Case Study: Taking advantage of switched Gigabit Ethernet technology

When Indigo moved its premises, it seized the change to redesign its entire network infrastructure, using the Gigabit Ethernet...

When Indigo moved its premises, it seized the change to redesign its entire network infrastructure, using the Gigabit Ethernet technology

Indigo, part of the Telecom Eireann Group and a major provider of Internet solutions to both business and domestic users, has just redesigned its whole network infrastructure to take advantage of switched Gigabit Ethernet technology. A recent move to new headquarters in the vibrant Temple Bar area of Dublin gave Indigo the ideal opportunity afforded by a green field site to upgrade its existing Fast Ethernet topology.

"We were bursting at the seams in our other site, so the problems we faced were ones of capacity as well as speed," explains Brian Boyle, network operations manager. "The move to the new headquarters has allowed us to completely overhaul our network infrastructure from the wiring up, and implement a fully switched topology with full Gigabit Ethernet backbone."

Indigo's R&D department was tasked with the job of redesigning the network, retaining the existing Cisco Catalyst units, while ensuring that functionality and current working practices could be maintained. "We wanted to future proof our network infrastructure to cope with an enormous increase in online demand," states Boyle. "Since December 1998, traffic levels have tripled as our market share has grown. The new infrastructure has avoided the potential bottleneck caused by such demand."

Indigo went out to the market and looked at every major company, including Foundry, and made its decision purely on a technical and financial basis. "Foundry gave us the best price/performance ratio," states Boyle. "We are fortunate in that we have a wealth of expertise in network design already in house. Our original specifications were only changed because features in the Foundry products allowed us to improve on our first plan."

A Gigabit fibre backbone was installed with Lucent Category 5E Gbit standard copper cable chosen for the flood wiring. Three Foundry Networks chassis-based FastIron II switches and a FastIron Backbone switch now sit at the very core of Indigo's operations forming a backbone linking mail servers, news servers, access servers, games servers and international bandwidth servers.

"This cluster of switches replaces our one central switch ( a Cisco Catalyst 5000 that has been deployed elsewhere on the network. We no longer have a single point of failure, or are limited by the amount of traffic the single switch could cope with," says Boyle. "Throughput has improved tremendously and we now have built-in redundancy. The main advantages for us, however, are the move to full gigabit switching and the scaling up of the number of available ports. Our total number of available ports has increased by a factor of five, and at very little additional cost."

As an ISP, Indigo has to employ advanced security procedures in order to control and restrict certain traffic throughout the network. "The Foundry switches allow us to use advanced techniques like server load balancing and transparent caching," says Boyle. "We are particularly interested in the Foundry transparent caching implementation. With a large customer base we simply can't manage everybody's caching requirements at an individual level. However, for some of our customers, transparent caching is an appropriate methodology, and Foundry gives us the option for selective implementation.

"We also needed to implement Access Control Lists ( basically a kind of packet filtering firewall technique that allows you to decide what has to be excluded from entering which part of the network ( but didn't want the performance restrictions associated with traditional routing software," explains Boyle. "The Foundry kit performs this task at wire speed, with no drop in performance. And, because it's hardware, it doesn't sit in the line of the incoming data, which is what normally causes bottlenecks."

The installation and implementation was trouble-free, and having the backbone in place proved invaluable in ensuring a seamless move from the old premises to the new. Fibre cable was used to link the new backbone and the old site. "The nature of our business meant we had to stay online during the move to the new premises," says Boyle. "Having the backbone meant that we could move gradually and without disruption to our customers."

Using a switched topology means that Indigo could deliver 100 Mbit/s Fast Ethernet to the desktop. "We still do the same things in the same way, except that the traffic just whizzes about the place," confirms Boyle. "Expansion is no longer an issue, and we haven't found any constraints in the switched solution, the infrastructure should be easy to grow as we develop. The beauty is that we can now shunt large amounts of data around and profile our traffic much better."

Profiling traffic is an important exercise for Indigo. It allows it to monitor access levels and evaluate trends in Internet usage. "If we understand who is trying to access what and when, this allows us to build up a larger picture of network usage, and then predict our growing needs, and add more resources where they are needed, but before they become critical and impact on performance," states Boyle. "We use a variety of home grown tools based on SNMP to monitor and manage our network. Even with the new topology and extra network devices, our management overheads have not increased. All the switches have integrated management modules that make our task much easier. Our head count is going up, but that is only because we are a growing company. There is also a lot of functionality and management capability in the switches that we haven't even started to look at yet, but will be of use in the future as traffic and demands grow further."

However Boyle does concede that network design is an art and a science stating, "Our basic network design was based on a lot of harsh experience - it wasn't derived from pure genius alone. We have learnt the hard way, not with this installation, but all the guys involved brought a lot of experience to bear, and that is probably why it went so smoothly."

By Linda M Davies

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