Category Archives: Wiki

An Overview on EVPN and LNV

Bombarded with assorted network applications and protocols, the technologies and solutions for network virtualization delivery have been enriched greatly over past years. Among those technologies, VXLAN, also called virtual extensible local area network, is the key network virtualization. It enables layer 2 segments to be extended over an IP core (the underlay). The initial definition of VXLAN (RFC 7348) only relied on a flood-and-learn approach for MAC address learning. Now, a controller or a technology such as EVPN and LNV in Cumulus Linux can be realized. In this post, we are going to make an exploration on those two techniques: LNV and EVPN.

VXLAN

Figure 1: VXLAN

What Is EVPN

EVPN is also named as Ethernet VPN. It is largely considered as a unified control plane solution for the controller-less VXLAN, allowing for building and deploying VXLANs at scale. The EVPN relies on multi-protocol BGP (MP-BGP) to transport both layer 2 MAC and layer 3 IP information at the same time. It enables a separation between the data layer and control plane layer. By having the combined set of MAC and IP information available for forwarding decisions, optimized routing and switching within a network becomes feasible and the need for flooding to do learning gets minimized or even eliminated.

What Is LNV

LNV is the short of lightweight network virtualization. It is a technique for deploying VXLANs without a central controller on bare metal switches. Typically, it’s able to run the VXLAN service and registration daemons on Cumulus Linux itself. The data path between bridge entities is established on the top of a layer 3 fabric by means of a simple service node coupled with traditional MAC address learning.

The Relationship Between EVPN and LNV

From the above wiki of the EVPN and LNV, it’s easy for us to notice these two technologies are both the applications of VXLAN. For LNV, it can be used to deploy VXLAN without an external controller or software suite on the bare-metal layer 2/3 switches running Cumulus Linux network operating system (NOS). As for EVPN, it is a standards-based control plane for VXLAN, which can be used in any usual bare-metal devices, such as network switch and router. Typically, you cannot apply LNV and EVPN at the same time.

Apart from that, the deployments for EVPN and LNV are also different. Here, we make a configuring model for each of them for your better visualization.

EVPN Configuration Case

 

EVPN

Figure 2: EVPN

In the EVPN-VXLAN network segments shown in Figure 2 (Before), hosts A and B need to exchange traffic. When host A sends a packet to host B or vice versa, the packet must traverse the switch A, a VXLAN tunnel, and the switch B. By default, routing traffic between a VXLAN and a Layer 3 logical interface is disabled. If the functionality is disabled, the pure Layer 3 logical interface on the switch A drops Layer 3 traffic from host A and VXLAN-encapsulated traffic from the switch B. To prevent the pure Layer 3 logical interface on the switch A from dropping this traffic, you can reconfigure the pure Layer 3 logical interface as a Layer 2 logical interface, like Figure 2 (After). After that, you need to associate this interface with a dummy VLAN and a dummy VXLAN network identifier (VNI). Then, an Integrated routing and bridging (IRB) interface need to be created, which provides Layer 3 functionality within the dummy VLAN.

LNV Configuration Case

 

LNV

Figure 3: LNV

The two layer 3 switches are regarded as leaf 1 and leaf 2 in the above figure. They are running with Cumulus Linux and have been configured as bridges. Containing physical switch port interfaces, the two bridges connect to the servers as well as the logical VXLAN interface associated with the bridge. After creating a logical VXLAN interface on both leaf switches, the switches become VTEPs (virtual tunnel end points). The IP address associated with this VTEP is most commonly configured as its loopback address. In the image above, the loopback address is 10.2.1.1 for leaf 1 and 10.2.1.2 for leaf 2.

Summary

In this post, we have introduced the two techniques of network virtualization: EVPN and LNV. These two applications of network virtualization delivery share some similarities, but also quite a lot of differences. Being satisfied with the simplicity, agility, and scalability over the network, the EVPN has been a popular choice in the market.

Hyper Converged Infrastructure vs Converged Infrastructure

Hyper converged infrastructure has been talked a lot in recent years and its adoption is skyrocketing in data centers. However, many people are still confused by this term. Converged Infrastructure vs hyper converged infrastructure, what’s the difference between them? This post will introduce it in details.

What’s Hyper Converged Infrastructure

Hyper converged infrastructure is often named HCI. It is introduced in 2012 to describe a fully software-defined IT infrastructure that virtualizes all the elements of conventional hardware-defined systems. In other words, the networking and storage tasks in the hyper converged infrastructure are implemented virtually through software rather than physically in hardware. Generally, hyper converged infrastructure is at least composed of virtualized computing (a Hypervisor), a virtualized SAN (software-defined storage) and virtualized networking (Software-defined networking). It can be utilized as a way to pool together resources so as to maximize the interoperability of on-premises infrastructure.

Hyperconverged Infrastructure

Hyper Converged Infrastructure vs Converged Infrastructure

Hyper converged infrastructure and converged infrastructure are two alternative solutions to replace the traditional IT infrastructure. This part will tell the differences between them to help you choose one over another for your network deployment.

converged infrastructure vs hyper converged infrastructure

Hyper Converged vs Converged Infrastructure Components

Converged infrastructure defines compute, storage, networking and server virtualization—which are the four core components in a data center—as one dense building block. Hyperconverged infrastructure is born from converged infrastructure and the idea of the software-defined data center (SDDC). Besides the data center’s four core components, hyperconverged infrastructure integrates more components such as backup software, snapshot capabilities, data deduplication, inline compression, WAN optimization and so on.

Hyper Converged vs Converged Infrastructure Principle

Hyper converged infrastructure is a software defined approach. It means the infrastructure operations are logically separated from the physical hardware, and all components in a hyper converged infrastructure have to stay together to function correctly. While converged infrastructure is a hardware-focused, building-block approach. Each component in a converged infrastructure is discrete and can be used for its intended purpose. For example, the server can be separated and used as a server, just as the storage can be separated and used as functional storage.

Hyperconverged VS Converged Infrastructure Principle

Hyper Converged vs Converged Infrastructure Cost

Converged infrastructure allows IT to use a single vendor for end-to-end support for all core components instead of the traditional approach where IT might buy storage from one vendor, network from another and compute from another. It also offers a smaller footprint and less cabling, which can reduce the cost of installation and maintenance.

Hyper converged infrastructure allows IT to build, scale and protect your IT infrastructure more affordably and effectively. For example, a 10GbE Access Layer Switch (8*10/100/1000Base-T+8*1GE SFP Combo+12*10GE SFP+) specially for hyper converged infrastructure only costs US$ 1,699. And the software-defined intelligence reduces operational management, providing automated provisioning of compute and storage capacity for dynamic workloads.

Conclusion

It is reported that hyper converged infrastructure will represent over 35 percent of total integrated system market revenue by 2019. This makes it one of the fastest-growing and most valuable technology segments in the industry today. The upfront costs of hyper converged infrastructure may be a little high now, but in the long term it can pay off.

Related Article: FS S5800-8TF12S Switch: Key Choice for Hyper-Converged Infrastructure Solution

Which Tight Buffered Fiber Distribution Cable Fits Your Application?

Optical fibers with fiber counts ranging from 2 to 144 counts or more are usually coated together inside a single strand of fiber optic cable for better protection and cabling. Multi-fiber optic cables are usually required to pass a lot of distribution points. And each individual optical fiber should connect only one specific optical interface via splicing or terminating by connectors. Thus, fiber optic cables used for distribution should be durable and easy to be terminated. Tight buffered fiber distribution cables, which meet these demands, are widely used in today’s indoor and outdoor applications, like data center and FTTH projects. This post will introduce tight buffered fiber distribution cables.

tight buffered fiber cable

The Beauty of 900um Tight Buffered Fibers

Most of tight buffered fiber distribution cables are designed with 900um tight buffered fibers. This is decided by its applications. As the above mentioned, the distribution cable should be durable and easy to be terminated. The following picture shows the difference between 250um bare fiber and 900um tight buffered fiber. They are alike, but the tight buffered fiber has an additional buffer layer. Compared with bare fibers, 900um tight buffered fibers can provide better protection for the fiber cores. 900um tight buffered fibers are easy to be stripped for splicing and termination. In addition, tight buffered fiber cables are usually small in package and flexible during cabling. These are the main reasons why a lot of fiber optic distribution cables use tight buffered design.

250um vs 950um

Choose Tight Buffered Distribution Fiber Cables According to Applications

900nm tight buffered distribution fiber cables also come in a variety of types. Tight buffered distribution fiber cables used for different environments and applications might have different fiber types, outer jackets and cable structures. The following will introduce several tight buffered distribution fiber cables for your reference.

unitized distribution fiber cable
Indoor Tight Buffered Distribution Fiber Cable

Tight buffered distribution fiber cables used for indoor applications are usually used for intra building backbones and routing between telecommunication rooms. Large tight buffered fiber cable with fiber counts more than 36 fibers generally has “sub-unit” (unitized) design (shown in the above). While smaller tight buffered distribution cables, with fiber counts of 6, 12 or 24, usually have “single-jacket” (non-unitized) designs, which are more flexible in cabling and have much smaller packages and cost advantages. The lower count tight buffered distribution fiber cables with color coded 12 fibers and 24 fibers are very popular. The following picture shows a 24-fiber indoor tight buffered distribution fiber cable with single-jacket design.

24-fiber tight buffered fiber cable

During practical use, these 6, 12 or 24-fiber indoor tight buffered distribution fiber cables can be spliced with other fibers or be terminated with fiber optic connectors. And they can be made into multi-fiber optic pigtails or fiber patch cable after terminated with fiber optic connector on one end or two end. The color coded fibers can also ease fiber cabling.

Indoor/Outdoor Armored Tight Buffered Distribtight buffered fiber terminationution Fiber Cable

Although tight buffered distribution fiber cables are usually used for indoor applications, there is still a place for them in outdoor applications after added with a layer of metal armored tube inside the cable. Armored fiber cables are durable, rodent-proof, water proof and can be directly buried underground during installation, which saves a lot of time and money.

Armored tight buffered distribution fiber cable

Here we strongly recommend a low fiber count armored tight buffered distribution fiber cable which can be used for both indoor and outdoor applications (show in the above picture). This low fiber count armored tight buffered cable has a single-jacket design with a steel armored tape inside the cable. It can be used for both backbone cabling and horizontal cabling in indoor environments. And it can also be used for direct buried applications and aerial application in outdoor environments.

FS.COM Same Day Shipping Tight Buffered Distribution Fiber Cables Solution

During the purchasing of fiber optic cables, one of the most important thing is the shipment of fiber cables. Many bulk fiber cables are transmitted via shipping, which might take a long time. Now FS.COM customers in the USA can enjoy same day shipping for tight buffered distribution fiber cables for both indoor and outdoor applications. Details are shown in the following table. Kindly contact sales@fs.com for more details, if you are interested.

Part No. Description
31909 12 Fibers OM3 Plenum, FRP Strength Member, Non-unitized, Tight-Buffered Distribution Indoor Fiber Optical Cable GJPFJV
31922 12 Fibers OM4 Plenum, FRP Strength Member, Non-unitized, Tight-Buffered Distribution Indoor Fiber Optical Cable GJPFJV
31866 24 Fibers OM4 Riser, FRP Strength Member, Non-unitized, Tight-Buffered Distribution Indoor Fiber Optical Cable GJPFJV
51308 24 Fibers OS2, LSZH, Single-Armored Double-Jacket, Tight-Buffered Distribution Waterproof Indoor/Outdoor Cable GJFZY53

Related Article: Tight-Buffered Fiber Distribution Cable for Indoor and Outdoor Use

100G QSFP28 Fiber Optic Modules and Standards

The developing of 100G fiber optic transceiver has experienced a lot of challenges, thus various types of 100G fiber optic transceivers are being invented. Many 100G modules appeared on the market for a while and disappeared soon. Now it seems that 100G QSFP28 module will win the competition. It has the same cabling structure as 40G QSFP+ module and high density feature, which allows network upgrade to 100G with lower cost and less time. This post will introduce several commonly used 100G QSFP28 modules and standards.

100G QSFP28

QSFP28 module uses four lanes for 100G optical signal transmitting like 40G QSFP+. However, each lane of QSFP28 can transmit 25G optical signal. To fit the various requirements in practical applications, IEEE and MSA standards that support different transmission distances and fiber types are being published.

100G QSFP28 SR4 

100G QSFP28 SR4 is a standard published by IEEE. 100G QSFP28 SR4 module uses eight multimode fibers for 100G dual-way transmission over 850nm. It can support a transmission distance up to 70m over OM3 and 100m OM4 with a MTP interface. 12-fiber MTP OM3/OM4 trunk cables are suggested to be used with QSFP-100G-SR4 modules. 100Gbase-SR4 QSFP28 is the most popular QSFP28 module according to research.

100G QSFP28 LR4

100G QSFp28 LR4 is another 100G standards published by IEEE. It focuses on longer transmission distance over single-mode fiber. 100G QSFP28 LR4 has a duplex LC interface and uses WDM technologies to achieve 100G dual-way transmission over four different wavelengths around 1310nm. It can support distances up to 10km.

Although IEEE has defined two 100G standards separately for short and long distances, the requirements of various applications cannot be fully satisfied. For instances, the 100G-QSFP-LR4 module can support 10km, which is too much for a lot of single-mode applications. It would be uneconomical to buy a 10km module for just 1km or 2km application. MSA has published two 100G standards — 100Gbase-PSM4 and 100Gbase-CWDM4, which can help to decrease the cost of 100G deployment.

100G QSFP28 PSM4

100G QSFP28 PSM4  module has a MTP interface working on wavelength of 1310nm for 100G transmission over single-mode fibers. It can support transmission distance up to 500 meters. 100G QSFP28 PSM4 module is much cheaper than 100Gbase-LR4 QSFP28 module. And 500 meter’s transmission distance can cover a wide range of applications.

100G QSFP28 CWDM4

For longer transmission distance, 100G QSFP28 CWDM4 is suggested, which supports a distance up to 2km over single-mode fiber optic cable. 100Gbase-CWDM4 standard is published by MSA, which is a more cost-effective solution for a wide range of applications compared with 100Gbase-LR4. This module uses CWDM technologies to transmit the 100G optical signal via a duplex LC interface over wavelengths near 1310nm.

100G QSFP28 DAC

100G QSFP28 family also includes a series of direct attach cables. There are mainly two types of QSFP28 DAC, which are QSFP28 to QSFP28 DAC and QSFP28 to SFP28 DAC. These QSFP28 DACs are cost-effective solution for 100G transmission less than 5 meters.

100G QSFP28 Module Interface Fiber Type Distance Standards
100Gbase-SR4 QSFP28 MTP Multimode 70m (OM3); 100m (OM4) IEEE
100Gbase-LR4 QSFP28 LC Duplex Single-mode 10km IEEE
100Gbase-PSM4 QSFP28 MTP Single-mode 500km MSA
100Gbase-CWDM4 QSFP28 LC Duplex Single-mode 2km MSA
Conclusion

There are many ways to transmit to 100G network. 100G QSFP28 modules are the suggested methods. Both IEEE and MSA published standards for 100G QSFP28. For short distance transmission over multimode, 100Gbase-SR4 QSFP28 module is suggested. For single-mode applications, 100Gbase-PSM4 supporting 500m, 100Gbase-CWDM4 supporting 2km and 100Gbase-LR4 supporting 10km are available. The above table shows the basic information of these modules for your reference.

Difference Between 100G-QSFP-PSM4, 100G-QSFP-SR4 and 100G-QSFP-LR4

QSFP28 fiber optic transceiver is becoming the preferred solution for 100G network. It has the same outside looking as the 40G QSFP+ transceiver. But it has a 4*25G electrical interfaces which can transmit optical signals up to 100G. The part numbers of the QSFP28 transceivers are usually market as 100G-QSFP-xx. Now there is a wide selection of 100G QSFP28 modules for 100G Ethernet link, including fiber optic transceiver and direct attached cable. Different part numbers of 100G modules are making customers confused. This post will introduce the differences between the three 100G QSFP28 modules: 100G-QSFP-PSM4, 100G-QSFP-SR4 and 100G-QSFP-LR4.

100G QSFP

Transmission Mode

It is known that QSFP28 modules generally use four lanes to transmit 100G with each lane supporting 25G. Thus, the transmission method is just like 40G QSFP+ transceiver. 100G QSFP28 SR4, LR4 and PSM4 all use the 4*25 transmission mode. However, both the QSFP28 SR4 and QSFP28 PSM4 use a 12-fiber MTP interface which achieves dual-way 100G transmission over 8 fibers at the same time. QSFP28 LR4 uses a LC duplex fiber optic interface for 100G transmission on two directions at the same time. QSFP28 LR4 transmit optical signals over four different wavelengths around 1310nm with each wavelength carrying 25G optical signal. The wavelength ranges of the four lanes are as following:

  • 1294.53nm-1296.59nm
  • 1299.02nm-1301.09nm
  • 1303.54nm-1305.63nm
  • 1308.09nm-1310.19nm
Transmission Media and Distances

The three modules can support different transmission distances. 100G-SR4 QSFP28 module works over wavelength of 850nm and is used with 12-fiber MTP OM3 or OM4 multimode fiber cables for short transmission distances up to 100m. 100G-LR4 QSFP28 module is suggested to be used with single-mode fiber. It works over 1310nm wavelengths and can transmit 100G signals up to 2km. 100G-PSM4 QSFP28 is also used with 12-fiber MTP fiber cables but the fiber type is single-mode and the transmission distance is up to 500m.

100G-QSFP-SR4

Cabling Structure

The transmission mode of the fiber optic transceiver plays an important role during fiber cabling. 100G-QSFP-SR4 and 100G-QSFP-LR4 are invented for short distance transmission and long distance transmission separately. However, the have different cabling structure. The former requires a multi-fiber cabling structure based on 12-fiber MMF MTP interfaces. While 100G-QSFP-LR4 just required the traditional two-fiber SMF cabling structure. In this case, the conversion between multimode fiber to single-mode fiber would be complex as they used totally different cabling structure. Thus, 100G-QSFP-PSM4 is invented which runs over single-mode fiber, but uses the same cabling structure as 100G-QSFP-SR4. With 100G-QSFP-PSM4, the conversion between multimode and single-mode would save more without changing the existing fiber cabling structure.

100G QSFP28 Transceiver Data Rate Interface Fiber Type Transmission
Distance
Wavelengths Cabling Structure
100G-QSFP-SR4 4*25G MTP MMF 70m (OM3);
100m (OM4)
850nm 12-Fiber MTP
100G-QSFP-LR4 4*25G LC SMF 2km 1310nm LC Duplex
100G-QSFP-PSM4 4*25G MTP SMF 500m 1310nm 12-Fiber MTP
Conclusion

The above table listed the basic information of the three modules for your referent. 100G-QSFP-SR4 are suitable for short distance transmission over OM3 or OM4 fiber using 12-MTP fiber cabling system. 100G-QSFP-PSM4 also has a 12-fiber MTP interface but it can support a transmission distance up to 500m over SMF. 100G-QSFP-LR4 is suitable for long transmission distance up to 2km over two single-mode fibers.

Related Article: 40G vs 100G: Which One Is Worth the Investment?