How to prepare for 802.11ac Wave2 or Cisco multi-gigabit switches (with NBASE-T / 802.3bz technology support)
To date, over 70 billion meters of Ethernet cable infrastructure based on UTP cables of categories 5e and 6 are used in the world. This is 90% of the installed base. This also means that, until recently, such an infrastructure did not support speeds above 1 Gbit / s (1000 BASE-T) - to fully support the 10G BASE-T standard, a cable of category not lower than Cat 6a is required.
For the industry, this was not a problem until technologies began to appear that required the mass use of connections at speeds above 1 Gbit / s. And here the ratification of 802.11ac Wave2 wireless standards became the catalyst for the process - wireless access points that support this standard are able to provide their customers with a bandwidth of 3.8 Gbit / s or 6.5 Gbit / s.
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Connecting such access points to the network infrastructure using Cat 5e and Cat6 cables obviously limits the available bandwidth to 1 Gbit / s and eliminates the capabilities of the new wireless standard. The logical solution would be to use the already existing 10G BASE-T standard, but this, firstly, would require upgrading almost all cable infrastructure, at least to Cat 6a, and, secondly, potentially increasing the cost of 802.11ac Wave2 access points themselves and the network infrastructure to which they connect.
Fig. 1 - The Evolution of 802.11 Wireless Standards
In 2014, the industry began to actively discuss the possibility of using the existing infrastructure based on UTP for speeds of more than 1 Gbit / s and less than 10 Gbit / s. So in October 2014, it was announced about the organization of the NBASE-T alliance, among the founders of which were companies such as Cisco, Intel, Marvell and others. The goal of the alliance was to discuss and prepare for the ratification of the 2.5G BASE-T and 5G BASE-T standards . The cornerstone of the work of the alliance was the compatibility of such standards with the widely used categories Cat 5e and Cat 6. It should be noted that there were other initiative groups in the industry that solved a similar problem, but ultimately it was the result of the NBASE-T work of the alliance that became the basis of the IEEE standard 802.3bz , which described the use of speeds of 2.5 Gbit / s and 5 Gbit / s under the 802.3 standard and was ratified in September 2016 .
Returning to the work of the NBASE-T alliance, it makes sense to figure out how to create technologies that meet the requirements in such a short time. To do this, you must first remember what determines the possible transfer rate within the framework of the Ethernet standard. Key elements here are:
• Frequency channel available for data transmission in the cable and which is determined by the category of UTP cable. So for Cat 5e this channel is 100 MHz, for Cat 6 - 250 MHz, and for Cat 6a - 500 MHz.
• The type of signal coding and error correction scheme (FEC), which actually determine how many bits per second can be transmitted in the 1 Hz available frequency range. For the 1000 BASE-T standard, for example, PAM-5 coding with a TCM error correction scheme is used, which allows 4 bit / s per 1 Hz of available bandwidth to be encoded. And the 10G BASE-T standard, in turn, uses PAM-16 / DSQ-128 coding with an LDPC error correction scheme, which allows transmitting 6.25 bps in 1 Hz.
• Finally, any UTP cable contains several twisted pairs (usually 2 or 4), each of which can be used for independent and parallel data transfer. For example, the standard 1000 BASE-T uses 4 twisted pairs.
Considering the above, the 1000 BASE-T standard requires a frequency channel 62.5 MHz wide, which allows using any cable category 5e or higher for this standard. 10G BASE-T, despite the more efficient coding-modulation technology, requires a frequency channel of 400 MHz, which is achievable only on categories 6a and higher.
Fig. 2 - Supports IEEE 802.3 Ethernet standards with different UTP categories
In the framework of the task set before the NBASE-T alliance, several main conclusions can be made:
• To achieve speeds of 2.5 Gbit / s and 5 Gbit / s in UTP cable categories 5e and 6, it is sufficient to use a more efficient (than 1000 BASE-T) coding scheme and a little more (compared to the same 1000 BASE-T) wide frequency channel.
• Using the already available PAM-16 / DSQ-128 schemes in combination with LDPC, a frequency channel of 100 MHz (4 pairs * 6.25 bps * 100 MHz = 2.5 Gbit / s) is required for transmitting 2.5 Gbit / s, and for 5 Gbit / s - 200 MHz, which is fully consistent with the capabilities of UTP categories 5e and 6, respectively.
• To implement this technology, it is necessary not only software, but also hardware support in the equipment
Back in 2015 - a year before the IEEE 802.3bz standard was ratified - Cisco implemented this technology in its Catalyst 3560-CX, 3850, 4500E series switches , and then in Catalyst 3650 , calling the technology MultiGigabit Ethernet . Following were announced wireless access points of the standard 802.11ac Wave2 series Cisco AP 3800 . These switches and access points, along with the classic Gigabit ports and 10 Gigabit Ethernet ports, have MultiGigabit ports, which, depending on the type of cable and UTP cable, support 1 Gbit / s, 2.5 Gbit / s, 5 Gbit / s and 10 Gbit / s speeds. For convenience, Cisco visually marks MultiGigabit ports with a special blue bar.
Fig. 3 - Cisco MultiGigabit / 802.3bz Technology Portfolio
As already noted, in September 2016, the result of the NBASE-T alliance was successfully transformed into the official IEEE 802.3bz standard. It should be noted that there are minor differences between Cisco MultiGigabit technology and the 802.3bz standard:
• Different types of messages are used for the auto-negotiation process.
• MultiGigabit, in contrast to 802.3bz, has additional capabilities for forcibly changing the port speed in the event of channel disturbances that were absent at the time of initial connection setup. Within 802.3bz, this feature is optional.
To fully comply with the IEEE 802.3bz standard, Cisco has already released or will release in the near future (the exact release date depends on the product) software update for all Cisco MultiGigabit devices.
In addition to the obvious advantages when using MultiGigabit / 802.3bz technology in wireless networks, they have additional capabilities for Cisco customers. MultiGigabit ports can be used not only to connect access points, but also, for example, to expand the bandwidth between switches at the access and distribution level. It is important that all MultiGigabit ports support Power over Ethernet (PoE, PoE + and UPoE) technologies.
Using MultiGigabit Ethernet (IEEE 802.3bz) technology , Cisco customers today qualitatively increase the efficiency of the existing cable infrastructure, get the opportunity to realize all the benefits of new wireless standards and significantly increase the available bandwidth, while maintaining their own investments.
Additional links:
Cisco Catalyst Switches with MultiGigabit / 802.3bz Technology Support
For the industry, this was not a problem until technologies began to appear that required the mass use of connections at speeds above 1 Gbit / s. And here the ratification of 802.11ac Wave2 wireless standards became the catalyst for the process - wireless access points that support this standard are able to provide their customers with a bandwidth of 3.8 Gbit / s or 6.5 Gbit / s.
')
Connecting such access points to the network infrastructure using Cat 5e and Cat6 cables obviously limits the available bandwidth to 1 Gbit / s and eliminates the capabilities of the new wireless standard. The logical solution would be to use the already existing 10G BASE-T standard, but this, firstly, would require upgrading almost all cable infrastructure, at least to Cat 6a, and, secondly, potentially increasing the cost of 802.11ac Wave2 access points themselves and the network infrastructure to which they connect.
Fig. 1 - The Evolution of 802.11 Wireless Standards
In 2014, the industry began to actively discuss the possibility of using the existing infrastructure based on UTP for speeds of more than 1 Gbit / s and less than 10 Gbit / s. So in October 2014, it was announced about the organization of the NBASE-T alliance, among the founders of which were companies such as Cisco, Intel, Marvell and others. The goal of the alliance was to discuss and prepare for the ratification of the 2.5G BASE-T and 5G BASE-T standards . The cornerstone of the work of the alliance was the compatibility of such standards with the widely used categories Cat 5e and Cat 6. It should be noted that there were other initiative groups in the industry that solved a similar problem, but ultimately it was the result of the NBASE-T work of the alliance that became the basis of the IEEE standard 802.3bz , which described the use of speeds of 2.5 Gbit / s and 5 Gbit / s under the 802.3 standard and was ratified in September 2016 .
Returning to the work of the NBASE-T alliance, it makes sense to figure out how to create technologies that meet the requirements in such a short time. To do this, you must first remember what determines the possible transfer rate within the framework of the Ethernet standard. Key elements here are:
• Frequency channel available for data transmission in the cable and which is determined by the category of UTP cable. So for Cat 5e this channel is 100 MHz, for Cat 6 - 250 MHz, and for Cat 6a - 500 MHz.
• The type of signal coding and error correction scheme (FEC), which actually determine how many bits per second can be transmitted in the 1 Hz available frequency range. For the 1000 BASE-T standard, for example, PAM-5 coding with a TCM error correction scheme is used, which allows 4 bit / s per 1 Hz of available bandwidth to be encoded. And the 10G BASE-T standard, in turn, uses PAM-16 / DSQ-128 coding with an LDPC error correction scheme, which allows transmitting 6.25 bps in 1 Hz.
• Finally, any UTP cable contains several twisted pairs (usually 2 or 4), each of which can be used for independent and parallel data transfer. For example, the standard 1000 BASE-T uses 4 twisted pairs.
Considering the above, the 1000 BASE-T standard requires a frequency channel 62.5 MHz wide, which allows using any cable category 5e or higher for this standard. 10G BASE-T, despite the more efficient coding-modulation technology, requires a frequency channel of 400 MHz, which is achievable only on categories 6a and higher.
Fig. 2 - Supports IEEE 802.3 Ethernet standards with different UTP categories
In the framework of the task set before the NBASE-T alliance, several main conclusions can be made:
• To achieve speeds of 2.5 Gbit / s and 5 Gbit / s in UTP cable categories 5e and 6, it is sufficient to use a more efficient (than 1000 BASE-T) coding scheme and a little more (compared to the same 1000 BASE-T) wide frequency channel.
• Using the already available PAM-16 / DSQ-128 schemes in combination with LDPC, a frequency channel of 100 MHz (4 pairs * 6.25 bps * 100 MHz = 2.5 Gbit / s) is required for transmitting 2.5 Gbit / s, and for 5 Gbit / s - 200 MHz, which is fully consistent with the capabilities of UTP categories 5e and 6, respectively.
• To implement this technology, it is necessary not only software, but also hardware support in the equipment
Back in 2015 - a year before the IEEE 802.3bz standard was ratified - Cisco implemented this technology in its Catalyst 3560-CX, 3850, 4500E series switches , and then in Catalyst 3650 , calling the technology MultiGigabit Ethernet . Following were announced wireless access points of the standard 802.11ac Wave2 series Cisco AP 3800 . These switches and access points, along with the classic Gigabit ports and 10 Gigabit Ethernet ports, have MultiGigabit ports, which, depending on the type of cable and UTP cable, support 1 Gbit / s, 2.5 Gbit / s, 5 Gbit / s and 10 Gbit / s speeds. For convenience, Cisco visually marks MultiGigabit ports with a special blue bar.
Fig. 3 - Cisco MultiGigabit / 802.3bz Technology Portfolio
As already noted, in September 2016, the result of the NBASE-T alliance was successfully transformed into the official IEEE 802.3bz standard. It should be noted that there are minor differences between Cisco MultiGigabit technology and the 802.3bz standard:
• Different types of messages are used for the auto-negotiation process.
• MultiGigabit, in contrast to 802.3bz, has additional capabilities for forcibly changing the port speed in the event of channel disturbances that were absent at the time of initial connection setup. Within 802.3bz, this feature is optional.
To fully comply with the IEEE 802.3bz standard, Cisco has already released or will release in the near future (the exact release date depends on the product) software update for all Cisco MultiGigabit devices.
In addition to the obvious advantages when using MultiGigabit / 802.3bz technology in wireless networks, they have additional capabilities for Cisco customers. MultiGigabit ports can be used not only to connect access points, but also, for example, to expand the bandwidth between switches at the access and distribution level. It is important that all MultiGigabit ports support Power over Ethernet (PoE, PoE + and UPoE) technologies.
Using MultiGigabit Ethernet (IEEE 802.3bz) technology , Cisco customers today qualitatively increase the efficiency of the existing cable infrastructure, get the opportunity to realize all the benefits of new wireless standards and significantly increase the available bandwidth, while maintaining their own investments.
Additional links:
Cisco Catalyst Switches with MultiGigabit / 802.3bz Technology Support
Source: https://habr.com/ru/post/319910/
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