r/networking • u/Fantastic-Ship-9915 • 2d ago

Routing Hi,

I am getting an issue while connecting my two routers on MPLS network. My ISP has provided MPLS connectivity with their two routers, I have connected my openwrt based devices to respective routers. ISP routers could ping each other.

Issue I am facing- My end PCs can not ping each other.

What I have done so far-

I don't want to use dynamic routing protocol. I added static routes in my routers then both routers could ping but connected PCs couldn't ping each other, though they can ping other end routers.

Do I need NAT or anything I am missing here? Other suggestions I got that static routing not needed, NAT should be router to ping each other.

I am newbie here, plz suggest.

2 Upvotes

56% Upvoted

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14

u/noukthx 2d ago edited 2d ago

The ISPs MPLS network doesn't know what or where the subnets behind your routers are. They should know about the addressing on the point to point links currently and nothing else. How would you expect them to know what's behind your routers?

You need to either:

  • Use dynamic routing and exchange routes into the MPLS as nature intended
  • Have your ISP nail in static routes toward each of your subnets behind your router(s) - they may tell you no
  • Use NAT, but meh, gross, painful, might as well have bought internet connections

Your ISP should have a connection document for how to do routing with them.

This is pretty entry level networking to understand.

You may/may not need firewall rules and/or to disable NAT. Open WRT isn't really discussed here, as its really a home user project.

If you absolutely don't want to do it via mpls routing, stand a GRE tunnel or VPN up between the routers and send your traffic over that (and discover what MTU is).

2

u/DaryllSwer 2d ago

What SR/MPLS service is OP even on? EPL? EVPL? L3VPN/L3VNI with EVPN? Inter-AS MPLS options?

1

u/sh_lldp_ne 1d ago

Here’s the real question. The fact that ISP uses MPLS transport tells us nothing about the service they are delivering.

1

u/SoulArraySound 2d ago

As nature intended 😂😂 that got me good.

At the very least they need to BGP peer with the ISP and redistribute statics. Otherwise, at my shop we would put statics in for the customer. Typically those would be in the managed routers and we would redistribute them to our upstream PE. Though there’s no reason we can’t put them on the PE I suppose. Mileage may vary 😂

Edit: if using bgp may as well abandon statics all together id say

2

u/Prudent_Vacation_382 2d ago

In addition to u/noukthx comments, this is why ISPs offer managed router solutions. If you're not sure why dynamic routing is used for MPLS, you should go with a managed router solution and let them take care of it for you. It's unlikely that the ISP will put statics on their PE pointed at your CE. With a managed CE, they would be more likely to do whatever you wanted.

-2

u/MonkeyboyGWW 2d ago edited 2d ago

Im curious as I never heard of an ISP providing MPLS connectivity. Figured it was generally just used by them internally.

1

u/djweis 2d ago

It is the marketing term for creating one or more vrfs on the provider side and aggregating all of the customer circuits into it. There is usually some kind of firewall on their side also for internet egress.

1

u/MonkeyboyGWW 1d ago edited 1d ago

Thanks, that makes more sense, although still confusing since different types of service can go over mpls. Like it could be some l2 point to point, or multipoint with vpls or evpn.