How to Configure Inter VLAN Routing on Layer 3 Switches?

With the development of technology, no matter how far you are away from families, you can communicate with them at any time in any places. The same is true to the optic communication, regardless of the physical locations of two hosts or the different VLANs they belong to, they can exchange with each other by inter VLAN routing. Then what is inter VLAN routing and how to configure inter VLAN routing on layer 3 switches?

What Is Inter VLAN Routing?

In figure 1, three computers connected to a gigabit Ethernet switch form a LAN (local area network) within a limited area. However, they cannot communicate with hosts in another LAN, because there is no connection between these Ethernet switches. Then there comes the VLAN which provides us with logical separation or segmentation of our networks to facilitate communication among hosts in different LANs. However, each VLAN is a unique broadcast domain, so computers on separate VLANs are unable to communicate with each other by default. There is a way to solve the problem, and that’s what we are going to shed light on—inter VLAN routing.

LAN and VLAN in NetworkingFig. 1 LAN and VLAN in Networking

The process of forwarding network traffic from one VLAN to another VLAN using routing is known as inter-VLAN routing. One of the ways to carry out inter-VLAN routing is by connecting a router to the switch infrastructure. When using a router to facilitate inter-VLAN routing, the router interfaces can be connected to separate VLANs. Devices on those VLANs communicate with each other via the router. Apart from that, a more convenient way is introduced—configure inter VLAN routing on layer 3 switches. Layer 3 switching is more scalable than a router which only provides a limited number of available ports.

How to Configure Inter VLAN Routing on Layer 3 Switches?

To enable a layer 3 switch to perform routing functions, the switch must have IP routing enabled. 10gb Ethernet switch and 40gb Ethernet switch are recommended for working as layer 3 switch.

Inter VLAN Routing

Fig.2 Inter VLAN Routing on Layer 3 Switches

In figure 2, layer 3 switch is configured with IP address 10.0.0.1. VLAN10 and VLAN20, with IP address 10.10.10.10 and IP address 10.20.20.20 respectively are configured on layer 2 switches. These two IP addresses will be the default gateway addresses for hosts belonging to VLAN10 and VLAN20 on the layer 2 switches respectively. Also, all interfaces connecting the three switches must be configured as trunk ports to allow VLAN10 and VLAN20 tagged frames to pass between switches. Traffic between VLAN10 and VLAN20 will be routed by the layer 3 switch after configuring inter VLAN routing. These steps can be achieved by VLAN configuration command below.

Create VLANs 10 and 20 in the switch database

inter VLAN routing configuration 1
Assign port Fe0/1 in VLAN 10 and port Fe0/2 in VLAN 20

inter VLAN routing configuration 2

Create trunk port Fe0/24

inter VLAN routing configuration 3

Enable layer 3 routing and create VLANs 10 and 20 in the switch database

inter VLAN routing configuration 4

Create trunk ports Fe0/47 Fe0/46

inter VLAN routing configuration 5

Configure Switch VLAN Interfaces (SVI) to acts as a virtual layer 3 interface on the layer 3 switch

inter VLAN routing configuration 6

Conclusion

VLAN is created to enable the communication among hosts in different LANs. Inter VLAN routing is developed to realize the exchange among hosts in different VLANs. Inter VLAN routing on layer 3 switch without a router is also approachable with the development of technology. For more configuration about network switches, please refer to our website www.fs.com.

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.

layer 3 switch in networking

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

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.

Layer 3 Switch VS. Router

In the OSI model, we know that traditional network switch operates at Layer 2 while network routers operate at Layer 3. Besides, switches are understood to be forward traffic based on MAC address, while routers perform the forwarding based on IP address. Layer 3 switches have a lot in common with traditional routers: they can also support the same routing protocols, inspect incoming packets and make dynamic routing decisions based on the source and destination addresses inside. For this reason, many networking beginners are puzzled over the definition and purpose of a Layer 3 switch. So what is on earth Layer 3 switch and what is the difference between Layer 3 switch vs. router?

Layer 3 Switch

Layer 3 switch is also called multilayer switch. It is a specialized hardware device used in network routing, which is conceived as a technology to improve network routing performance on large local area networks (LANs) like corporate intranets. A Layer 3 switch is both a switch and a router. So Layer 3 switch is a switch that can route traffic, and a router with multiple Ethernet ports has a switching functionality. It can switch packets by checking both IP addresses and MAC addresses. On this account, Layer 3 switches separates ports into VLANs and perform the routing between them, in addition to supporting routing protocols such as RIP, OSPF and EIGRP.

Layer 3 switch

Layer 3 Switch VS. Router

From the basics of Layer 3 switch, it may seem to perform the same functionality with the router. In fact, they have some key distinction facts. The key differences between Layer 3 switches and routers lay in the hardware technology used to build the unit. The hardware inside a Layer 3 switch merges that of traditional switches and routers, replacing some of a router’s software logic with hardware to offer better performance in some situations. The table below illustrates the differences between Layer 3 switch and router.

Layer 3 Switch VS. Router

Layer 3 Switch vs. Router: Main Differences:
  • Cost – Layer 3 switch is much more cost effective than router for delivering high-speed inter-VLAN routing. High performance router is typically much more expensive than Layer 3 switch.
  • Port density – Layer 3 switch has much higher port count while router has a lower port density than Layer 3 switch.
  • Flexibility – Layer 3 switch allows you to mix and match Layer 2 and Layer 3 switching. It means that you can configure a Layer 3 switch to operate as a normal Layer 2 switch.
  • WAN technologies support – Layer 3 switch is limited to usage over LAN environment where Inter VLAN routing can be performed. However, when it comes to working on WAN and edge technologies, Layer 3 switch lags behind. Router is the front runner in such scenario where WAN technologies such as Frame Relay or ATM need to be fostered.
  • Hardware/Software decision making – The key difference between Layer 3 switch and router lies in the hardware technology used to making forwarding decision. Layer 3 switch uses ASICs for forwarding decisions. Conversely, the router makes forwarding decisions based on hierarchical Layer-3 addresses.
Layer 3 Switch with VLANs

As here is mentioned the VLAN, so let’s talk about it firstly. A VLAN (virtual LAN) is a logical subnetwork that can group together a collection of devices from different physical LANs. VLANs can improve the overall performance of busy networks. So they are often set up for improved traffic management by larger business computer networks. With a VLAN, traffic can be handled more efficiently by network switches.

Each virtual LAN must be entered and port-mapped on the switch. Routing parameters for each VLAN interface must also be specified. Some Layer 3 switches implement DHCP support that can be used to automatically assign IP addresses to devices within a VLAN. Alternatively, an outside DHCP server can be used, or static IP addresses configured separately. The diagram below shows an example of a layer 3 switching routing between VLANs through its two VLAN interfaces.

Layer 3 Switch with VLAN

These switches are most commonly used to support routing between virtual LANs (VLANs). Benefits of Layer 3 switches for VLANs include:

  • Reduction in the amount of broadcast traffic
  • Simplified security management
  • Improved fault isolation
Conclusion

From what we have discussed about Layer 3 switch vs. router, Layer 3 switch may be more preferable in result of its capability of routing and switching. Besides, it can perform as a top of rack device and a distributed core switching layer at the same time. This reduces the L2 complexity of the client access layer, which makes the network more reliable and easier to manage. FS.COM can provide a comprehensive, scalable and secure portfolio of switches for enterprise and service provider networks. There are also a huge stock of compatible fiber optic transceivers and cables. For more details, please visit www.fs.com.

Ethernet Switch: How Much Do You Know It?

Today, all plants are virtually networked via Ethernet. High requirements are placed on the network infrastructure and network components. Ethernet switch is the integral piece of IT infrastructure, capable of receiving, processing and transmitting data between two devices connected by a physical layer. Due to the increasing application of big data analytics and cloud-based services in various end-user segments, data centers are envisaged to fuel the adoption of Ethernet switch. The augmented global demand for data centers is the key driver for the growth of Ethernet switch market. To satisfy the large and ever-increasing market for Ethernet switch, there are many varieties of switches offered different purposes. This article will help you get a deep understanding of the different types of Ethernet switch.

What is an Ethernet Switch?

A Ethernet switch is a tool for connections between the systems and equipment to forward data selectively to one or more connected devices on the same network. These connections are generally created through the use of structured cabling that links both the station side and the device that you are trying to share data with, such as a server or another computer. In this way, Ethernet switch can control the flow of traffic passing through a network, maximizing the network’s efficiency and security. More advanced Ethernet switch, called managed switch, are also capable of providing additional functions, such as network load balancing, address translation or data encryption and decryption.

FS Ethernet switch

How Dose an Ethernet Switch Work?

Ethernet switch links Ethernet devices together by relaying Ethernet frames between the devices connected to the switches. By moving Ethernet frames between the switch ports, a switch links the traffic carried by the individual network connections into a larger Ethernet network. Ethernet switches perform their linking function by bridging Ethernet frames between Ethernet segments. To do this, they copy Ethernet frames from one switch port to another, based on the Media Access Control (MAC) addresses in the Ethernet frames. Ethernet bridging was initially defined in the 802.1D IEEE Standard for Local and Metropolitan Area Networks: Media Access Control (MAC) Bridges. The standardization of bridging operations in switches makes it possible to buy switches from different vendors that will work together when combined in a network design. That’s the result of lots of hard work on the part of the standards engineers to define a set of standards that vendors could agree upon and implement in their switch designs.

diagram of Ethernet switches connections

Different Types of Ethernet Switch

Ethernet switch are broadly categorized into two main categories – modular switches and fixed switches. Modular switches allow you to add expansion modules into the switches as needed, thereby delivering the best flexibility to address changing networks. Fixed switches are switches with a fixed number of ports and are typically not expandable. This category can be broken down even further into unmanaged, lightly managed, and fully managed.

Unmanaged Switch

An unmanaged switch is mostly used in home networks and small companies or businesses, as it is the most cost effective for deployment scenarios that require only basic layer 2 switching and connectivity. The unmanaged switch is not configurable and have all of their programming built in. It is ready to work straight out of the box. And it is the easiest and simplest installation, because of its small cable connections. An unmanaged switch is perfect in this situation since it requires the least amount of investment with regards to both expense and time.

Smart Switch / Lightly Managed Switch

A smart switch is the middle ground between the unmanaged and fully managed switches. These smart switches offer limited customization, but do possess the granular control abilities that a fully managed switch has. In addition, smart switches offer certain levels of management, quality-of-service (QoS), security, but they are lighter in capabilities and less scalable than the managed switches. Smart switches tend to have a management interface that is more simplified than what managed switches offer. They also offer the capability to set up options like Quality of Service (QoS) and VLANs, which can be helpful if your organization has VoIP phones, or if you want to segment your network into work groups. Therefore, smart switches are the cost-effective alternative to managed switches. They are still valid choices for the regular consumer, as they are generally easy to use and you can glean a bit more information off of them on how your network is configured compared to unmanaged switches.

Fully Managed Switch / Enterprise Managed Switch

Managed Layer 2 Switch: A modern managed switch provides all the functionality of an unmanaged switch. In addition, it can control and configure the behavior of the device. This typically introduces the ability to support virtual LANs (VLANs), which is why almost all organizations deploy managed switches versus their cheaper alternatives.

Managed Layer 3 Switch (Multilayer Switch): This type of switch provides a mix of functionality between that of a managed Layer 2 switch and a router. The amount of router function overlap is highly dependent on the switch model. At the highest level, a multilayer switch provides better performance for LAN routing than almost any standard router on the market, because these switches are designed to offload a lot of this functionality to hardware.

data-center-network-architecture

Managed switches are designed to deliver the most comprehensive set of features to provide the best application experience, the highest levels of security, the most precise control and management of the network, and offer the greatest scalability in the fixed configuration category of switches. As a result, they are usually deployed as aggregation/access switches in very large networks or as core switches in relatively smaller networks. Managed switches should support both L2 switching and L3 IP routing, though you’ll find some with only L2 switching support.

Conclusion

The Ethernet switch plays an integral role in most modern Ethernet local area networks (LANs). Mid-to-large sized LANs contain a number of linked managed switches. Small office/home office (SOHO) applications typically use a single unmanaged switch. This article has introduced the different types of switches. Depending on the number of devices you have and the number of people using the network, you have to choose the right kind of switch that fits your space. FS.COM has provided a comprehensive set of Ethernet switches. If you have any requirements, welcome to visit our website for more detailed information.