10Gb and Beyond
Fiber has been the traditionally the cable of choice when utilizing 10Gb connectivity. They tend to consume less power and are much lower in latency. Physically the cables take up much less room and is much better for cable management.
However, although the fiber cables themselves are inexpensive, the optics that are used on each end are very costly. At the time of this post, which is around mid 2014, vendors are beginning to bring out 10Gb base-T switches. The cost of the switch itself compared to the fiber is about the same. However, when you account for the optics then, the difference becomes night and day. Optics can be priced anywhere between $300 to $700 a piece. A fully loaded 48 port switch would incur anywhere from $14400 to $33600! And this does not account for the optic that is required at the other end of the cable.
There are however, disadvantages in using copper cables. Mainly to do with the distance limitation. During the early days of 10Gb-T, power consumption of asics were an issue. As such they created a lot of heat and thus required large heat sinks. This prevented the switch to house too many of these ports. Fast forward to 2013-2014, the asic engineers seems to have figured out how to lower the power consumption and now we are beginning to see 48 port densities on 1RU switches. The power consumption improvement has greatly come down to under 3W per port, though still 2-3 times more than fiber. Copper cables are still quite a lot bulkier as well as are restricted to 100M. This still is more than enough for most server rooms and inside wiring of buildings. If you need to run longer distances than 100M, fiber is still the cable of choice.
Below I have compiled a table of different fiber and copper cables vs the maximum distance and speed.
Multi-mode Fiber Optic cables
Generally used in inside wiring, for use with longer distances or higher speed connectivity. They can be identified by jacket colors as well as the fine text imprinted on the cable.
| Category | 100 Mb Ethernet 100BASE-FX | 1 Gb (1000 Mb) Ethernet 1000BASE-SX | 10 Gb Ethernet 10GBASE-SR | 40 Gb Ethernet | 100 Gb Ethernet |
|---|---|---|---|---|---|
| OM1 (62.5/125) | up to 2000 meters (FX) | 275 meters (SX) | 33 meters (SR) | Not supported | Not supported |
| OM2 (50/125) | up to 2000 meters (FX) | 550 meters (SX) | 82 meters (SR) | Not supported | Not supported |
| OM3 (50/125) | up to 2000 meters (FX) | 550 meters (SX) | 300 meters (SR) | 100 meters 330 meters QSFP+ eSR4 | 100 meters |
| OM4 (50/125) | up to 2000 meters (FX) | 1000 meters (SX) | 550 meters (SR) | 150 meters 550 meters QSFP+ eSR4 | 150 meters |
Cisco QSFP+ eSR4 BiDi – QSFP-40G-SR-BD
Cisco has a special optic that allows 40G to run over a single OM3/OM4 fiber instead of conventional 40G optics that utilized 4lanes of MPO-12 fiber. This allows reuse of existing 10G fiber deployments that use single LC – LC fiber optic cables. This optic is Cisco proprietary and will only run on Cisco equipment. Maximum link lengths are 100m for OM3 and 150m for OM4
RJ-45 Copper Ethernet cables
Copper cables are usually much cheaper compared to fiber and are often used for shorter distance patch cabling. Cat 1 – 4 are being omitted as they are not commonly deployed nowadays as they do not support 100 Mb Base-T.
| Category | 10/100 Mb Fast Ethernet 100BASE-TX | 1 Gb (1000 Mb) Gigabit Ethernet 1000BASE-T | 10 Gb Ethernet 10GBASE-T |
|---|---|---|---|
| Cat5 | 100 meters | Not Supported | Not Supported |
| Cat5E | 100 meters | 100 meters | Not Supported |
| Cat6 | 100 meters | 100 meters | 55 meters |
| Cat6A | 100 meters | 100 meters | 100 meters |
| Cat7 (Shielded) | 100 meters | 100 meters | 100 meters |
