all current failed/incomplete IPv6 neighbors in the kernel to avoid situations where new neighbors are learned
# in the middle of the below sequence of commands
unresolved_kernel_neighbors=$(ip -6 neigh show | grep -v fe80 | grep $vlan | grep -E 'FAILED|INCOMPLETE')
failed_kernel_neighbors=$(echo "$unresolved_kernel_neighbors" | grep FAILED | cut -d ' ' -f 1)
# it's possible for kernel neighbors to fall out of sync with the hardware
# this can result in failed neighbors entries that don't have corresponding zero MAC neighbor entries
# and therefore don't have tunnel routes installed in the hardware
# flush these neighbors from the kernel to force relearning and resync them to the hardware:
# 1. for every FAILED or INCOMPLETE neighbor in the kernel, check if there is a corresponding zero MAC neighbor in APPL_DB
# 2. if no zero MAC neighbor entry exists, flush the kernel neighbor entry
# - generates the command 'ip neigh flush <neighbor IPv6>' for all such neighbors
unsync_neighbors=$(echo "$unresolved_kernel_neighbors" | cut -d ' ' -f 1 | xargs -I{} bash -c "if [[ -z \"\$(sonic-db-cli APPL_DB hget NEIGH_TABLE:$vlan:{} neigh)\" ]]; then echo '{}'; fi")
if [[ ! -z "$unsync_neighbors" ]]; then
ip_neigh_flush_cmd="echo \"$unsync_neighbors\" | sed -e 's/^/ip neigh flush /' -e 's/$/;/'"
eval `eval "$ip_neigh_flush_cmd"`
sleep 2
fi
# generates the following command for each FAILED or INCOMPLETE IPv6 neighbor
# timeout 0.2 ping <neighbor IPv6> -n -q -i 0 -c 1 -W 1 -I <VLAN name> >/dev/null
if [[ ! -z "$unresolved_kernel_neighbors" ]]; then
ping6_template="sed -e 's/^/timeout 0.2 ping /' -e 's/,/ -n -q -i 0 -c 1 -W 1 -I /' -e 's/$/ >\/dev\/null;/'"
failed_ip6_neigh_cmd="echo \"$unresolved_kernel_neighbors\" | cut -d ' ' -f 1,3 --output-delimiter=',' | $ping6_template"
eval `eval "$failed_ip6_neigh_cmd"`
# allow some time for any transient INCOMPLETE neighbors to transition to FAILED
sleep 5
fi
# manually set any remaining FAILED entries to permanently INCOMPLETE
# once these entries are INCOMPLETE, any subsequent neighbor advertisement messages are able to resolve the entry
# ignore INCOMPLETE neighbors since if they are transiently incomplete (i.e. new kernel neighbors that we are attempting to resolve for the first time),
# setting them to permanently incomplete here means the kernel will never generate a netlink message for that neighbor
# generates the following command for each FAILED IPv6 neighbor
# ip neigh replace <neighbor IPv6> dev <VLAN name> nud incomplete
failed_kernel_neighbors=$(ip -6 neigh show | grep -v fe80 | grep $vlan | grep -E 'FAILED')
if [[ ! -z "$failed_kernel_neighbors" ]]; then
neigh_replace_template="sed -e 's/^/ip neigh replace /' -e 's/,/ dev /' -e 's/$/ nud incomplete;/'"
ip_neigh_replace_cmd="echo \"$failed_kernel_neighbors\" | cut -d ' ' -f 1,3 --output-delimiter=',' | $neigh_replace_template"
eval `eval "$ip_neigh_replace_cmd"`
fi
fi
done
# sleep here before handling the mismatch as it is not required during startup
sleep 300
# refresh neighbor entries from APP_DB in case of mismatch with kernel
DBNEIGH=$(sonic-db-cli APPL_DB keys NEIGH_TABLE*)
# resolve neighbor entries from CONFIG_DB in case of mismatch with kernel
DBNEIGH="$DBNEIGH $(sonic-db-cli CONFIG_DB keys NEIGH* | sed -e 's/|/:/g')"
KERNEIGH4=$(ip -4 neigh show | grep Vlan | grep -v 'FAILED\|INCOMPLETE' | cut -d ' ' -f 1,3 --output-delimiter=',')
KERNEIGH6=$(ip -6 neigh show | grep -v fe80 | grep Vlan | grep -v 'FAILED\|INCOMPLETE' | cut -d ' ' -f 1,3 --output-delimiter=',')
for neigh in $DBNEIGH; do
intf="$( cut -d ':' -f 2 <<< "$neigh" )"
ip="$( cut -d ':' -f 3- <<< "$neigh" )"
if [[ $intf == *"Vlan"* ]]; then
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 "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 "mismatch v6 nbr entry, pinging ${ip} on ${intf}"
fi
fi
done
done