Understanding MPLS with a switch in between

Hello Members,
Please help me understand if this would be a correct scenario to run MPLS.

Mikrotik > Switch > Mikrotik

Would the switch create any problem for the packet flow if I am running MPLS to connect two nodes?

Thank you.


Sent from my SAMSUNG-SM-G935A using Tapatalk
Screenshot_20170523-143607.png

It depends on the switch.

A decent switch will be “transparent” to MPLS.

A “el cheapo” one (software based, like most included on ISP routers, or *-link brands) won’t be so transparent and you can expect funkyness…

Give me an example of a decent switch please.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Mikrotik CRS line is not expensive at all. Additionally you will be able to manage them using Winbox as any other routerboard.

Do you already have switches around? Which brands/models?

Of course, any routerboard with switch chip will do also.

I am using Mikrotik for the routers but as I will be having only 1 P2P which will be carrying main BW and user data.

So if I would use Mikrotik > switch > mikrotik

MPLS running on both Mikrotik would the switch cause any congestion?

Sent from my SAMSUNG-SM-G935A using Tapatalk

Switch chip can pass traffic at wire speed, so as long as you pick the switch with desired wire speed there will be no congestion.

You also want to make sure the switch in between supports at least a 1530 byte frame size to be able to leverage all the features of MPLS like VPLS. Most switches do, but there are still some out there that don’t

This helps thank you.

Sent from my SAMSUNG-SM-G935A using Tapatalk

Installed a mikrotik CSS but the moment I connect MPLS/VPLS goes down. What am I missing??

Installed mikrotik CSS326 but MPLS/VPLS goes down.. what am I missing?

If it goes down with a switch in between either: a) the switch is limiting the MTU below what you need for VPLS, or b) there is another issue unrelated to the switch and the tunnel would go down even without the switch

The tunnel works fine on my other cisco switch. But the moment I connect to CSS326 VPLS goes down.

I upgraded the firmware to 2.4 also tried enabling vpls on the ports I am using.. However it still goes down.

Something is probably wrong with your config

The switch config? I haven’t done any config apart from enabling VPLS on each port.

You can’t “enable VPLS” on each port of a switch.

I’m actually not clear on what you are trying to do, either you are:

a) trying to incorporate your switch between two MPLS LDP routers so that it can provide routing for tunnels on the back end, of which some could be VPLS (but then you would need no ‘VPLS’ configuration on such a switch)

or

b) terminating a VPLS tunnel on router A and terminating another VPLS tunnel on router B, and interconnecting the layer2 domains with a switch in between going from one VPLS tunnel to another one for purposes unknown, and both of these tunnels terminate somewhere else that you aren’t showing us for reasons unknown.

Your original diagram which said ‘MPLS ↔ switch <—> MPLS’ in picture form was essentially useless in understanding what you want or the way you are trying to set things up.

Do this simple test:

  1. test with network cable connecting the two routers directly to each other - does it work?
  2. plug in MikroTik switch with default config (no firewall) in between, does it work?

Basically 2 should yield the same results as 1. If it doesn’t, either your switch is faulty (unlikely) or more likely your routers are configured wrong and there is nothing wrong with the switch.

Since you seem to think there is a way to “enable VPLS” on the port of a switch (and there is no such thing) I am guessing you most likely don’t really fully understand MPLS/VPLS, and you are setting it up wrong and blaming the switch for your misconfiguration. This is of course fine b/c not everybody understands this stuff at the beginning, but more information is required.

It is like someone coming and saying “I have two routers. They work. When I connect a switch between the routers, they stop working. What is wrong?”

There is no information, no detail, if you want someone to help you need to provide enough information to make it understandable what you are trying to accomplish.

Option a.

Incorporating a switch between teo MPLS LDP routers. At first I only connected the CSS326 right from the box. MPLS did not work. Then upgraded the firmware still did not work.

Next I enabled VPLS on one port of the switch it worked. After a few minutes it went down.

If the port had no VPLS enabled it won’t just connect. Is there any setting on the switch that needs to be done for it to allow larger packets?

Sent from my SAMSUNG-SM-G935A using Tapatalk

There is no such option “enable VPLS” for a switch port. A switch has no idea what MPLS or VPLS is - it is a switch.

Mikrotik does have that option.

Well you are correct a switch is a switch unless it can transport large packets.

So what do the problem be here?

Sent from my SAMSUNG-SM-G935A using Tapatalk

No it doesn’t have that option. Where do you see such an option?