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Wired LANs

Powering the inner circle

Is Cat 5 still a viable option when it comes to LANs? What is the status of the much touted Cat 7 standard? How far (or close!) are Gigabit Ethernet, fibre to the desktop and 10 Gigabit over copper from India's corporate LAN? Read Network Magazine's status check on the wired Indian enterprise LAN and find out. by Anil Patrick R

It is essential that the chosen cabling is viable for about 10 to 12 years. Therefore, the parameters to watch out for are future proofing, available bandwidth, and ease of integration
Shirish Gariba, VP-IT, Elbee Express Limited

No matter what the cutting edge advances in wireless technology are, the wired network is still the connection of choice for India's enterprise LANs. Wired networks lead when it comes to parameters such as performance, costs, manageability, and information security. This is because wireless technology is still immature and has a long way to go before it becomes the nemesis of the wired LAN.

Copper and fibre are the two media that come to mind when we think of wired LANs. What is new in these technology arenas? Which are the copper and fibre technologies in vogue? Read on for an update on what is in (and what is not!) in wired LAN and campus connectivity.

Let us start with the parameters to be kept in mind when choosing the technology to be used in the physical layer of your network. This will help us maintain a proper perspective while evaluating the various technologies available.

root@lan: wired

It should be possible to use the cabling infrastructure for long enough to maximize return on investment. That is critical because establishing a cabling infra-structure involves sizable investments.

This is why the choice of physical cabling has to be primarily determined by three factors. "It is essential that the chosen cabling is viable for about 10 to 12 years. Therefore, the parameters to watch out for are future proofing, available bandwidth, and ease of integration," said Shirish Gariba, VP-IT, Elbee Express Limited.

It is important to consider the bandwidth provided by the physical layer. Most applications today require less than 100 MHz to operate. However, when the focus shifts to bandwidth hoggers such as video traffic, in the range of 125 to 150 MHz of bandwidth is needed. New Ethernet standards like Gigabit Ethernet require the cabling standard to provide a minimum bandwidth of 100 MHz.

Ease of integration and economic feasibility form the final criteria. The cabling must be done in a seamless manner. If it is an upgrade, new cabling must be able to use as much of the existing cable conduits as possible.

A tale of fives

Most deployments still have 100 Mbps switches and Ethernet cards. Hence shifting to full GbE for each desktop is not happening
Rajiv Gerela, GM - Technology, Wipro Spectramind Services Ltd

We need to start the conversation with the status of Cat 5 usage. While it's still very much available, enterprises are no longer going in for this obsolete standard. The bare minimum used in today's organisational LAN is Cat 5e.

A conventional enterprise network (For e.g. ones used in bank branches and small industries) doesn’t host bandwidth hungry applications like video. These needs do not call for more than the 100 MHz maximum provided by Cat 5e. Another situation in which Cat 5e is considered is when the company’s tenancy is going to be only for a short span of time. "Cat 5e is sufficient for smaller offices eg. bank branches. Branch automation does not usually include heavy applications such as video and given the requirement, Cat 5e is cost efficient," said Deepak Jagtiani, National Sales Manager, MPN, Molex India Ltd.

The Box: Cat 5e is good enough is a good case in point to see how LG Electronics fixed on Cat 5e as its cabling technology of choice.

Cat 5e is also the minimum specification required for Gigabit Ethernet. This is yet another reason why enterprises which don't use bandwidth hungry applications prefer to adopt it.

"Cat 5e, meets all the parameters and designs to take care of internal crosstalk. It should suffice to meet the needs of organisations that want to achieve Gigabit transmission," said Vikas Pinjarkar, GM - Sales (SCS), D-Link India Ltd.

However, there are strings attached to Cat 5e's Gigabit Ethernet capabilities. Newer Gigabit standards may operate at frequencies around 125 MHz. The 100 MHz limitation of Cat 5e can put a damper on effective Gigabit Ethernet operation, limiting the standard's future growth potential. This is one of the reasons why most cabling vendors are trying to phase out the standard. "Cat 5e bandwidth is limited to 100 MHz as per EIA/TIA and it is not suitable for Gigabit or any high speed network," said Sujit Singh, Country Manager, Dax Networks.

Of sixes and sevens

Cat 6 cabling is the de facto standard for today's LANs. But for Cat 7, it's still a confused scenario with little adoption. Let's look at Cat 6 first.

The performance specifications and future proof nature of Cat 6 have endeared it to the enterprise. This is the main reason why enterprises are increasingly going in for Cat 6, especially for new installations. "While the standard has largely been Cat 5e till now, organizations have started to move to Cat 6," said Rajiv Gerela, GM - Technology, Wipro Spectramind Services Ltd.

So far, large enterprises have been the biggest adopters of Cat 6. This can be attributed to the fact that Cat 6 is future-proof from an investment standpoint. The available bandwidth of 200 MHz makes it the most attractive option for bandwidth heavy applications like video. Although Cat 5e is sufficient for VoIP, Cat 6 is a better option from the future proofing point of view. "If the application demands the transfer of graphics or video/audio files etc, one should go for Cat 6 rather than for Cat 5e. Cat 6 has definitely shown better results since it has better signal to noise ratio than the Cat 5e," said Vikas Pinjarkar.

Cat 6 is also the best available standard at present for Gigabit Ethernet. It has double the bandwidth of Cat 5e, and improved signal to noise ratio. "The reduced insertion loss (attenuation) of Category 6 cabling (compared to Category 5e) results in the reception of stronger signals. This makes it much easier for the Gigabit Ethernet receiver to identify the voltage level of the signal and correctly interpret the data," said Dileep Kumar, Technical & Product Manager- Enterprise Solutions, Krone.

By offering backward compatibility Cat 6 has won itself many admirers. It is also possible to use existing Cat 5/5e conduits when upgrading to Cat 6 since the two are almost similar in dimensions.

Cat 6 also holds scope for upcoming applications that are on the horizon today. For future specifications like 10 Gigabit Ethernet (10 GbE) over copper, Cat 6 cabling is the bare minimum. "For 10 Gigabit Ethernet applications, Category 5e cabling is not even considered whereas the existing Category 6 cables are expected to support 10GBase-T over a distance of 55 meters," said Dileep Kumar.

See Box: Future-proofing with Cat 6 for an example of how Hughes Software Systems equipped their network with Cat 6.

Now it is time to move on to Cat 7, a technology that has been hyped for the past couple of years. It has remained more hype than reality. "Not much development has been happening on the Cat 7 front due to its STP nature and its requirement for different interfaces. The [existing] instruments are not suitable for testing this standard," said Prasanna Kumar, Sales Director-India & SAARC, Systimax Solutions.

The biggest stumbling block to Cat 7 has been the high cost associated with it. Due to its individually shielded nature, Cat 7 is costlier than UTP cabling even at the procurement stage. Cat 7 also requires non RJ45 connectors that are presently manufactured only by a couple of vendors. The next issue is the bulkier nature of Cat 7 that is once again attributable to its STP form. This gives Cat 7 cabling a larger bend radius and it requires bigger cabling trays. The standard also has problems with grounding. Unless the deployment is on a new site or the organization is willing to completely replace existing cabling by spending a significant amount of money, migration to Cat 7 is just not possible.

With an operating frequency of 600 MHz, Cat 7 is superior to all other standards on the performance specifications front. However, the other issues associated with it have stunted the growth of Cat 7 to a great extent. This has resulted in a scenario where vendors have gone ahead with their own Cat 7 products due to the absence of ratified standards.

It will be at least four years before the standard catches on, if it ever does get over its teething troubles. So it may be wise not to invest in Cat 7 yet.

Gigabit zone

When it comes to the LAN, fibre still takes a backseat. Fibre costs just haven't come down to levels where it is feasible to have fibre deliver gigabit speeds to the desktop. So it is plain Ethernet for the desktop at present, while fibre continues to rule the backbone.

"Even though fibre usage will continue to double annually over the next few years, small distances will continue to be driven by copper. i.e., the desktop will probably continue to be connected using copper irrespective of the interface, 100 Mbps or Gigabit," said Vijay Yadav, Country manager-India and SAARC, 3Com India Pvt Ltd.

Gigabit over Ethernet (GbE) is still not the order of the day. This has more to do with the existing switch architecture and large number of 10/100 Ethernet cards that have been already deployed in organizations than anything else. The shift to infrastructure that supports Gigabit Ethernet is an issue that ought to be sorted out soon. "Most deployments still have 100 Mbps switches and Ethernet cards. As a result shifting to full GbE for each desktop is not going to happen," said Rajiv Gerela.

Other than its lower cost, the advantages that GbE brings to the table are numnerous. GbE is the perfect solution for enterprises wanting to stick to familiar Ethernet technology, because it supports bandwidth hungry applications such as video. The advantage of this approach is that existing technical personnel proficient in Ethernet technology can be retained without retraining as would have been the case with a fibre deployment.

Another advantage that GbE brings is its Power over Ethernet (PoE) capability. This allows network devices to be powered via the switch rather than through separate power outlets. Enhanced uptimes can be achieved as a result.

The distance limitations due to NEXT (near end crosstalk) and ANEXT (alien crosstalk) of GbE have restricted its use in the backbone for large campuses. However, GbE in the LAN is a reality that ought to be seen in many a LAN by end 2005. Technologies that promise to get rid of such issues are on the cards.

On The physical layer’s horizon

Augmented Cat 6 (Cat 6a) is the latest buzzword doing the rounds in cabling. This standard attempts to beef up Cat 6 to make it suitable for 10 Gigabit Ethernet (10 GbE) utilisation.

10 Gigabit over Ethernet (10GBase-T) is a technology that holds the promise of delivering multiple gigabit speeds to the enterprise with the cost benefits of copper. While 10 Gigabit transmission over fibre (802.3ae) is already a reality, its associated costs are prohibitive in nature. This is why the proposed 802.3an standard will deal with 10 Gbps Ethernet over copper.

While Cat 6 and Cat 7 can be utilised to achieve 10 Gigabit transmission over copper, distance limitations are great problems. "At present, 802.3an has been able to achieve 10 Gbps speeds over 70 metres on Cat 6 and 100 meters on Cat 7," said Deepak Jagtiani.

Since Cat 7 is as good as not being there, augmented Cat 6 cabling is expected to fill the void. This is already available, although from only one vendor. The product is out and is expected to support the final draft of 802.3an. The 802.3an standard is expected to be finalised by June 2006. Don't expect it to reach the desktop in the next two years, though!

With inputs from Abhinav Singh.

Anil Patrick R can be reached at: anipatrick@networkmagazineindia.com