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Large enterprises and corporate offices are continuously upgrading their data centers to meet ever growing business requirements, 10 Gbps Ethernet has established itself as the ideal foundational technology. It delivers the following benefits to the next-generation data center:
- Increases bandwidth to support new applications and band-width hungry workloads
- Removes bottlenecks to increase density and provides scalable networks
- Supports effective deployment of unified fabric in both FCoE and iSCSI data centers
10 Gbps ethernet is gaining popularity very rapidly. Most of the networks have already migrated from the older 1 Gbps network to 10 Gbps and others are planning to migrate in near future. The main advantages of shifting towards 10 Gbps ethernet is the higher speed and bandwidth which is offered by 10 Gbps networks.
With this rapid growth in the deployment of 10 Gbps networks, the network equipment manufacturers such as Cisco, Juniper and HP etc. have started to develop and promote more and more switches, routers and firewalls which are capable to support 10 Gbps networks. The per port cost of 10 Gbps is also decreasing and it is now becoming within reach of small to medium enterprises as well.
Several interconnect options are available to install 10 Gbps ethernet in a networks. The most commonly used interconnections are:
- Optical Transceivers (X2, SFP+)
- Direct Attach Cables (DAC)
- Active Optical Cables (AOC)
- Fixed Ports (RJ-45)
- Copper Transceivers
All of the above mentioned interconnection methods have their pros and cons, some methods are suited for large-scale deployments and some are suited for smaller networks. Similarly, each of the interconnection methods has a cost-factor associated with it. Other factors that contribute in making a choice for the interconnection method include the physical cabling infrastructure that is currently available.
We will be discussing the above mentioned methods briefly in the below sections.
Optical Transceivers
Optical transceivers such as X2 and SFP+ support 10 Gbps ethernet connections. Optical transceivers are most commonly used interconnection method as most of the 10 Gbps networks are deployed over fiber optic cables. Fiber optic cables eliminate the distance constraints and allow the network to be more scalable and efficient. Optical transceivers that support 10 Gbps ethernet are available in various types. SR (Short Range) and LR (Long Range) being the most commonly used. Equipment manufacturers have started to give the option of 10 Gbps SFP+ ports in their mid to high end equipment. Figure 1 shows SFP+ and X2 transceivers.
Direct Attach Cables
Direct attach cables or DAC are a cost-effective method to provide 10 Gbps connectivity over smaller distances. The direct attach cables use copper cable with pre-fabricated transceivers at both ends. These transceivers can be plugged in to the standard SFP+ ports on the communication equipment. Direct attach cables are available in various lengths such as 1 meter, 3 meters, 5 meters and 7 meters etc. The maximum length of a direct attach cable is typically up to 10 meters. Figure 2 shows a direct attach cable of 3 meters. Direct attach cables are mainly used to connect equipment which are physically located in close proximity such as within the same network cabinet or datacenter. The main advantage of DAC is that they are very cost-effective and provide easy interconnection without the hassle of patch cords or other optical passive equipment.
Active Optical Cables
Active optical cables, often referred to as AOC, are fiber optic cables with embedded transceivers at both ends, these are quite similar to the direct attach cables discussed in the previous section. The major difference being the nature of the interconnecting cable and length of the cable. AOC cables can be longer that the direct attach cables as fiber optic can support 10 Gbps links to much longer distance. Active optical cables can be as long as 100 meters. The main application of the active optical cables is large datacenters and small campus networks where the distances between the two end points are not longer than 100 meters. AOC provides a great opportunity to replace 1 Gbps copper networks with 10 Gbps networks without causing much expenses. Figure 3 shows an active optical cable assembly.
Fixed Ports
Many of the equipment manufacturers offer network equipment with fixed 10 Gbps ethernet ports. Although, these kind of network equipment are not very popular as the unshielded copper cable doesn’t support 10 Gbps to longer distances. The equipment with 10 Gbps fixed ports is used within small datacenters or top-of-the-rack configurations. A fixed port switch can contain 8-48 ports of 10 Gbps RJ-45 copper ports in a 1 RU form-factor. Category 6 or higher cables are required to utilize 10 Gbps connectivity option, the relatively expensive category 7 cable can support 10 Gbps over a 100 meters link. The main advantage of a fixed port is that it is downwards compatible. Most of the 10 Gbps fixed ports also support 1 Gbps ethernet, hence allowing scalability with option to upgrade to 10 Gbps whenever the need arises.
Copper Transceivers
Copper transceivers that support 10 Gbps ethernet are also available, they are also not very commonly used due to the distance constraints of the unshielded twisted pair copper cables. The main advantage of the copper transceivers is the cost effectiveness and ease of installation. It is ideal for those networks where the fiber optic cable infrastructure is not installed and the network is spread over a relatively smaller geographical area. Figure 4 shows a 10 Gbps copper transceiver with RJ-45 port. An unshielded twisted pair copper patch cord can be used to connect two end points with 10 Gbps copper transceiver installed in them. These transceivers can be installed any communication equipment which support SFP+ transceivers.
