1. hSo's Guide to
Understanding MPLS
All you need to know about MPLS
hSo:you can do what you need to do

2. Legal Disclaimer
This free guide is provided with the understanding that HighSpeed Office Ltd (aka ‘hSo’) and its employees are
not providing professional advice or services to you.
This document is a guide to MPLS. It is not a comprehensive guide to the subject.
Before taking any action or making any business decisions on the basis of this document, you should take
specialist professional advice from a competent professional.
Copyright Notice
© Copyright 2008 HighSpeed Office Limited, trading as hSo.
No content from this guide, including trademarks, may be copied without approval. Neither this guide nor
materials from it may be publicly displayed or distributed for any public or commercial purpose.
hSo Guide to Understanding MPLS Page 2 of 11

3. Table of Contents
Legal Disclaimer .......................................................................................................................... 2
Copyright Notice ......................................................................................................................... 2
Table of Contents................................ ................................ ................................ ........................ 3
MPLS in a Nutshell ...................................................................................................................... 4
How to tell if MPLS is relevant to your business ............................................................................ 5
The benefits of MPLS .................................................................................................................. 6
The secrets most MPLS Service Providers hide from you .............................................................. 7
MPLS doesn’t always offer a benefit......................................................................................... 7
You don’t need expensive MPLS hardware to get an end-to-end MPLS solution........................ 7
Typically you need at least three sites to make an MPLS IP VPN worthwhile .............................. 7
Many MPLS solutions are dependent on just one carrier ........................................................... 7
Some ‘MPLS’ Providers don’t actually have an MPLS network of their own................................ 8
Providers make mistakes, causing unnecessary downtime ................................ ........................ 8
Sluggish performance? Perhaps you don’t need a bigger pipe................................................... 8
Things to consider when picking an MPLS Solution Provider......................................................... 9
MPLS VPNs ................................ ................................ ................................ .............................. 10
hSo’s MPLS Solutions ............................................................................................................... 11
hSo Contact Details................................................................................................................... 11
hSo Guide to Understanding MPLS Page 3 of 11

4. MPLS in a Nutshell
Multi-protocol Label Switching (MPLS) is a method of getting packets of data to where they’re supposed to
go, by wrapping them in one or more labels, then forwarding them based on those labels (rather than their
contents).
The information contained in the label can be any type of data, but typically it would be IP packets and
Ethernet frames.
hSo Guide to Understanding MPLS Page 4 of 11

5. How to tell if MPLS is relevant to your business
MPLS is probably IRRELEVANT if…
û You only have one office , with no ‘back up’ data connection
û Your only use your connections for one type of traffic (e.g. web surfing, with no site-to-site
connectivity, no VoIP phone calls)
û Your main offices are connected solely via contended ADSL
MPLS is probably RELEVANT if any of the following hold true …
ü You have (or plan to have) three or more offices network ed together
ü You have one or more VPNs , or plan to
ü You use VoIP (Voice over IP), or plan to
ü WAN/Internet Access/Telephony downtime would cost you lots of money in terms of lost employee
productivity
ü You already pay for a few dedicated connections such as leased lines for internet access, ISDN trunks
for your phone calls, site-to-site connections to link your offices together.
hSo Guide to Understanding MPLS Page 5 of 11

6. The benefits of MPLS
Improved uptime (from ultra-fast re-routing) – if a major link within the MPLS network goes down, and an
alternative path exists, traffic can be re-routed down such a path in under 50 milliseconds. In other words,
there can be a major outage, but you wouldn’t notice a thing as the network detects and works around the
problem, in one sixth of the time it takes to blink an eye.
Cost-effective, scalable IP VPNs – forget complex meshes of tunnels between your various sites. MPLS IP
VPNs make it far simpler to set up a scalable VPN, and to add new sites to an existing one. You don’t need
additional hardware, such as expensive firewalls. All you need is standard routers.
Improved experience from your VPN (thanks to different Classes of Service being applied to customer-defined
prioritised classes of VPN Traffic) – instead of all traffic being treated as being of equal priority, the appropriate
Quality of Service settings can be applied to traffic within your WAN, so that time-sensitive traffic is assigned
priority over delay tolerant traffic. For example, if the inbound traffic to your head office from your remote sites
maxes out your Head Office’s connection, the traffic from your sites is prioritised in accordance to your wishes
(e.g. phone calls might be prioritised above application traffic to a key server, which might be prioritised above
web traffic, which might be prioritised above email).
Greater bandwidth utilisation within the WAN – the traditional way of ensuring Quality of Service within the
WAN is to create virtual circuits dedicated solely to particular streams of delay-sensitive traffic (such as phone
calls and site-to-site connectivity). This works, but is not ideal, as the circuits are underutilised for most of the
time. MPLS allows prioritised Classes of Service; this is a far better way of achieving the same Quality of
Service experiences, as the underutilised bandwidth can be used by other services when the services that
have a higher priority aren’t using it.
Virtual Private LAN Service (VPLS) allows multiple sites to be joined together as though they were on the same
LAN – , your Birmingham, Manchester or Leeds offices can be as easy to connect into your LAN in your
London office as the three PCs in the next room.
Quicker & easier service provisioning and upgrades – with MPLS there’s no need to manually set up routing at
every hop through the core network. The upshot is that the lead time between you placing your order and it
being delivered may shrink. The time between you ordering an upgrade and it being delivered may also shrink.
Less network congestion – congestion can mean that the shortest path between two points may not be the
best one for data to be sent along. MPLS offers sophisticated Traffic Engineering options that enable traffic to
be sent along atypical paths, bypassing congested areas of the network. This re-routing also relieves the
congestion somewhat.
hSo Guide to Understanding MPLS Page 6 of 11

7. The secrets most MPLS Service Providers hide from you
MPLS doesn’t always offer a benefit
MPLS only offers a benefit where there is network congestion, alternative paths or complex paths.
MPLS offers the benefit of prioritising traffic to ensure Quality of Service. But if there’s no network congestion
at any place or at any time, there’s no need for prioritisation, and Quality of Service will look after itself.
MPLS offers ultra-fast re-routing. But if there’s only one path available, there’s nowhere to re-route the traffic
to.
MPLS makes the job of configuring complex paths across a network quicker, easier and less error-prone. If
you’re dealing with a short path that touches few routers, there’s no real benefit.
MPLS makes a great deal of sense on carrier and provider networks. Their networks have alternative paths , so
can benefit from fast re-routing and traffic engineering. They have to ensure Quality of Service in the face of
network congestion, so they benefit from traffic prioritisation. They have to configure complex paths across
their network, so they benefit from the simpler configuration offered by MPLS. When their network reliability
and Quality of Service improves, so does the service their customer’s receive.
MPLS isn’t a magic bullet for use in all circumstances. If you have a single dedicated circuit from your office to
the edge of your service provider’s network, there would be no point in you using MPLS in that link. There’s no
network congestion within a dedicated connection, so MPLS’s traffic prioritisation would offer no benefit. A
single dedicated circuit is on its own i.e. there’s no alternative path, so MPLS’s fast re-routing would be of no
benefit. The journey is a single hop, so MPLS wouldn’t make the path easier to configure. It would just
increase your hardware bill.
You don’t need expensive MPLS hardware to get an end-to-end MPLS solution
In many cases, you’d be better off with letting MPLS begin and end at your provider’s end of your dedicated
circuits. As we explained above, you don’t benefit from running MPLS over a single dedicated link to your
provider’s MPLS hardware. It would add cost, but no benefit.
Typically you need at least three sites to make an MPLS IP VPN worthwhile
If you’ve got a single site and a dozen homeworkers, an MPLS IP VPN offers no benefit relative to a standard
VPN solution.
If you’ve got two sites, you would probably be better off with a LAN-extension service rather than an IP VPN.
Many MPLS solutions are dependent on just one carrier
In other words, if one of the fibre-optic-network -owning companies carrying your data suffers a network-wide
problem, all your sites could go down, simultaneously. If you want to avoid putting all your eggs in one basket,
ensure you get a carrier-independent solution.
hSo Guide to Understanding MPLS Page 7 of 11

8. Some ‘MPLS’ Providers don’t actually have an MPLS network of their own
They just put together circuits from carriers who do have their own MPLS networks. Ask whether the solution
provider has their own MPLS core network. If they haven’t, there’s a danger that many of the Quality of Service
and resilience benefits will be lost when they encounter congestion in the core network, or when links fail (and
the fast-rerouting provided by MPLS isn’t available).
Providers make mistakes, causing unnecessary downtime
Network engineers are human; they make mistakes just like everyone else. Assiduous record-keeping, checks
and processes help reduce those mistakes, but rare mistakes can impact vast numbers of customers. T he
only way to eliminate the mistakes is to remove manual intervention. When MPLS providers talk of ‘increased
resilience’ they’re not just thinking about fast re-routing in the event of an outage, they’re also thinking of how
MPLS will reduce the scope for human error. Traditionally, network providers would configure VLANs (virtual
LANs), running across the core of the network, changing the routing configurations at each leg of the journey.
That works, but it provides numerous opportunities for human error. MPLS moves the intelligence to the edge,
and makes the routing within the centre far simpler; this reduces the scope for errors, and makes it far easier
to provision dedicated bandwidth across the core.
Sluggish performance? Perhaps you don’t need a bigger pipe
Perhaps you just need for the traffic on your connection to be prioritised, according to its time-sensitivity and
importance, so that a dozen staff simultaneously viewing a humorous YouTube video doesn’t slow down
access to your work-related web applications for the rest of your staff.
hSo Guide to Understanding MPLS Page 8 of 11

9. Things to consider when picking an MPLS Solution
Provider
Carrier independence
By using a range of different suppliers to provide the circuits underpinning your network you gain:
• Greater resilience (network
failures that hit a particular carrier rarely affect the networks of other carriers. Using different carriers
for primary and backup links improves your network’s resilience)
• Better pricing (the carriers
are forced to compete for the business rather than getting it handed to them on a plate)
• Quicker delivery
(some carriers may be able to deliver quicker than others, as a result of already having fibre optic
cable going into the building in question, or to somewhere close by)
The best way to ensure carrier independence is to get your MPLS service through a Virtual Network Operator
(VNO).
That way, you get one point of contact, and one company to ensure the various circuits from the various
carriers are configured to work seamlessly together.
Going directly to carriers cuts out the middle man (the VNO), but isn’t usually cheaper as VNOs buy a lot of
circuits so benefit from volume discounts that aren’t available to end-users.
Is it end -to-end MPLS or MPLS in part?
When providers boast about MPLS, it’s worth checking whether they have an MPLS-enabled core network of
their own. Some don’t and are merely tacking together a patchwork of circuits from MPLS-enabled carriers.
That’s fine if all your circuits are coming from the same carrier, but if you want carrier independence and
MPLS, you need to pick a provider who has MPLS in their core network, and can provide an end-to-end
MPLS -enabled solution.
Solutions, not circuits
It’s possible you don’t really want MPLS-based circuits at all; you just want a solution. Rather than looking for
site-to-site connectivity from one company, internet access from another, VPNs from a third and phone
services from a fourth, it makes far more sense to find one provider who can deliver all of those elements. That
way, you get a best-of-breed solution w ithout losing accountability . Whenever there’s a problem, it will be
clear who is responsible for fixing it.
Managing one supplier is also easier than managing four. You no longer have to deal with different helpdesks
or act as a go-between for various suppliers.
A typical example of a solution would be a business putting a 10Mbps circuit from its HQ to a service provider
and from each of its major offices to that service provider. That 10Mbps could be used for delivering 2Mbps of
internet access, phone services (e.g. using SIP to make and receive calls), and carrying WAN traffic from the
four other offices. If the company wanted to double the internet access to 4Mbps, the additional bandwidth
would be provided over that existing circuit, allowing a fast upgrade.
hSo Guide to Understanding MPLS Page 9 of 11

10. MPLS VPNs
There are three main ways VPNs are provisioned over MPLS
Layer 2, VPWS Layer 2, VPLS Layer 3, IP VPN
Use Linking the LANs of Linking the LANs of Linking the LANs of
two offices. multiple offices multiple offices
together together
Think of it as… a long wire an Ethernet switch your very own small
into which network private internet
cables from other
offices are connected
Transports Usually Ethernet Ethernet frames IP packets
frames
Topology Point-to-point Multi-point Multi-point
(i.e. any-to-any) (i.e. any-to-any)
Data is… Switched Switched Routed
Scalable for linking Absolutely not! Yes Yes
lots of offices
together
Routing is You You Your Provider
managed by… (less control, easier)
Additional Hardware Router Router None
Required
You’ve got 7 offices, 14Mbps or more, Your choice Your choice
each with a 2Mbps regardless of usage
VPN connection to
HQ. How much
connectivity do you
need to buy at HQ?
hSo Guide to Understanding MPLS Page 10 of 11

11. hSo’s MPLS Solutions
hSo creates tailored IT and Telecoms solutions.
We combine the carrier-independence and value-for-money of a Virtual Network Operator with the technical
benefits of our fully-resilient MPLS core platform.
Our network provides:
• A low latency, zero hop MPLS core
• Fully resilient infrastructure
• Multiple services – connectivity, internet access, IP telephony
• Secure VPNs without the need for expensive additional equipment
• Quality of Service, delivered through MPLS Class of Service options
• Service Level Guarantees
• Bespoke bandwidth allocations to match your actual requirements
• Internet resilience with multiple global carriers and interconnects at multiple locations
• 24/7 pro-active network monitoring, including 24/7 telephone support
• Secure Assurance options to protect user experience.
• End-to-end MPLS solutions, where appropriate.
hSo provides solutions for The Salvation Army, Trinity Mirror, New Star Asset Management, Endemol and
hundreds of other organisations.
To find out more, give us a call on 08700 638 739.
hSo Contact Details
+ hSo, Epworth House, 25 City Road, London, EC1Y 1AA
( 08700 638 739
8 http://www.hso.uk.com
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