[OpenWrt-Devel] [PATCHv2] Allow VLAN filtering if needed.

[Jonathan Thibault]

Greetings,

I would like to propose enabling CONFIG_BRIDGE_VLAN_FILTERING on OpenWRT 
releases.

This allows us to use the bridge as a managed switch and gracefully 
handle mixed tagged and untagged frames. Prior to this, the only 
alternative was creating one bridge per vlan which quickly becomes a 
nightmare and still won't let you mix both tagged and untagged frames on 
the physical port without some complex ebtables magic.

This is in line with the notion that OpenWRT is the network go-to swiss 
army knife when you need a nice set-and-forget, low maintenance box to 
handle a specific task.

Current builds of the ip-bridge package already fully support this 
feature so the only requirement is enabling the kernel config.

This is disabled by default so existing bridge configurations will not 
be affected.  This patch only gives the ability to turn it on with an 
'ip link' command.  If there is interest, I could look into making the 
feature accessible via uci configuration.

It causes about 3.1% hit on raw bridging speed, which is relatively 
trivial considering that I had to use 300 byte packets to strain the CPU 
enough to notice a slowdown at all.  The ER8 would chug along at wire 
speed otherwise, and that's using only one core.  Since the typical 
bridge use case on OpenWRT is wireless, I doubt it would be noticeable 
at all.

With BRIDGE_VLAN_FILTERING

iperf -u -c 192.168.1.105 -b 1G -l 300
------------------------------------------------------------
Client connecting to 192.168.1.105, UDP port 5001
Sending 300 byte datagrams, IPG target: 2.24 us (kalman adjust)
UDP buffer size:  208 KByte (default)
------------------------------------------------------------
[  3] local 192.168.1.12 port 58045 connected with 192.168.1.105 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   977 MBytes   820 Mbits/sec
[  3] Sent 3414986 datagrams
[  3] Server Report:
[  3]  0.0-10.0 sec   811 MBytes   680 Mbits/sec   0.000 ms 
581210/3414986 (0%)

Without BRIDGE_VLAN_FILTERING

iperf -u -c 192.168.1.105 -b 1G -l 300
------------------------------------------------------------
Client connecting to 192.168.1.105, UDP port 5001
Sending 300 byte datagrams, IPG target: 2.24 us (kalman adjust)
UDP buffer size:  208 KByte (default)
------------------------------------------------------------
[  3] local 192.168.1.12 port 36645 connected with 192.168.1.105 port 5001
[ ID] Interval       Transfer     Bandwidth
[  3]  0.0-10.0 sec   977 MBytes   820 Mbits/sec
[  3] Sent 3414990 datagrams
[  3] Server Report:
[  3]  0.0-10.0 sec   836 MBytes   701 Mbits/sec   0.000 ms 
493950/3414990 (0%)

In terms of kernel size, it uses 16KB (6753K vs 6737K on ER8) so a 
0.002% hit.  The exact 16KB is probably just due to how the kernel is 
compressed.

---

v2: Enable the right CONFIG_ on 4.14.  Thanks Felix for pointing out my 
silliness :)

diff --git a/target/linux/generic/config-4.14 
b/target/linux/generic/config-4.14
index 97207cf2eb..7d4750f461 100644
--- a/target/linux/generic/config-4.14
+++ b/target/linux/generic/config-4.14
@@ -627,7 +627,7 @@ CONFIG_BRIDGE=y
  CONFIG_BRIDGE_IGMP_SNOOPING=y
  # CONFIG_BRIDGE_NETFILTER is not set
  # CONFIG_BRIDGE_NF_EBTABLES is not set
-# CONFIG_BRIDGE_VLAN_FILTERING is not set
+CONFIG_BRIDGE_VLAN_FILTERING=y
  # CONFIG_BROADCOM_PHY is not set
  CONFIG_BROKEN_ON_SMP=y
  # CONFIG_BSD_DISKLABEL is not set
diff --git a/target/linux/generic/config-4.9 
b/target/linux/generic/config-4.9
index 979028f04a..860b39b428 100644
--- a/target/linux/generic/config-4.9
+++ b/target/linux/generic/config-4.9
@@ -598,7 +598,7 @@ CONFIG_BRIDGE=y
  CONFIG_BRIDGE_IGMP_SNOOPING=y
  # CONFIG_BRIDGE_NETFILTER is not set
  # CONFIG_BRIDGE_NF_EBTABLES is not set
-# CONFIG_BRIDGE_VLAN_FILTERING is not set
+CONFIG_BRIDGE_VLAN_FILTERING=y
  # CONFIG_BROADCOM_PHY is not set
  CONFIG_BROKEN_ON_SMP=y
  # CONFIG_BSD_DISKLABEL is not set


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