Can a Layer 3 Switch be Used as a Router?

With the development of technology, network switch grows not only in speed like the migration from gigabit Ethernet switch, to 10gb switch, 40gb switch and 100gb switch, but also in complexity to acquire more functions and meet complicated conditions. Layer 3 switch is equipped with advanced functions and is sometimes compared with a router by people. What are layer 3 switch and router? Can a layer 3 switch act as a router? This post will focus on this problem.

What Is Layer 3 Switch and How It Works?

The data switch is a layer 2 switching device that dynamically transmits packets according to the physical addresses (MAC addresses) of connected devices. Layer 3 switch, on the basis of the data switch, boasts additional routing decisions by inspecting the IP addresses. Layer 3 switches are thus able to segregate ports into separate virtual LANs (VLANs) and perform the routing between them. Additionally, this switch helps reduce the amount of broadcast traffic, simplify security management, and improve fault isolation.

What Is Router and How It Works?

A router works at layer 3 of the OSI Model (Network). It is a device usually located at gateways where networks meet, to connect various local networks and wide networks. It decides where to send packets by utilizing an IP Routing table. When an IP packet comes in, the router looks up the destination IP in the IP Routing table. If that destination IP is not found in the table, the router will drop the packet. The router can perform NAT to translate the private IP address to public address, which can get you into the Internet. So it is a common network device in household use.

Can a Layer 3 Switch be Used as a Router?

As a layer 3 switch possesses the routing function of a router, can we replace a router with it? Let’ s have a detailed view of their similarities and disparities.

Layer 3 Switch Vs Router: Similarity

Both layer 3 switch and router work at layer 3 of the network. Layer 3 switches technically have a lot in common with traditional routers. Both of them can support the same routing protocols, inspect incoming packets and make dynamic routing decisions based on the source and destination addresses inside. The switches can also be configured to support routing protocols such as RIP, OSPF, and EIGRP.

Layer 3 Switch Vs Router: Disparity

Internally, the hardware inside a layer 3 switch blends that of traditional switches and routers. As for packet forwarding, router transmits packet by a microprocessor-based software routing engine, while the switch performs switching through hardware. After routing the first data flow, the layer 3 switch will generate a mapping table of MAC addresses and IP addresses, so that the same data flow will directly pass through the layer 2 according to this table, thus eliminating network delay and improving the efficiency of packet forwarding. Externally, layer 3 switches do not offer the WAN-type ports as standard routers do, so they lack WAN functionality.

Router requires configurations before deployment due to the inbuilt operating system. On the contrary, the layer 3 switch is usually ready to go when acquired, and configurations are optional as you like.

From a software perspective, layer 3 switches are not capable of the extra services that routers typically provide, such as NAT and NetFlow.

Conclusion

All in all, it is not recommended to replace a router with layer 3 switch, but you can apply them in the same network at the same time. In addition, whether a layer 3 switch can supplant a router relies upon the switch model and what you expect from it. Some layer 3 switches are almost router substitutions, with a full scope of WAN, firewall, VoIP, and so on. However, those switches are costly, and most layer 3 switches just have Ethernet ports. In this way, a dedicated router is cost-effective than a layer 3 switch.

Bend Radius—How It Can Impact Your Cable Performance?

Why should fiber optic cable not be tightly bent? Are fiber optic cable fragile? These issues are what users care about when deploying fiber patch cables. Usually, fiber optic cable is made from two bend sensitive materials: plastic or glass. It is broken easily when kinked or bent too tightly to exceed the minimum bend radius of cable. Then which factor will influence bend radius? How to choose cables according to it? This blog will provide some hints.

Why Bend Radius Is Important?

When you deploy the fiber optic cable, it is inevitable to flex, pull and bend it due to the practical conditions. However, it is the bend radius that determines how much you can bend a cable. It represents as the safe value that can prevent your cable from damaging or degrading its performance. If a cable is bent beyond its allowed radius, it will generate crosstalk or interference in data transmission, or even shorten its life. That’s why it’s important to know the bend radius of the cables, especially the minimum bend radius,which is the smallest allowed radius the cable can be bent around without signal loss or impairment.

Factors Impact Bend Radius of Cable

The bend radius may differ from cables. The fact is the smaller the minimum bend radius, the more flexible the cable. Here list some factors that may affect this radius of cable.

• Outer Jacket Thickness

The thickness of the outer jacket of a fiber patch cable intended for bending will influence the potential minimum curve radius. Generally speaking, if the outer jacket is thick, the fiber patch cable will have a smaller bend radius. This can be translated by the fact that when the cable is bent, the stretching force makes the outer jacket thinner and even broken. Therefore, if the outer jacket is thin itself, the external tension may deform of break the fragile cable.

• Material Ductility

Cables are manufactured by different materials, and this will affect the radius of the bend. Ductility refers to the flexibility of material under tensile stress or stretching force. If you would like to obtain small curve radius, you should choose cables made of highly ductile materials like copper. An alternative such as glass is more brittle than flexible.

• Core Diameter

The large core diameter determines the small bend radius. Simply put, the single mode fiber has a smaller diameter than multimode fiber, and the single mode fiber cable bears less weight or bending than multimode fiber cable. That’s why the bending radius of single mode fiber optic cable is larger than the multimode fiber optic cable.

How to Choose Fiber Optic Cables based on Bend Radius?

Generally, the multimode fiber optic cable is recommended if the bend radius is the only consideration. And another option is BIF fiber cable. BIF means the bend insensitive fiber which enables tight curve radius when cables are bent or twisted. FS adopts it in producing both multimode and single mode fiber cables to endow them much smaller bend radii than ever before. It realizes more convenience in cable management, as well as less signal loss and less cable damaging. Here is a bend radius chart of BIF fiber optic cable.

Fiber Cable Type	Minimum Bend Radius
OM3/OM4 MTP BIF	7.5mm
Single Mode OS2 MTP BIF	10mm
Uniboot OS2 LC BIF	10mm
Uniboot OM3/OM4 LC BIF	7.5mm

Conclusion

To sum up, the bend radius of cables is paramount for fiber patch cable installations. Factors which influence the minimum radius of fiber optic cable include the outer jacket thickness, material ductility and core diameter. To protect the integrity and performance of cable, we shall not bend the cable beyond its allowed radius.

Connect Optical Transceivers of Different Brands, Fibers or Wavelengths

Optical transceivers usually work coordinately on a pair of network switches. As switch is responsible for directing the flow of data, optical transceiver works for transforming light to data or the opposite. Then how do two transceiver modules work with each other? Can I connect two optical transceivers of different brands, fiber types or wavelengths? You can find answers here.

How Do Two Optical Transceiver Talk to Each Other?

It is known to all that the fiber optic transceiver contains a transmitter and a receiver in the same component. These are arranged in parallel so that they can operate independently from each other. When working on two switches in the same network, the transmitter on one optical transceiver takes an electrical input and converts it to an optical output from a laser diode or LED. The light from the transmitter is coupled into the fiber with a connector and is transmitted through the fiber optic cable plant. The light from the end of the fiber is coupled to a receiver on the other transceiver where a detector converts the light into an electrical signal which is then conditioned properly for use by the receiving equipment.

Fig1. How optical transceiver works

Can I Connect Two Optical Transceivers of Different Brands, Fibers or Wavelengths?

When people are under-budgeted or in urgent need of original optical transceivers that are out of stock, they may turn to other or third-party transceivers. But how to make different transceivers work coordinately without link failure? Is it possible to connect two optical transceivers of different brands, fibers or wavelengths?

Optical Transceiver of Different Brands

As is known to all, fiber optic transceivers are manufactured with a lot of standards and protocols. If the SFP types are of the same protocol at each end, for example: both sides with SX, LX or whatever is currently in use, you can build the link between them. Please note that only the identical protocol is far more enough.

If the network switch comes from different vendors and optical transceivers with different protocols, you will get a dead link between network switch and the transceiver, thus the whole network fails. Make sure the transceiver and the switch at both ends are compatible with each other. However, as the transceiver compatibility is introduced to the optic field, many optical transceivers are now produced to be compatible with other brands. FS almost has no transceiver compatibility issues with other brand switches as all the optical transceivers have been tested to ensure its compatibility before shipping.

Optical Transceiver with Different Fiber Types

Common sense says a multimode sfp cannot work well with a single mode sfp, as the single mode fiber features a narrow core, allowing only a single mode of light to propagate while the multimode fiber has a wider core enabling multiple modes of light to propagate.

Well, as the network evolves, it is unavoidable to use single mode devices on the existing multimode fiber cables, which forces the birth of the mode conditioning cable used for single mode to multimode conversion. It is generally a duplex multimode cable that has a small length of single mode fiber at the start of the transmission length. As for optical transceiver with single mode fiber, connect the single mode connector of the cable into the transmit bore of the transceiver, and multimode connectors of the cable into the receive bore of the transceiver with all other connections going as normal.

Fig.2 Optical transceiver works with mode conditioning cable

Optical Transceiver on Different Wavelengths

A given transceiver generally supports a specific wavelength for both transmitting and receiving. It is vital the wavelength of the fiber optic transceivers (850nm, 1310nm, 1550nm) matches on each end, as a 1310nm sfp transceiver will not talk to a 850nm sfp transceiver. Data transmission implies that data is sent from one end to the other. The SFP transceiver on one end converts electrical signals into optical signals. A built-in laser transmits light through the fiber to the other side. Here, an optical diode converts the light back into an electrical signal. To guarantee that the SFP at the other end is capable of doing this, the SFPs at both ends should support the same wavelength.

Fig.3 Different wavelengths of optical transceiver

Conclusion

To make sure your optical transceivers work smoothly with each other, be careful about their protocols, wavelengths and fiber types in case of link failure. FS provides a great range of fiber optic transceivers with no transceiver compatibility problem and transceiver prices are very competitive.