Welcome to Bucaro TecHelp!

Bucaro TecHelp
HTTPS Encryption not required because no account numbers or
personal information is ever requested or accepted by this site

About Bucaro TecHelp About BTH User Agreement User Agreement Privacy Policy Privacy Site Map Site Map Contact Bucaro TecHelp Contact RSS News Feeds News Feeds

ISP Multihoming Explained

Internet access for organisations today is no longer about connectivity for email and web browsing. A stable Internet connection is a vital component in the chain of IT systems required to conduct business. Typically, in the past, the focus around Internet connectivity has been on cost, with vendors providing solutions allowing organisations to spread their traffic across consumer and enterprise products.

This approach is all good and well, and can provide significant cost savings, especially when employee traffic is directed over low-cost consumer products such as ADSL, however, when you are conducting B2B business through front end servers hosted in your DMZ, resilience becomes a major concern. In this scenario, a dead Internet link can mean loss of revenue and even, potentially more serious, brand damage.

In this paper we discuss a number of methods that can be used to improve the resilience of an Internet link. While this sounds like it should be a simple case of connecting to multiple Internet Service Providers, the devil as they say, is in the detail.

Mission critical Internet

Business networks have been mission critical for some time now and the focus on resilience and business continuity has always been top of any CIO's mind, however, the general areas of interest for this focus were restricted to internal networks and systems.

With more and more business being conducted either directly via the web or via B2B over Internet links to systems hosted in DMZ's, it is simply no longer permissible for an Internet link to be down. Loss of access to the Internet can have a direct impact on revenue generation, especially today as the business operating models begin shifting towards off site cloud computing and software as a service.

A solution to the problem

Multihoming is essentially a method whereby a company can connect to more than one ISP at the same time. The concept was born out of the need to protect Internet access in the event of either an ISP link failure or an ISP internal failure. In the earlier days of Internet access, most traffic was outbound with the exception of email. An Internet link failure left internal users with no browsing capability and with email backing up on inbound ISP mail gateways.

Once the link was restored so was browsing and email delivery. The direct impact to the business was relatively small and mostly not revenue effecting. Early solutions to this problem were to connect multiple links to the same ISP, but while this offered some level of link resilience, it could provide no safeguards against an internal ISP failure.

Today, however, most organisations deploy a myriad of on-site Internet accessible services such as VPN's, voice services, webmail and secure internal system access while also making use of business critical off site services such as software as a service (SaaS) and other cloud based solutions.

Furthermore, while corporate front-end websites are traditionally hosted offsite with web hosting firms, the real-time information on the corporate websites and B2B sites is provided by back-end systems based in the corporate data centre or DMZ. Without a good quality Internet connection, these vital links would be severed.

Varied requirements and complexity

That said, the requirement for multihoming are varied and could range from the simple need for geographic link diversity (single ISP) to full link and ISP resilience where separate links are run from separate data centres to different ISP's. While the complexity varies for each option, the latter forms the most complex deployment option, but affords the highest availability, with the former providing some degree of protection, but does requiring a higher grade of ISP.

A major component of the complexity comes in around IP addressing. The way the Internet IP addressing system works is that each ISP applies for a range of addresses from the central Internet registrar in their region. They would then allocate a range of IP addresses, called an address space, to their customers from this pool. It goes without saying that no two ISP's can issue the same address space to a customer.

RSS Feed RSS Feed


Follow Stephen Bucaro Follow @Stephen Bucaro


Computer Networking Sections

Fire HD
[Site User Agreement] [Privacy Policy] [Site map] [Search This Site] [Contact Form]
Copyright©2001-2018 Bucaro TecHelp 13771 N Fountain Hills Blvd Suite 114-248 Fountain Hills, AZ 85268