[PATCH net-next v2] selftests: net: local_termination: test link-local protocols

[PATCH net-next v2] selftests: net: local_termination: test link-local protocols

[Daniel Golle]

Add tests to local_termination.sh to verify that link-local frames
arrive. On some switches the DSA driver uses bridges to connect the
user ports to their CPU ports. More "intelligent" switches typically
don't forward link-local frames, but may trap them to an internal
microcontroller. The driver may have to change trapping rules, so
link-local frames end up on the DSA CPU ports instead of being
silently dropped or trapped to the internal microcontroller of the
switch.

Add two tests which help to validate this has been done correctly:
 - Link-local STP BPDU should arrive at the Linux netdev when the
   bridge has STP disabled (BR_NO_STP), in which case the bridge
   forwards them rather than consuming them in the control plane
 - Link-local LLDP should arrive at standalone ports (and the test
   should be skipped on bridged ports similar to how it is done
   for the IEEE1588v2/PTP tests)

Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
v2: improve commit message (not "always"...)

 .../net/forwarding/local_termination.sh       | 25 +++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/tools/testing/selftests/net/forwarding/local_termination.sh b/tools/testing/selftests/net/forwarding/local_termination.sh
index 1f2bf6e818477..9bc9d25e71368 100755
--- a/tools/testing/selftests/net/forwarding/local_termination.sh
+++ b/tools/testing/selftests/net/forwarding/local_termination.sh
@@ -100,6 +100,15 @@ PTP_1588_IPV6_PDELAY_REQ=" \
 00 00 3e 37 63 ff fe cf 17 0e 00 01 00 01 05 7f \
 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 \
 00 00 00 00 00 00"
+LINK_LOCAL_STP_BPDU=" \
+01:80:c2:00:00:00 00:00:de:ad:be:ef 00 26 42 42 03 \
+00 00 00 00 00 80 00 aa bb cc dd ee ff 00 00 00 00 \
+80 00 aa bb cc dd ee ff 80 01 00 00 14 00 02 00 \
+0f 00"
+LINK_LOCAL_LLDP=" \
+01:80:c2:00:00:0e 00:00:de:ad:be:ef 88:cc 02 07 04 \
+00 11 22 33 44 55 04 05 05 65 74 68 30 06 02 00 \
+78 00 00"
 
 # Disable promisc to ensure we don't receive unknown MAC DA packets
 export TCPDUMP_EXTRA_FLAGS="-pl"
@@ -213,7 +222,15 @@ run_test()
 	mc_route_destroy $rcv_if_name
 	mc_route_destroy $send_if_name
 
+	ip maddress add 01:80:c2:00:00:00 dev $rcv_if_name
+	send_raw $send_if_name "$LINK_LOCAL_STP_BPDU"
+	ip maddress del 01:80:c2:00:00:00 dev $rcv_if_name
+
 	if [ $skip_ptp = false ]; then
+		ip maddress add 01:80:c2:00:00:0e dev $rcv_if_name
+		send_raw $send_if_name "$LINK_LOCAL_LLDP"
+		ip maddress del 01:80:c2:00:00:0e dev $rcv_if_name
+
 		ip maddress add 01:1b:19:00:00:00 dev $rcv_if_name
 		send_raw $send_if_name "$PTP_1588_L2_SYNC"
 		send_raw $send_if_name "$PTP_1588_L2_FOLLOW_UP"
@@ -304,7 +321,15 @@ run_test()
 		"$smac > $UNKNOWN_MACV6_MC_ADDR3, ethertype IPv6 (0x86dd)" \
 		true "$test_name"
 
+	check_rcv $rcv_if_name "Link-local STP BPDU" \
+		"> 01:80:c2:00:00:00" \
+		true "$test_name"
+
 	if [ $skip_ptp = false ]; then
+		check_rcv $rcv_if_name "Link-local LLDP" \
+			"> 01:80:c2:00:00:0e" \
+			true "$test_name"
+
 		check_rcv $rcv_if_name "1588v2 over L2 transport, Sync" \
 			"ethertype PTP (0x88f7).* PTPv2.* msg type *: sync msg" \
 			true "$test_name"
-- 
2.53.0

Re: [PATCH net-next v2] selftests: net: local_termination: test link-local protocols

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net-next.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 10 Mar 2026 18:10:32 +0000 you wrote:
> Add tests to local_termination.sh to verify that link-local frames
> arrive. On some switches the DSA driver uses bridges to connect the
> user ports to their CPU ports. More "intelligent" switches typically
> don't forward link-local frames, but may trap them to an internal
> microcontroller. The driver may have to change trapping rules, so
> link-local frames end up on the DSA CPU ports instead of being
> silently dropped or trapped to the internal microcontroller of the
> switch.
> 
> [...]

Here is the summary with links:
  - [net-next,v2] selftests: net: local_termination: test link-local protocols
    https://git.kernel.org/netdev/net-next/c/7e27d6202e90

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html