Different delay between MPLS and VPLS

RouterOS Forwarding Protocols
1

Hi

I’m trying to understand why this VPLS tunnel has a bigger delay than MPLS forwarding and plain routing.

VPLS tunnel

172.16.249.57                              56  64 10ms 
    sent=100 received=99 packet-loss=1% min-rtt=8ms avg-rtt=18ms max-rtt=68ms
> /tool traceroute 172.16.249.57
 # ADDRESS                                 RT1   RT2   RT3   STATUS
 1 172.16.249.57                           16ms  10ms  25ms

MPLS forwarding

172.16.240.2                               56  60 10ms 
    sent=100 received=100 packet-loss=0% min-rtt=7ms avg-rtt=13ms max-rtt=34ms 
> /tool traceroute 172.16.240.2
 # ADDRESS                                 RT1   RT2   RT3   STATUS
 1 172.16.6.225                            17ms  37ms  9ms   <MPLS:L=22,E=0>
 2 172.16.6.226                            12ms  14ms  11ms  <MPLS:L=22,E=0>
 3 172.16.8.254                            9ms   10ms  14ms  <MPLS:L=2257,E=0>
 4 172.16.8.234                            18ms  15ms  10ms  <MPLS:L=214,E=0>
 5 172.16.8.249                            10ms  12ms  17ms  <MPLS:L=3872,E=0>
 6 172.16.240.2                            10ms  11ms  13ms

“Simple” forwarding

172.16.253.10                              56  60 9ms  
    sent=100 received=100 packet-loss=0% min-rtt=7ms avg-rtt=13ms max-rtt=48ms 
> /tool traceroute 172.16.253.10
 # ADDRESS                                 RT1   RT2   RT3   STATUS
 1 172.16.6.226                            1ms   1ms   1ms
 2 172.16.8.254                            20ms  4ms   12ms
 3 172.16.8.234                            5ms   32ms  6ms
 4 172.16.8.249                            9ms   6ms   8ms
 5 172.16.253.10                           10ms  11ms  10ms

Link between 172.16.8.254-172.16.6.226 and 172.16.8.234-172.16.8.249 are wireless link, 802.11N with Nv2.

What could I check?

Thank you

2

This is very normal and will be observed in Cisco MPLS networks as well. The extra delay you are seeing is due to the encapsulation/decapsulation of a Layer 2 header inside of an MPLS packet.

More overhead = slightly more delay

3

Yes, you’re right. But on wireless link under heavy load, I see routed ping are faster than VPLS tunnelled; also less ping are lost.
So I suspect there’s some kind of QoS that I’m not aware.

4

The QoS I wasn’t aware is Nv2 QoS policy.
Changed priority for packets going over VPLS interfaces and delay desappeared.