Servicing the city

Ethernet is adding a whole new set of cost, delivery and service benefits to the deployment of metropolitan area networks.

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By  Zoe Moleshead Published  October 5, 2002

Ethernet in the MAN|~||~||~|The sheer amount of data generated by today’s enterprises, combined with the deployment of evermore bandwidth hungry applications is putting an increasing strain on enterprises’ local area networks (LANs). While wide area networks (WAN) can offer relief to overburdened LANs, the additional capacity does not necessarily justify the cost. However, this divide is now being filled by metropolitan area networks (MANs).

“The beauty of MANs is that they blur the difference between LANs and WANs. Typically, the bandwidth available on the internet is vast, whereas bandwidth availability inside a business [network] is limited. This leads to a huge bottleneck where data from the internet attempts to squeeze through into the enterprise. MANs act as a bridge between the two removing this bottleneck,” says Doug Adams, director worldwide channels, partnerships & alliances, 3Com.

While MANs are not in themselves new, the introduction of Ethernet into metropolitan area network has brought an additional set of cost, delivery and service benefits. Traditionally, SONET/SDH or ATM formed the core of MANs, however, the technology can be expensive, inflexible and difficult to deploy.

“Ethernet MANs (eMANs) offer service providers much better return on their investment and the cost for the user is much lower than other types of MAN technology, such as ATM or SONET,” continues Adams.

With SONET/SDH, users can only deploy bulky E1 or T1 circuits, which means they are often paying for additional bandwidth that they do not require. However, service providers can ‘chop’ Ethernet MANs, delivering bandwidth and network speeds tailored to the requirements of a particular customer.

“If a customer wants to be connected on a 100 M/bit port we can chop the bandwidth and make it 100 M/bit, or if the customer wants 2 M/bit or 16 M/bits that can be done as well with Ethernet,” explains Emad Makiya, general manager, Extreme Networks, Middle East & North Africa.

While SONET/SDH was designed primarily for handling voice traffic, Makiya says that Ethernet is more than capable of balancing the bandwidth requirements of both data and voice networks.

“If you look at the traditional MAN that was built by the telcos, companies like Etisalat, Egypt Telecom or AT&T, you will find SONET or SDH infrastructure in there. These networks are designed to carry voice traffic, if they go and run data on top of it, it will consume all of the bandwidth,” he comments.

The ability to run both voice and data over one network not only forces down costs, but also broadens the services that can be delivered via the network. In the case of Ethernet MANs, voice over IP (VoIP), video-on-demand and multicasting are added to traditional voice and internet services. Etisalat, for example, is investing in metro area networks to distribute cable television services throughout Dubai and Abu Dhabi.

“Etisalat is planning to provide Ethernet-based integrated services in Dubai and Abu Dhabi to provide multiple services, such as E-Vision’s cable TV services, Emirates Internet Multimedia’s (EIM) internet access and VoIP services,” says Issar Al Haddad, general manager, network development, Etisalat.

For Etisalat, the benefits of implementing eMANs are threefold; reduced costs, increased scalability and a simplified network infrastructure.

“The key advantages of deploying these Ethernet-based networks is cost, integration of services and the speed of deploying new services. Ethernet technology… can also cut down on multiple layers of network. Once an Ethernet-based network is in place, adding or changing services can be done by the touch of a button,” explains Al Haddad.

||**||Service delivery|~||~||~|MANs’ flexibility, service delivery and ability to cover large ‘city’ areas were also key factors for Dubai’s Internet and Media City Free Zone and Egypt’s residential, office, shopping and hotel complex, Citystars.

Aside from offering Dubai’s free zone a single converged network for its voice, data and video requirements, the eMAN can also be divided into virtual local area networks (VLANs) to deliver services to customers.

“We have a metropolitan Ethernet network that runs all our services — voice, data and video — on one single converged network,” says Farid Faraidooni, director of telecom, Dubai Technology, Electronic Commerce & Media Free Zone Authority.

“We provide customers with a practical IT & telecoms services. One of these is VLAN services, which will carry the same voice and data and very soon video services [as the eMAN,]” he adds.

For Citystars’ in Cairo, which currently has over 11,000 VoIP systems running on its MAN, the flexibility and scope to add future services is also critical.

“[The MAN is] able to cater for 2000-plus end user companies and it allows users to have the bandwidth they need. It also provides a network that is flexible to the integration of future technologies,” says Hamdi El Siah, a systems engineering manager at Cisco who was involved in Citystars’ MAN implementation.

MANs also offer similar benefits to enterprises, enabling them to deliver bandwidth intensive applications to distributed offices in a cost efficient manner. Enterprises are, however, dependent on service providers for the deployment of MANs.

“You can operate a MAN through a service provider, using their existing equipment and infrastructure. Alternatively, you can lease fibre lines and create your own MAN between different locations in the same geographic area. This would still need to be connected to the outside world via a service provider, but only at one of the locations,” explains 3Com’s Adams.

Lebanon’s Ogero Telecom capitalised on its position as the IT administrator for the Ministry of Telecommunications (MoT) to ensure that it had access to the fibre channel it required for its MAN. The operator was also impressed by the timely delivery of the network, which was deployed with the help of Ericsson in less than three months.

With no public data infrastructure in place in Lebanon, the metro network, based on technology from Extreme Networks, offered the most effective way to link Ogero’s 57 core and 36 access sites.

“Lebanon is a small country and there is no public data network, so a MAN was the most suitable and comprehensive network to fulfil the requirements of Ogero. At the same time it covers the whole country in a cost efficient way,” comments Roger Aramouni, marketing & sales manager, MoT, Ericsson Lebanon Communications SARL.

As regional enterprises increasingly migrate to Gigabit Ethernet in their LANs, eMANs also offer users the opportunity to capitalise on the benefits of running Ethernet throughout their network infrastructure, which reduces overheads.

“Everything is going Ethernet, so users will have the same frame that runs from the desktop to the service provider. If users have an infrastructure that is end-to-end Ethernet, they will minimise the overheads on the packets that are being to transferred from one network to the other,” explains Extreme Makiya.

Reduced overheads are not the only benefit of running Ethernet from the LAN to the WAN, the technology also reduces the need for additional skills as most network engineers are already well versed in Ethernet, and can apply the same knowledge to eMANs as they do to other Ethernet networks.

“Ethernet is not really a new technology — it has been there for quite sometime and most of our customers understand these technologies. However, the way that we implement MANs is to tie it up with the services, so there is a certain understanding of these technologies that needs to be addressed,” says Rony Atallah, consulting engineer, Cisco Systems, Dubai.

||**||Vendor developments|~||~||~|While local service providers and enterprises have begun to evaluate the benefits of implementing metro networks, vendors have been working to develop products that deliver advanced network and management features.

Both Foundry Networks and Cisco espouse the benefits of their respective switching solutions, stressing that they no longer merely act as Layer 2 switches, but are also capable of delivering the Quality of Service (QoS) and IP routing services of Layer 3 and 4 switches.

“The switches in the metro arena are becoming multi-layer switches, meaning that the switch can handle Layer 2 as usual, but can also handle Layer 3 and Layer 4. What I mean by Layer 3 and Layer 4 is the switches can now route traffic based on Layer 3 — they are IP aware — and they can decide where the traffic should go and route the traffic based on IP,” explains Atallah.

Additionally, Foundry claims that its NetIron range of metro routers can provide improved levels of traffic monitoring and engineering.

“The Foundry offering ranges from Layer 2 MANs, Layer 3 MANs to MANs utilising MPLS (multiprotocol label switching) for both traffic engineering, as well as Transparent LAN services (TLS). This coupled with sFlow accounting gives wire speed usage-based accounting and traffic monitoring at Layer 2 or Layer 3,” says Yarob Sakhnini, regional technical manager, Foundry Networks.

Bringing Layer 3 and 4 functionalities into the metro network is a critical factor in facilitating the delivery of services such as video-on-demand, multicasting or VoIP. The added capabilities allow users to allocate and manage bandwidth for these services more effectively.

“A switch can be configured in such a way to better handle VoIP traffic and provide quality of service,” says Atallah.

“We already have customers in the Middle East trying technologies, such as multicasting, video broadcasting and video-on-demand on these switches,” he adds.

Resilience is also a key factor in the deployment of eMANs, if users are running mission critical applications or transferring data across over the network they cannot afford any downtime or loss of service. While SONET/SDH has always been considered a highly reliable technology, Extreme’s Makiya says issues concerning Ethernet’s resiliency have been addressed, putting it a on par with SONET/SDH technology.

“If you look at a SDH/SONET network, it is very powerful, phones never go down and if you pick up the phone you always get a service. The same thing has been done with Gigabit Ethernet-based MANs. Optical rings have been built in metro cities to provide the same kind of resiliency, at around 70 milliseconds,” he explains.

However, careful planning is also critical to ensuring the efficiency and success of MAN deployments. Enterprises need to address issues such as coverage, number of users and services, prior to implementation.

“There are other aspects involved in setting up a metro network — enterprises have to set up a security policy, they also need to plan how many users they are going to have in a neighbourhood because they need to know how much port density they have to plan for, and scalability is an issue as well,” comments Makiya.

Users also need to examine the coverage area for the MAN, factoring in the distance that their respective networks are expected to span. As Foundry’s Sakhnini explains, “in terms of distance, LANs typically span fewer than two km. While MANs can cover distances up to 150 km, the WAN extends beyond the MAN, typically spanning farther than 150 km.”

Enterprises also need to investigate where fibre is laid in regard to their buildings because, while eMANs can be easily deployed if there is already fibre in place, having to lay fibre is trickier, and again dependent on the service provider.

“Ethernet metropolitan networks can be easy to deploy in areas where fibre has reached most of the buildings. In other places where fibre is not so abundant, the deployment may be more difficult,” says Etisalat’s Al Haddad.

With the costs savings, simplicity of use & deployment and feature rich services that eMANs can deliver, it is no great surprise that vendors are reporting increasing interest in the technology from around the Middle East. According to Atallah, Cisco already has eMAN projects in place or underway in Qatar, Bahrain, Egpyt, Saudi Arabia and the UAE. As such, it only seems a matter of time before the region’s service providers ramp up their implementations and push the benefits out to the Middle East’s end users.
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