Point to Point Leased Line – Direct Connectivity Between Two Sites
There are two main ways to link two sites together with a leased line.
One is to use a point-to-point leased line. The other is to use a somewhat more complicated topology.
Typically if you want to link two locations together your provider will get two leased line circuits. One from Point A to their nearest data centre to point A, and another from Point B to their nearest data centre to point B. If the nearest data centres to Points A and B are different, the provider will connect the middle bit using their core network, a high bandwidth ultra-resilient network linking key locations.
For most users, a point-to-point leased line has a number of drawbacks relative to the above network topology.
One is that if your leased line doesn't touch your provider's network, they can't monitor it. If it goes down, they won't know.The onus will be on you to spot the downtime, and report it to them, so they can in turn report it to the carrier responsible for your circuit.
Secondly, if your connection doesn't touch your provider's network your leased line provider can't add commonly requested services to it, like Internet access or SIP telephony.
And finally, if you want to add another site to your two site WAN, it'll be problematic. You'll either need to pay for TWO additional point-to-point leased lines (New site to point A, New site to Point B), or traffic between two of your sites will need to pass through the other one, hogging much of the bandwidth.
If you want staff to be able to connect to their work PCs (or servers) from home, you'll also be out of luck. As your point-to-point leased line doesn't touch the Internet, you can't receive inbound VPN connections, even if you've got the firewalls and VPN clients in place to support IP VPNs.
For all these reasons, most leased line providers are inherently suspicious when someone says they want a point-to-point leased line. They wonder "Does this person REALLY want a point-to-point leased line? Do they understand what this means, i.e. no Internet access on the leased line, no monitoring, an expensive to scale WAN?"
Most customers are better off getting a solution that passes through their leased line providers network. This doesn't necessarily mean that they'll SEE the traffic passing through the network. For example, providers with MPLS-enabled core networks can set up pseudo-wire services that make the providers data centre / core network hardware appear invisible. The point-to-point leased line can act just like an Ethernet cable. A very long Ethernet cable.
Some customers prefer the idea of a 'direct' connection from A to B. What they often fail to realise is that there really isn't a cable going directly from site A to site B. Instead there's a cable going from Site A to Site B, via Sites C, D, E, F and probably Z. Those other sites are merely invisible to you.
Most people don't realise just how geographically concentrated the major carriers networks are. For example, when one BT building in central London was hit by fire, there were outages affecting services at over 400 UK telephone exchanges (about 7% of all UK telephone exchanges).
The secret to getting a resilient service is not to swap from one major carrier to another, but to ensure that you have two connections to each site, and that each should use a different carrier's network.
There are some organisations for which point-to-point leased line connection may be appropriate. These include WAN network providers, ISPs, data centre providers, hosting companies, IP Telephony firms and Investment Banks. These sorts of firms typically order very high capacity links (1Gbps+), they have full-time network engineers on staff, and they have monitoring tools that enable them to spot circuit down-time for themselves.
Point to Point leased lines that do not touch your lease line providers network are marginally cheaper than the traditional WAN setup, in that fewer connections need to be bought to create a two site solution. But if you need to extend the solution, this rapidly ceases to be the case.
In theory, point-to-point leased lines also offer greater privacy, as only the carrier gets to see your traffic. Your leased line provider has no visibility of your traffic, as your connection never touches their network. However, in reality, unless your a major financial institution, this isn't something you need to worry about.
Anyone who wants to steal your data would probably try to attack you using social engineering, custom phishing attacks and drive-by malware. Trying to hack high-end network hardware would be a thankless task in comparison.