Mpls

rev_ollie

Hey!

Wanted to ask a few questions regarding MPLS. I'm getting the idea of it and can see why it has some speed improvements etc but just the main key points I need to establish.

If say I had 4 sites over a wide area - say global sites and I had an ISP who could cover them all.
The problem I have is this - say it used to be frame relay. There was a partial mesh of PVC's going to the sites and they were carrying voice.
If it was switched to MPLS - are the PVC's totally removed? Would they simply now be paying for the connection to the MPLS cloud?

I know that MPLS uses layer 2 and will probably be going over a frame or ATM network so is it simply the link to the cloud the organisation has and pays for?

Also in the cloud - redundancy wise are there multiple routes around the carriers network? with that in mind all the organisation has to worry about redundancy wise is the actual link at their end...maybe have 2 links to 2 different carriers...

Finally with the VPN's. Is all MPLS traffic sent through the customers VPN? I think it was on CBT nuggets the guy mentioned that the carriers devices have a virtual like routing table for each customer? So I take it customer routes, data etc travels through their own VPN in the cloud? Is that right...

I'm stuck in a frame world and want to get out!

networker050184

rev_ollie wrote: »

If say I had 4 sites over a wide area - say global sites and I had an ISP who could cover them all.
The problem I have is this - say it used to be frame relay. There was a partial mesh of PVC's going to the sites and they were carrying voice.
If it was switched to MPLS - are the PVC's totally removed? Would they simply now be paying for the connection to the MPLS cloud?

You may still have Frame Relay as your access into the MPLS network, but thats not very likely these days.

rev_ollie wrote: »

I know that MPLS uses layer 2 and will probably be going over a frame or ATM network so is it simply the link to the cloud the organisation has and pays for?

MPLS is used over an L3 backbone. Whether it goes over FR or ATM depends on how the providers network is built out. Most providers have moved away from ATM and Frame networks in favor of a L3 backbone running MPLS services.

rev_ollie wrote: »

Also in the cloud - redundancy wise are there multiple routes around the carriers network? with that in mind all the organisation has to worry about redundancy wise is the actual link at their end...maybe have 2 links to 2 different carriers...

The provider will usually have multiple paths through their network. Providers don't want a single node or link failure taking out a bunch of customers.

rev_ollie wrote: »

Finally with the VPN's. Is all MPLS traffic sent through the customers VPN? I think it was on CBT nuggets the guy mentioned that the carriers devices have a virtual like routing table for each customer? So I take it customer routes, data etc travels through their own VPN in the cloud? Is that right...

Yes, routing tables are separated per customer. All traffic will traverse a common backbone, but will be separated through the use of MPLS labels.

I think you need to sit down and do some more reading on MPLS. You don't seem to understand the basic concepts which is making it hard for you to visualize an end to end approach.

rev_ollie

Cheers for that, its definitely something I'm still reading up on.

Just a quick one on the main point. I take it instead of having a PVC through the network like you would with frame its simply a route to the providers edge and then data is routed from there?

I take it if that's true then how does it work in terms of the topology in the cloud. As you would in frame you would have say a partial mesh built up of PVC's. With MPLS is it simply a case of each site is connected and then the switched route built up?

Its annoying in that the physical work of it all - eg routes passing, how the tables are built and links labelled etc has gone in easy. Its just these little bits that I need to clean up.

networker050184

rev_ollie wrote: »

Cheers for that, its definitely something I'm still reading up on.

Just a quick one on the main point. I take it instead of having a PVC through the network like you would with frame its simply a route to the providers edge and then data is routed from there?

Yes thats how it would work.

rev_ollie wrote: »

I take it if that's true then how does it work in terms of the topology in the cloud. As you would in frame you would have say a partial mesh built up of PVC's. With MPLS is it simply a case of each site is connected and then the switched route built up?

Yes basically. The routers route between the PEs that the customer is connected to.

rev_ollie

Brilliant - its fitting in nicely now.

Its being stuck doing frame relay for so long that some areas have crossed over and confused me.
Just out of interest is there any good resources you recommend to pick this up? I'm not looking to go into to much detail yet - more on how its designed, implemented and the basic of how it all works.

networker050184

I like the MPLS Fundamentals book. It will probably go into a bit more detail than you want, but its an easy read and you can just read what you need.

rev_ollie

Ok cool - I will go and check that one out at the library and destroy my mind at the weekend.
Thanks for the tips - much appreciated!