EPC backhaul networks

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1

Hi,

I would like to understand why there is a preference for L3 VPNs over
L2 VPNs for the EPC backhaul networks? We can use both layer 2 and
layer 3 VPNs for communication between the eNodeB and the MME or S-GW,
so why is it that most providers prefer L3 over L2.

Glen

2

Hi,

I would like to understand why there is a preference for L3 VPNs over
L2 VPNs for the EPC backhaul networks? We can use both layer 2 and
layer 3 VPNs for communication between the eNodeB and the MME or S-GW,
so why is it that most providers prefer L3 over L2.

There are just more companies offering L2 metroE than L3 in the backhaul
space. I have pushed for L3 but very few offer the speeds and reach
required

Cb

3

Becuase the lessons learnt in the last 30 years or so of networking is that large L2 domains are considered harmful. If you subnet them down in different vlans, it means for every new vlan you need to configure something on the MME/SGW.

It's just easier and safer to break it down into smaller L3 domains that you route between.

4

Could you please elaborate on what you mean by "reach" here?

5

/

There are just more companies offering L2 metroE than L3 in the backhaul

space. I have pushed for L3 but very few offer the speeds and reach
required

Could you please elaborate on what you mean by "reach" here?

The only way to reach 2000 cell sites in Chicago with 100megs of Ethernet
handoff is with L2 metroE. There is not a feasible L3 service offered
today.

6

It's also easier to troubleshoot when something goes boom.

Owen

7

Heard a lot about MPLS-TP to apply in this area. What do you think? Is it
for real?

Thanks!

Ping

8

MPLS-TP is great for SDH people, they don't have to learn anything new. It's the new SDH, just packet based instead of TDM. Everything else pretty much stays the same.

I'm sure this is very popular in some circles, I'm not a fan though.

9

Ah.

We either rent fiber or put up our own radio links, I guess different problems in different markets.

10

The only way to reach 2000 cell sites in Chicago with 100megs of Ethernet
handoff is with L2 metroE. There is not a feasible L3 service offered
today.

Ah.

We either rent fiber or put up our own radio links, I guess different
problems in different markets.

Yep. I hate L2. It is a total nightmare. But, it is literally the
only game in town. I blame the MEF for spreading propaganda that
MetroEis the best solution for backhaul ... most people dont even
think of L3 solutions.... all the telcos, cable-cos, and utilities in
this space only do L2 to the cell site.... even though they all use
the same Juniper and ALU gear that does L3 too ...

Cameron

11

Curious, do you think this will last? Thought LTE is all-IP. Why is there a
need for L2 other than raw bandwidth from Ethernet links?

Thanks!

Ping

12

Easier to troubleshoot is the main reason but also, you would not put the
MME/S-GW in every segment with the eNodeB anyways, so in the end you'd
really want a L3 routed solution between them. One of the things I've
seen is the L3 interface for the eNodeB terminates locally on an attached
smaller cell-site router via a /30 and is not part of a larger L2 service
with many eNodeBs in the same broadcast domain. You can run into scale
issues with L3 as well with a router at every cell site and dynamic
routing, so usually it's some kind of hybrid solution.

Most service providers who provide backhaul services for wireless
providers do so over a L2 or PW over MPLS network. Some of the smaller
ALU, etc. cell site routers have started to support L3VPN so maybe L3VPN
will be a service offering in the future with all-IP EPCs.

Phil

13

Yep. I hate L2. It is a total nightmare. But, it is literally the
only game in town. I blame the MEF for spreading propaganda that
MetroEis the best solution for backhaul ... most people dont even
think of L3 solutions.... all the telcos, cable-cos, and utilities in
this space only do L2 to the cell site.... even though they all use
the same Juniper and ALU gear that does L3 too ...

Curious, do you think this will last? Thought LTE is all-IP. Why is there a
need for L2 other than raw bandwidth from Ethernet links?

They're talking backhaul between the node-b base-stations and the radio
network controller...

All the traffic from the handsets is encapsulated between those two
points so it's link and network layer agnostic.

14

I work for a MSO and while we do provide L2 services today for wireless
backhaul, the services are based on requirements from the wireless
providers and I haven't seen an RFP yet in which someone wanted a L3
service. If someone really wanted a L3VPN as a backhaul solution we could
oblige them but most do not want us having anything to do with their L3
network so we provide VPLS and P2P services. I'm always wary when I see a
wireless provider wanting to build a 500 site VPLS to carry traffic and we
try to discourage them as much as possible, but it happens...

Phil

15

I know some people that are starting to refer to it as the Meth Forum.

Owen

16

Write the RFPs asking for L3 -- I don't think they're asking for L3.

Frank