Virtual Private LAN Service (VPLS) and Multiprotocol Label Switching (MPLS) are both ways to manage and divert network traffic. They’re not not mutually exclusive, each with pros and cons. Let’s look at how VPLS and MPLS work and how they can benefit your own networks.
If you are an end-user operating a third-party network or VPN service then you shouldn’t need to worry - the decisions about which data-routing method to use have already been made by your network admin.
MPLS: Multiprotocol Label Switching
MPLS is a protocol that uses virtual ‘labels’ to forward packets of data over a backbone network. It works by creating temporary local labels for IP addresses using an Label Edge Router (LER), to which they’re mapped. Packets are transmitted and received along “pseudowires”, emulating direct point-to-point connections.
This may sound overelaborate but is extremely efficient. Labeling data in this way, as opposed to traditional IP routing, makes it very easy to differentiate between types of traffic, such as that belonging to different users. Labels can also help determine the most efficient pseudowire routes over which to send data. This is particularly useful when thousands of devices are using the network at once.
This was (and is) a huge improvement over traditional forms of IP routing, which tended to use software lookup tables and require that each data packet be scanned and forwarded individually. These requirements slowed down networks and made scalability very difficult.
Using MPLS also speeds up network performance. IP data packets only need to be assigned a special label when entering or leaving the network. Once inside an MPLS domain, the label itself can simply be changed by an Label Switch Router (LSR), massively speeding up packet forwarding and processing.
MPLS isn’t as vital as it used to be. Computers have become much faster these days, through use of ASIC (Application Specific Integrated Circuits). Modern machines can use IP routing tables more efficiently than when the protocol was first developed in the mid-1990’s.
MPLS still has its uses though, given that it supports multiple protocols and can easily be used to establish encrypted tunnels for VPN services. It’s also vital to any organization who wants to manage their various networks by VPLS.
VPLS: Virtual Private LAN Service
A VPLS makes use of both MPLS and VPN protocols to connect multiple LANS (Local Area Networks) over the Internet into one combined network. This is much more efficient than old fashioned shared networks using private telephony lines.
VPLS operates by creating a virtual ‘switch’ at the customer’s edge (CE) and the provider’s edge (PE) of their respective networks. This is done using the ubiquitous Ethernet protocol, so users can interact and share resources for all intents and purposes as if all devices were connected to the same LAN.
Layer 2 VPNs (L2VPN) can connect in this way, whilst maintaining control of their network and routing policies.The advantage, particularly to large organizations with multiple sites, means there’s no need to set up software individually in each location. It also becomes easier for org-wide communications, rather than set up multiple manual “point to point” connections.
VPLS vs MPLS
Although VPLS allows sharing of a core network infrastructure across multiple sites, individual LAN administrators can take comfort from the fact that VPLS operates on layer 2 of the OSI Model - the data link layer, not Level 3 - the network layer.
This lets LAN admins retain control of their own routing policies, a more secure arrangement, letting them add new devices to the LAN without going through a central server. It’s even possible to design separate connections for different applications within their home networks. However, this can cause security/scalability problems if individual network admins don’t keep their software up to date to support the latest protocols.
Generally, MPLS is considered to be the most scalable. It doesn’t rely on a particular protocol and can handle multiple types of network traffic. The use of Label Switched Paths (LSP) means it’s perfectly good for networks with many different types of devices as it’s extremely efficient at getting data where it needs to go.
This is partly because when using MPLS, the network can prioritize certain traffic. For instance, if your organization uses video conferencing software, you’d want to make sure data packets for meetings are sent and received as fast as possible as they happen in real time. Using labels makes it easy to manage traffic by prioritizing some while downgrading others.
If a particular data path becomes congested, labeling lets an LSR simply calculate a new “pseudowire” route for it to follow. This efficiency comes at a price however: MPLS doesn’t contain any default way to secure your network data. It means less granular control over your security. You can still encrypt data between routers, for example, but this must be managed by yourself.
Choosing communication protocols
As you’ve now discovered VPLS is not itself a communication protocol but a method. MPLS can be used to link together multiple networks to share resources. So, neither VPLS or MPLS are really in competition.
Using a VPLS means you can benefit from the efficiency and speed of MPLS. But you can also keep your shared local networks as secure as a well-implemented VPN (and some free VPNs). This has the advantage of being able to transport both IP and non-IP traffic.
It’s not so much a case of choosing between VPLS and MPLS as discovering more about how they can complement each other and help your organization to share resources. If you only have a few sites or don’t want the trouble of setting up your own network, consider using cloud apps instead for your organization.
