Is the Extra Layer Better? Layer 2 Versus Layer 3 Networking

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L2 and L3 VPN channels – the differences between physical and virtual channels of different levels
Instead of logically tying the endpoint of the network tunnel to the physical IP address, each tunnel is bound to a permanently associated IP address at the device. And then I thought, this is a matter that I better delegate. In L2 VPN communication happens in the same way we do at our single site local network. There is no way to differentiate if something belongs to customer A or B. Keep in mind that your major penalty at L3 processing is coming from the fact that the frame has to be unpacked twice.

VRF (Virtual Routing and Forwarding)

Understanding Layer 2 VPNs

IPSec — IP Security, a network security protocol suite that applies to the data transferred over IP and uses packet authentication, encryption and integrity check mechanisms. It is important to note that modern network infrastructure is designed in such a way that a client only sees a part of it stipulated in the agreement. Dedicated resources virtual servers, routers, operational data and backup storages along with operating programs and memory content are completely isolated from other users.

Multiple physical servers can work simultaneously and consistently for one client, and the latter will see them as one powerful pool of servers. It works vice versa, too: In addition, the configuration of an L3 cloud network can be scaled up to almost any size which is the way Internet and large data centers are designed.

Dynamic routing protocols, e. OSPF, and others operating in L3 cloud network enable choosing the shortest routes for data packets and sending packets in multiple routes simultaneously to optimize the load and to extend the capacity of the channels. Modern communication channels and hardware used by providers can handle a large amount of information, and many dedicated channels rented by users are, in fact, underloaded.

L2 should only be used on particular occasions for specific tasks, and one should take into account the options of scaling this network in the future and consult with an expert. On the other hand, all other things being equal, L3 VPNs are more versatile and easy to operate. This review lists modern standard solutions used when relocating a local IT infrastructure into remote data centers. Each of those has its own pros and cons, its own clientele, and when choosing the right solution, you should focus on a particular task at hand.

In reality, both L2 and L3 of a network model work together and cover their own activities, which means that providers trying to differentiate those levels are playing a double game.

Also, all the service provider routes will have to participate with routing. The core of the service provider network P router will only do switching based on labels. First of all, our two customers are using overlapping address space. The PE2 router will learn There is no way to differentiate if something belongs to customer A or B.

To fix this issue, we will use a RD Route Distinguisher. We will add something to the prefix of the customer so that it will become unique:. The RD is a 8 byte 64 bit field. You can use any value you want but typically we use the ASN: We now have a method to differentiate between the different prefixes of our customers. By adding these values, we have unique VPNv4 routes. Take a look at the picture below:.

You may cancel your monthly membership at any time. The service provider must detect only how much traffic the Layer 2 VPN will need to carry. Customers must know only which VPN interfaces connect to which of their own sites. In a full-mesh topology between all three sites, each site requires two logical interfaces one for each of the other CE routers or switches , although only one physical link is needed to connect each PE switch to each CE router or switch.

A Layer 2 circuit is similar to a circuit cross-connect CCC , except that multiple Layer 2 circuits can be transported over a single label-switched path LSP tunnel between two provider edge PE switches.

The Junos OS implementation of Layer 2 circuits supports only the remote form of a Layer 2 circuit; that is, a connection from a local customer edge CE switch to a remote CE switch. When customer networks that use private addresses connect to the public Internet infrastructure, the private addresses might overlap with the private addresses used by other network users.

Two different VPNs can use overlapping addresses.

Pros and Cons of Layer 2 Vs Layer 3