VPLS Tunnel not working - L2MTU on bridge wrong

RouterOS Forwarding Protocols
1

Hi gurus,

I had a wireless bridge that is working fine. I wanted to add a 2nd station, so I changed to AP-Bridge
and copied the settings on the station to a new one (with the appropriate IPs changed).

R0 (AP-BRIDGE)
VPLS1: ip=172.16.0.1
ETHER1: ip=192.168.0.18
WLAN1: ssid=“wrcbridge”
BRIDGE: ports=ETHER1, VPLS1

R1 (station)
VPLS1: ip=172.16.0.2
ETHER1: ip=192.168.0.17
WLAN1: ssid=“wrcbridge”
BRIDGE: ports=ETHER1, VPLS1

R2 (station)
VPLS1: ip=172.16.0.3
ETHER1: ip=192.168.0.19
WLAN1: ssid=“wrcbridge”
BRIDGE: ports=ETHER1, VPLS1

Current state:

  • Original bridge works fine (R0<->R1)
  • New bridge (R0<->R2) - I can ping the VPLS address from the AP-Bridge, but I cannot ping the static IP on the Ethernet interface.

In reading some other posts, I see mention to ensure that the bridge l2mtu is less than wlan/vpls l2mtus.

In looking at my working station (R1), I see:

[admin@MikroTik] > /interface print 
Flags: D - dynamic, X - disabled, R - running, S - slave 
 #     NAME                                                                    TYPE             MTU   L2MTU
 0  R  ether1                                                                  ether            1500  1526 
 1  R  bridge1                                                                 bridge           1500  1500 
 2  R  wlan1                                                                   wlan             1500  2290 
 3  X  wlan2                                                                   wlan             1500 
 4  R  vpls1                                                                   vpls             1500  1500

In looking at the non-working station (R2), I see:

[admin@MikroTik] > /interface print
Flags: D - dynamic, X - disabled, R - running, S - slave 
 #     NAME                                                              TYPE               MTU L2MTU  MAX-L2MTU
 0  R  ether1                                                            ether             1500  1526       1526
 1  R  wlan1                                                             wlan              1500  2290
 2  X  wlan2                                                             wlan              1500
 3  R  bridge1                                                           bridge            1500  1526
 4     vpls1                                                             vpls              1500  1500

I see 2 issues:

  • Bridge1 L2MTU is 1526. I believe I need that to be 1500.
  • VPLS1 is not running

How do I reset the l2mtu on Bridge1 on R2 ? I assume that’s why VPLS1 is not happy.

Thanks for any pointers !

Ward

2

The bridge interface inherits the lowest supported MTU so 1500 is right.
Also if you have the ethernet interface that mpls/VPLS is running on in a bridge I don’t think this works.

Looks like you have 3 devices all trying to be a part of the same VPLS tunnel?
I’ve never tried having a VPLS tunnel with 3 end points ? Didn’t think it was possible

3

Thanks Inssomniak for the pointer !

Solution: I added a 2nd VPLS for R0<->R2, added it to the bridge on R0 and everything is behaving appropriately.