The journey towards NFV has been underway for some time, with a pivotal milestone being the establishment of the NFV Industry Specification Group (ISG) by the European Telecommunications Standards Institute (ETSI). ETSI ISG NFV played a vital role in defining open-source standards for NFV and creating open-source implementations of NFV.

NFV Component Architecture

The foundation of NFV relies on three key components:

1. NFV Infrastructure (NFVI): NFVI encompasses all the software and hardware elements constituting the environment where NFVs operate. When NFVI spans multiple sites, the connecting network is considered an integral part of the NFVI.

2. Virtualized Network Functions (VNF): VNFs are network functions that can be implemented as software and deployed within the NFVI environment. Examples of VNFs include firewalls, software-defined WAN (SD-WAN) solutions, routing capabilities, and Quality of Service (QoS) management.

3. Management, Automation, and Network Orchestration (MANO): NFV MANO orchestrates and manages VNFs within the NFVI. It encompasses functional blocks, data repositories, reference points, and interfaces that facilitate communication while orchestrating and managing both NFVI and VNFs.

Network Functions Virtualization Use Cases

NFV finds application in various use cases, some of which include:

1. Service Chaining: Communication Service Providers (CSPs) can chain and interlink services or applications such as firewalls and SD-WAN network optimization, offering them as on-demand services.

2. Software-Defined Branch and SD-WAN: SD-WAN network optimization and SD-Branch security functionalities can be virtualized as NFVs, enabling their provisioning as fully virtualized services.

3. Network Monitoring and Security: NFV allows the implementation of firewalls, offering fully virtualized network flow monitoring and the application of security policies for traffic routed through the firewall.

NFV vs. SDN

NFV and Software-Defined Networking (SDN) are often viewed as complementary options for shaping the future of networks.

SDN abstracts network infrastructure into application, control plane, and data plane layers, making network control directly programmable. This facilitates automated provisioning and policy-based resource management. For instance, network changes can be made in software, eliminating the need for manual cable rearrangements.

NFV can be considered a use case of SDN, and vice versa. However, it’s entirely feasible to implement VNFs independently of SDN, and conversely.

Benefits of Network Functions Virtualization (NFV)

NFV offers several advantages, including:

1. Cost Reduction: Traditional physical appliances require purchasing, configuration, and consume space, power, and cooling. NFVs run on standard servers, often with significantly lower overhead requirements.

2. Rapid Deployment: NFVs are software-based, enabling swift deployment and easy updates. Compared to physical systems, initial deployment and updates are more time and resource-efficient.

3. Automation Support: As software entities, NFVs can be configured and managed programmatically. This allows organizations to leverage automation for rapid configuration changes or large-scale updates.

4. Enhanced Flexibility: NFVs, being software-based, can dynamically scale up or down by allocating more or fewer resources as needed. This flexibility is not feasible with physical appliances, which require the acquisition of additional units in fixed-size increments.

5. Reduced Vendor Lock-In: Physical security appliances often lead to vendor lock-in due to the complexity and expense of switching platforms. NFVs, capable of running on diverse hardware, empower organizations to choose hardware that aligns best with their specific needs.

Below is a relevant link for a technical article on Network Functions Virtualization (NFV):

ETSI NFV ISG – Official page of the European Telecommunications Standards Institute (ETSI) NFV Industry Specification Group, providing detailed information on NFV standards.

Demystifying SDN and NFV

Software-Defined Networking (SDN) At its core, SDN is a networking architecture that decouples the control plane from the data plane, enabling centralized control, programmability, and automation of network resources. In simpler terms, it allows network administrators to manage network services through abstraction of lower-level functionality.

Network Function Virtualization (NFV) NFV, on the other hand, focuses on virtualizing network services traditionally carried out by dedicated hardware appliances. It involves replacing specialized hardware with software-based virtual network functions (VNFs) running on standard servers and switches. This agility and flexibility are fundamental to NFV’s appeal.

The Power of SDN

1. Centralized Control SDN shifts control from individual network devices to a central controller, allowing for dynamic, policy-driven management. This centralized approach simplifies network configuration and troubleshooting.

2. Flexibility and Programmability With SDN, network policies can be programmed and adjusted on the fly, enabling rapid responses to changing network conditions. This flexibility is especially valuable in cloud computing environments.

3. Traffic Engineering SDN enables intelligent traffic engineering and optimization, ensuring that network resources are efficiently utilized, and critical applications receive the necessary bandwidth.

4. Security SDN enhances security by facilitating fine-grained control over network traffic. Security policies can be implemented and enforced at the network level, reducing vulnerabilities.

The Advantages of NFV

1. Cost-Efficiency NFV reduces the need for expensive, proprietary hardware, resulting in significant cost savings for organizations. It also allows for better resource utilization, as virtualized network functions can run on the same hardware.

2. Scalability NFV makes it easier to scale network functions up or down based on demand. This agility is vital for handling fluctuating workloads.

3. Rapid Deployment VNFs can be provisioned and deployed rapidly, reducing the time it takes to introduce new network services or make changes to existing ones.

4. Improved Service Innovation NFV promotes service innovation by simplifying the introduction of new network services and features without requiring hardware changes.

The Journey Toward Network Transformation

Embracing SDN and NFV isn’t just a technological shift; it’s a paradigm shift in how we think about network infrastructure. It’s a journey toward greater flexibility, efficiency, and innovation.

Challenges and Considerations

1. Integration Integrating SDN and NFV into existing network infrastructures can be complex. Organizations need a clear migration strategy.

2. Security As with any technology, security remains a top concern. Properly securing the SDN and NFV environment is crucial.

3. Skillset Organizations may need to invest in training and development to ensure their IT teams are well-versed in SDN and NFV technologies.

Conclusion: Pioneering a New Era in Networking

Software-Defined Networking (SDN) and Network Function Virtualization (NFV) represent a seismic shift in the networking landscape. They empower organizations to create more agile, efficient, and responsive networks that can adapt to the demands of today’s digital world.

As businesses continue to embrace digital transformation, SDN and NFV are not just technologies but strategic enablers that can propel organizations into the future. With the right strategy and a commitment to innovation, businesses can harness the full potential of SDN and NFV to drive their success in the digital age.

Follow link to learn more on SDNs.

What Exactly Is a Collapsed Core Architecture?

In a conventional three-tier network model, the campus network is structured into three distinct layers, each serving a specific function. The core layer plays a pivotal role in inter-site transport and routing, handling critical server and internet connections. The distribution layer manages the connectivity between the core and access layers, while the access layer grants network access to end users, including devices such as PCs and tablets.

While this three-tier model is indispensable for intricate campuses with diverse needs, it’s worth exploring more streamlined options, especially for smaller or medium-sized campus networks. This is where the “Collapsed Core Architecture” comes into play. In this model, the core and distribution layers are merged into a single entity, simplifying the network design and management process.

Benefits of Collapsed Core Networks

The Collapsed Core Network operates in a manner similar to its three-tier counterpart, but it offers unique advantages tailored to the needs of smaller campuses:

1. Lower CostsBy amalgamating the core and distribution layers, a collapsed core network significantly reduces the hardware requirements, resulting in cost savings. This model provides an opportunity to harness the benefits of the three-tiered architecture without breaking the budget.

2. Simplified Network ProtocolsWith only two layers involved in communication, the network’s protocol complexity is reduced, minimizing potential protocol-related issues.

3. Designed for Small CampusesThe collapsed core model is purpose-built for small and medium-sized campuses, ensuring that they can enjoy the advantages of a three-tiered model without the burden of unnecessary equipment or complexity.

Limitations of Collapsed Core Networks

While collapsed core networks offer compelling benefits, they do come with certain limitations, which are essential to consider:

1. ScalabilityCollapsed core networks have limited scalability, making it challenging to accommodate rapid growth in terms of additional sites, devices, and users. Cisco suggests that a small network supports up to 200 devices, while a medium network caters to up to 1000. Beyond this scope, transitioning to a three-tier model may become necessary.

2. ResiliencyThe streamlined design of collapsed core networks means there is less redundancy to mitigate individual component failures. While the network remains reliable, the reduced redundancy does entail some trade-offs in terms of resiliency.

3. ManageabilityThe lower redundancy can complicate the management process, especially when dealing with faulty components or distribution policy adjustments. Careful consideration and planning are required to minimize network downtime during such scenarios.

Is a Collapsed Core Design Right for You?

For small and medium-sized campuses seeking the robustness of a three-tiered network architecture without the associated budget constraints and technical complexities, a collapsed core network can be an ideal solution. However, campuses with rapid growth expectations should be prepared to transition to the full three-tiered design when necessary, as scalability, resiliency, and manageability are considerations that can’t be ignored.

In conclusion, the choice of network architecture ultimately depends on your specific needs, resources, and growth expectations. A collapsed core network offers an efficient compromise between complexity and cost-effectiveness, making it a viable option for many smaller enterprises in their pursuit of a resilient and scalable network infrastructure.

Some useful links to Cisco’s resources on the subject of network architecture and design, specifically focusing on the Collapsed Core Network and related concepts:

1. Cisco Campus Network Design Guide: Cisco’s comprehensive guide on campus network design, which covers various architectural models, including the Collapsed Core Network.

2. Cisco Enterprise Network Architecture: Explore Cisco’s solutions and insights into enterprise network architecture, including resources on designing scalable and resilient networks.

3. Cisco Networking Academy: Access Cisco’s Networking Academy, a resource-rich platform offering courses and materials on network design, configuration, and troubleshooting.

4. Cisco Design Zone: Cisco’s Design Zone provides practical design and deployment guides for various network scenarios, including those relevant to the Collapsed Core Network.

These links will provide readers with valuable information and insights from Cisco, a leading authority in the field of network architecture and design.

Designing and constructing a two-tier campus network architecture involves creating an efficient and scalable network infrastructure. This approach closely resembles the three-tier hierarchical design and is commonly implemented in medium-sized campus networks. In this article, we will explore the key considerations, best practices, and technical aspects of designing and building a two-tier campus network architecture.

Considerations for Two-Tier Campus Network Design

Before diving into the design and configuration, it’s essential to understand the motivations and requirements for adopting a two-tier campus network architecture:

1. Cost Efficiency One of the primary motivations for adopting a two-tier design is cost savings. By collapsing the core and distribution layers into a single layer, organizations can reduce network infrastructure expenses while maintaining most of the benefits of a three-tier design.

2. Network Size and Growth Two-tier designs are practical for medium-sized campus networks that do not foresee significant growth. It’s essential to assess the network’s expected size and expansion requirements when choosing this architecture.

3. Network Maintenance If your organization has experience with two-tier designs or prefers a simplified network structure that is easy to manage, a collapsed core model can be a suitable choice.

Best Practices Based on Cisco’s Structured Network Design Principles

Cisco emphasizes several structured engineering principles that apply to network design, including:

– Hierarchy Implementing a hierarchical network model simplifies network design by breaking it down into manageable sections.

– Modularity Dividing network functions into modules enhances design flexibility and simplifies maintenance. Common modules include the enterprise campus, services block, data center, and Internet edge.

– Resiliency Networks should remain available under various conditions, including hardware failures and unusual traffic patterns.

– Flexibility Network designs should be adaptable without major hardware replacements.

To meet these design goals, it is crucial to adopt a hierarchical network architecture that allows for growth and flexibility.

Design and Build a Two-Tier Campus Network Architecture

Now, let’s proceed to the configuration of the two-tier campus network architecture. We’ll follow these steps to set up the network:

1. Test Connectivity to the Internet through the ISP Router Before beginning any work, ensure that the ISP Router is functioning correctly, delivering Internet connectivity at the expected speeds.

2. Identify Interfaces on the Firewall Identify the interfaces dedicated to the LAN, DMZ, and WAN networks on the firewall.

3. Configure Interfaces on the Firewall Set up the interfaces on the firewall for each network segment (LAN, DMZ, WAN).

4. Configure Routing Establish routing between the outside and inside networks and set up necessary routes.

5. Configure Access Control Implement access control policies on the firewall using access lists.

6. Configure Network Address Translation (NAT) Set up NAT to translate private addresses to public IPs.

7. Configure DHCP Relay Configure DHCP relay for IP address assignment.

8. Configure Quality of Service (QoS) Implement QoS policies for prioritizing specific traffic types.

9. Configure DNS Set up DNS servers for name resolution.

10. Test and Verify Connectivity Test connectivity from various network segments to ensure proper routing and access control.

For detailed configuration examples and a step-by-step guide, please refer to the article on Design and Build a Two-Tier Campus Network Architecture.

Network Equipment Used

Here is a list of network equipment used in this configuration:

– Cisco ASA ASA5506-x
– SonicWall NSA 220 (configured similarly to Cisco ASA)
– HPE Aruba Core Layer 3 Switch
– HPE Aruba Access Switches (both multiple and single VLAN configurations)

Network Topology

The network topology consists of three key parts:

1. WAN Layer
2. Collapsed Core (Aggregation or Distribution and Core Layer)
3. Access Layer

Each layer serves a specific purpose in the network hierarchy.

Configuration Examples

Below are snippets of configuration commands for different network components. These commands provide a simplified overview of the configuration process for reference:

– Configuring firewall interfaces (Inside, Outside, DMZ).
– Configuring VLANs and SVIs on the core switch.
– Configuring VLANs and interfaces on access switches.
– Configuring routing and routes between network segments.
– Configuring DHCP relay and DNS settings.

Conclusion

Designing and building a two-tier campus network architecture involves careful planning, adherence to best practices, and precise configuration of network components. This architecture offers a cost-effective and scalable solution for medium-sized campuses. Following Cisco’s structured network design principles and best practices ensures a reliable and efficient network infrastructure.

Please note that this article provides an overview of the configuration process, and real-world implementations may require additional considerations and fine-tuning based on specific network requirements and equipment capabilities.

Note: I have used this SKU size as it’s lightweight and sufficient for this lab exercise – Standard B1s (1 vcpu, 1 GiB memory)

First, we’ll create two Linux Ubuntu virtual machines in Azure. We’ll use Azure because it offers a quick and easy way to create virtual machines.

Step 1:

• Sign in to the Azure portal.
• Click on “Create a resource” in the top left corner of the screen.
• Search for “Ubuntu Server” and select the “Ubuntu Server 18.04 LTS” option.
• Choose a subscription, resource group, virtual machine name, region, and size for the virtual machine. You’ll need to create one VM for the image server and another for the video server.
• Set up a username and password for the VM.
• Choose “SSH public key” as the authentication type.
• Create an SSH key pair if you don’t already have one.
• Click “Review + create” to review your settings and create the VM.

Repeat this process to create a second VM for the video server.

Step 2: Configure the Virtual Machines

Next, we’ll configure the virtual machines to serve static assets. We’ll use Nginx as the web server, but you can use any web server you prefer.

SSH into the image server VM or use Azure Run Command Tool.
Install Nginx by running the command

"sudo apt-get update && sudo apt-get install nginx".

Copy your images to the VM and place them in the “/var/www/html” directory.
Repeat this process on the video server VM, but copy your videos to the “/var/www/html/videos” directory.

A step by step walkthrough as per below;
Install Nginx

sudo apt-get -y update
sudo apt-get -y install nginx

Create Images Folder Path

mkdir /var/www/html/images/
echo "<h1> This is the Images Server </h1>" > /var/www/html/images/index.html

Create Videos Folder Path

mkdir /var/www/html/videos/
echo "<h1>This is the Videos Server</h1>" > /var/www/html/videos/index.html

Step 3: Create the Application Gateway

Now, we’ll create the application gateway in Azure. This will enable us to route traffic to the correct VM based on the URL path.

• Sign in to the Azure portal.
• Click on “Create a resource” in the top left corner of the screen.
• Search for “Application Gateway” and select the “Application Gateway v2” option.
• Choose a subscription, resource group, name, region, and SKU for the application gateway.
• Choose the “Backend pools” option in the left menu.
• Click “Add” to add a backend pool.
• Choose the “Virtual machines” option for the backend target type.
• Choose the image server and video server virtual machines as the targets.
• Choose the “HTTP settings” option in the left menu.
• Click “Add” to add an HTTP setting.
• Choose a name for the HTTP setting and configure the protocol, port, and cookie settings.
• Choose the “Rules” option in the left menu.
• Click “Add” to add a rule.
• Choose a name for the rule and configure the listener, backend target, and URL path map settings.
• Test your application gateway by accessing the image and video servers through the gateway URL with the appropriate path.

Create Application Gateway

create application gateway public ip

create application gateway with images backend pool

create application gateway with videos backend pool

create application gateway images backend setting

create application gateway add multiple targets to create path-based rule

create application gateway add multiple images path-based rule

create application gateway videos backend setting

create application gateway add multiple videos path-based rule

create application gateway add backend targets

create application gateway frontend routing rules for backend pools

Browse to Video Server Resource

create application gateway and check health

Check Overview of Application Gateway

Awesome links for further reading;
Apache web server documentation: https://httpd.apache.org/docs/
Azure documentation: https://docs.microsoft.com/en-us/azure/
Ubuntu server documentation: https://ubuntu.com/server/docs
Virtual machines in Azure: https://docs.microsoft.com/en-us/azure/virtual-machines/
Application Gateway in Azure: https://docs.microsoft.com/en-us/azure/application-gateway/

DNAT (Destination NAT) is a type of NAT that allows inbound traffic to be redirected from a public IP address to a private IP address. DNAT is typically used when a server on a private network needs to be accessed from the internet. When a request is made to the public IP address, the NAT device will translate the public IP address to the private IP address of the server and forward the request to the server.

Use cases for DNAT:

Remote access: DNAT can be used to enable remote access to a server on a private network. For example, a company might use DNAT to allow employees to access a company server from home or when traveling.
Load balancing: DNAT can be used to distribute inbound traffic across multiple servers on a private network. This can help improve performance and ensure that traffic is handled efficiently.
Website hosting: DNAT can be used to host a website on a private network. When a request is made to the public IP address of the website, the DNAT device will redirect the traffic to the private IP address of the web server.

On the other hand, SNAT (Source NAT) is a type of NAT that changes the source IP address of outbound traffic. SNAT is typically used when multiple devices on a private network need to access the internet using a single public IP address. When a device on the private network sends a request to the internet, the NAT device will translate the private IP address to the public IP address before forwarding the request to the internet.

Use cases for SNAT:

Internet sharing: SNAT can be used to enable multiple devices on a private network to share a single public IP address. This is common in home networks where multiple devices (such as smartphones, tablets, and laptops) need to access the internet.
Security: SNAT can be used to hide the IP addresses of devices on a private network from the internet. This can help improve security by making it harder for attackers to target individual devices on the network.
Compliance: SNAT can be used to comply with certain regulations that require all outgoing traffic to have the same source IP address. For example, some financial institutions might use SNAT to comply with regulations that require all outgoing traffic to originate from a specific IP address.

Now that you have understood the differences between SNAT and DNAT, why don’t we go through a set of commands we can use to achieve this on Cisco equipment?

SNAT (Source NAT) and DNAT (Destination NAT) are two commonly used features in Cisco networking to manipulate network traffic. Here are the commands for configuring SNAT and DNAT in Cisco devices:

SNAT:

To configure SNAT on a Cisco router or firewall, use the following command:

ip nat inside source static  

This command tells the router/firewall to translate the source IP address of traffic leaving the “inside” interface to the specified “public” IP address.

DNAT:

To configure DNAT on a Cisco router or firewall, use the following command:

ip nat outside source static  

This command tells the router/firewall to translate the destination IP address of traffic arriving at the “outside” interface to the specified “local” IP address.

Note: The above commands are just examples, and the actual syntax may vary depending on the specific device and operating system version.

In summary, DNAT is used to translate inbound traffic to a private IP address, while SNAT is used to translate outbound traffic to a public IP address. Both DNAT and SNAT are useful techniques for managing IP addresses in a network and ensuring that devices on a private network can access the internet using a single public IP address.

I have another article demonstrating the real use case of NAT here – https://www.expertnetworkconsultant.com/configuring/how-to-configure-nat-the-cisco-and-vyos-way/

Here are some links to Cisco’s website that explain how to configure SNAT and DNAT:

SNAT:

Configuring Network Address Translation: https://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/26704-nat-faq-00.html

Configuring Static NAT: https://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/26704-nat-faq-00.html#anc13

DNAT:

Configuring Port Address Translation: https://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/26704-nat-faq-00.html#anc11

Configuring Dynamic NAT: https://www.cisco.com/c/en/us/support/docs/ip/network-address-translation-nat/26704-nat-faq-00.html#anc12

These links provide detailed information on the configuration of SNAT and DNAT, along with examples and best practices.

What is Routing Security?

Routing security refers to the measures taken to protect the routing infrastructure of a network from attacks or other forms of unauthorized access. This includes securing routers, switches, and other network devices that are involved in directing traffic. The goal of routing security is to ensure that traffic is routed correctly and securely, without interference or interception by unauthorized parties.

Why is Routing Security Important?

Routing security is critical to maintaining the integrity and availability of the network. A compromised routing infrastructure can result in the following:

Loss of Confidentiality: Attackers can intercept sensitive data by redirecting traffic to a malicious endpoint.
Loss of Integrity: Attackers can modify or tamper with data packets, potentially compromising the data’s authenticity and reliability.

Loss of Availability: Attackers can disrupt network traffic by blocking or redirecting packets, causing downtime for critical services.

Best Practices for Securing a Network’s Routing Infrastructure
There are several best practices that network administrators can follow to secure their routing infrastructure. These include:

Implement Access Control Lists (ACLs)
ACLs are a set of rules that determine which traffic is allowed or denied access to a network. They can be used to block traffic from specific IP addresses, protocols, or ports, and can be applied at different levels of the network. For example, an ACL can be applied to a router to block traffic from a specific IP address or port, or it can be applied to a switch to block traffic from a particular VLAN.
Here is a sample Cisco ACL configuration:

Router(config)# access-list 100 deny ip 10.0.0.0 0.255.255.255 any
Router(config)# access-list 100 permit ip any any
Router(config)# interface fa0/0
Router(config-if)# ip access-group 100 in

This configuration creates an ACL that denies traffic from any IP address in the 10.0.0.0/8 network and permits all other traffic. The ACL is then applied to the inbound interface of the router’s Fa0/0 interface.

Use Routing Protocols with Authentication
Routing protocols are used to exchange routing information between routers and switches. However, these protocols can be vulnerable to attacks that attempt to manipulate the routing tables. To prevent this, it is recommended to use routing protocols that support authentication, such as OSPFv3 or BGP. Authentication ensures that only authorized devices can participate in the routing process.

Here is a sample Cisco OSPFv3 configuration:

Router(config)# interface fa0/0
Router(config-if)# ipv6 ospf authentication message-digest
Router(config-if)# ipv6 ospf message-digest-key 1 md5 cisco123
Router(config)# ipv6 router ospf 1
Router(config-rtr)# area 0 authentication message-digest

This configuration enables OSPFv3 authentication using MD5 encryption with the key “cisco123”. It also enables authentication for the router’s OSPFv3 area.

Use Secure Management Practices
Network devices must be securely managed to prevent unauthorized access or modifications. This includes setting strong passwords for user accounts, disabling unnecessary services, and limiting access to management interfaces.

Here is a sample Cisco configuration to enable secure management:

Router(config)# enable secret cisco123
Router(config)# line vty 0 4
Router(config-line)# login
Router(config-line)# transport input ssh
Router(config)# ip ssh version 2

This configuration sets the enable secret to “cisco123”, requiring a password to access privileged mode. It also configures the virtual terminal lines for SSH access only and enables SSH version 2 for secure remote access.

Implement Network Segmentation
Network segmentation involves dividing the network into smaller, isolated segments, each with its own security controls. This reduces the attack surface and limits the impact of a potential breach. For example, critical servers and services can be placed in a separate segment that is only accessible to authorized personnel. Here is a sample Cisco configuration for VLAN segmentation:

Switch(config)# vlan 10
Switch(config-vlan)# name Finance
Switch(config-vlan)# exit

Switch(config)# vlan 20
Switch(config-vlan)# name HR
Switch(config-vlan)# exit

Switch(config)# interface fa0/1
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 10
Switch(config-if)# exit

Switch(config)# interface fa0/2
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 20
Switch(config-if)# exit

This configuration creates two VLANs for Finance and HR, respectively. The switch’s Fa0/1 interface is assigned to the Finance VLAN, and the Fa0/2 interface is assigned to the HR VLAN. This creates a logical separation between the two segments, limiting communication between them.

Keep Software Up-to-Date
Keeping network device software up-to-date is critical to address security vulnerabilities and bugs. Regularly check for firmware and software updates from the vendor and apply them as soon as possible. Here is a sample Cisco configuration to upgrade the IOS image:

Router# copy tftp://192.168.1.10/c2960x-universalk9-mz.152-4.E6.bin flash:
Router# configure terminal
Router(config)# boot system flash:/c2960x-universalk9-mz.152-4.E6.bin
Router(config)# exit
Router# reload

This configuration copies the new IOS image from a TFTP server with the IP address of 192.168.1.10 and saves it to the device’s flash memory. It then sets the new IOS image as the default boot image and reloads the device to apply the update.

Conclusion

Routing security is critical to maintaining the integrity and availability of a network’s infrastructure. Following best practices, such as implementing access control lists, using routing protocols with authentication, implementing network segmentation, and keeping software up-to-date, can help mitigate the risks of attacks and unauthorized access. Cisco devices provide many security features and configurations to help secure a network’s routing infrastructure, and these code samples are just a few examples of how to do so. It is crucial to continuously monitor and update the network’s security to stay ahead of potential threats.

This article How to Connect GNS3 to a Physical Network is a no nonsense step by step guide to setting up a full hands on GNS3 lab for the serious network engineer or student. This How to Connect GNS3 to a Physical Network lab is what it says on the tin. Routing, Switching, Firewall Security, Infrastructure, Virtualisation and Internet all made possible by this advanced lab created by some of the smartest network engineers of today.

How to Connect GNS3 to a Physical Network | Connecting Switch Uplink Interfaces (Introduction)

Trust me, we understand your frustration. You really want a handson lab but GNS3 has some gotcha’s, and it’s no longer economically efficient to have a lot of kit so what do you do? Thank God, we have the answer in the steps below. It will cost you next to nothing but guaranteed to give you the full blown hands-on experience without any compromises.

You will be able to create a myriad of labs, change network topologies without much effort and extra configuration. This lab is suitable for a business, university or individuals. It’s vendor agnostic and so can support your Next-Generation ASA Firewall, Sonic Wall, Juniper, Palo Alto, HP Aruba Switch, Cisco Catalyst Switches, Windows Servers and to make it even more interesting, if it has an interface, you can lab it.

The advantage here is that you can practice full switching and routing protocols like HSRP | GLBP | VRRP, STP, OSPF, EIGRP to name but a few.

Let us put together our kit list (Some of these you may already have at your disposal)

Hardware Kit

• 1 x Desktop Computer or Workstation with Expansion Slots (If you own a laptop, you will need USB C to Ethernet Adapters) – Not truly reliable hence the workstation preference.
• 2 x 4 Port PCI-E 1Gbps Network Interface Card | 2 Access Buildings
• 2 x Access Switches | Cisco Catalyst Switches or HPE Aruba Switches | Vendor Agnostic

Software and Operating System

• Microsoft Windows
• Linux Ubuntu
• GNS3 Application

Figure 1.0 – Connect Network Device to Ethernet Adapter

Figure 1.1 – 4 Port Ethernet Adapter

Figure 1.2 – Connect Switch Uplink Interfaces

Interface 47 and 48 are our respective uplinks to Core Routers R1 and R2 respectively. To make the interface layer 3 or routed, the following configuration converts them to routed interfaces.

Example of Configuration

switch(config)# interface Fa0/47 
switch(config-if)# no switchport 
switch(config-if)# 

switch(config)# interface Fa0/48
switch(config-if)# no switchport 
switch(config-if)# 

Figure 1.3 – Uplinks of Switches 1 and 2

Access Switch 1

switch(config)# interface 47 
switch(config-if)# untagged vlan 1008
switch(config-if)# ip address 172.16.254.10

switch(config)# interface 48
switch(config-if)# untagged vlan 1012
switch(config-if)# ip address 172.16.254.14

Access Switch 2

switch(config)# interface 47 
switch(config-if)# untagged vlan 1016
switch(config-if)# ip address 172.16.254.18

switch(config)# interface 48
switch(config-if)# untagged vlan 1020
switch(config-if)# ip address 172.16.254.22

Figure 1.4 – Switches Uplinks at back of Desktop connected to Physical Interfaces

Step 1 – Connect Ethernet Interfaces to Desktop Network Adapters

How to Connect GNS3 to a Physical Network | Configuring Physical Network Interfaces (Part 1)

Identify Interfaces on your computer

Command: nmcli dev status

# nmcli dev status
DEVICE  TYPE      STATE         CONNECTION
eth1    ethernet  connected     eth1
eth0    ethernet  connected     eth0
eth2    ethernet  disconnected  --
lo      loopback  unmanaged     --

Command: ifconfig

eno1: flags=4099  mtu 1500
        ether 40:a8:f0:49:7b:0a  txqueuelen 1000  (Ethernet)
        RX packets 0  bytes 0 (0.0 B)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 0  bytes 0 (0.0 B)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0
        device interrupt 20  memory 0xf7c00000-f7c20000  

lo: flags=73  mtu 65536
        inet 127.0.0.1  netmask 255.0.0.0
        inet6 ::1  prefixlen 128  scopeid 0x10
        loop  txqueuelen 1000  (Local Loopback)
        RX packets 24697  bytes 24138502 (24.1 MB)
        RX errors 0  dropped 0  overruns 0  frame 0
        TX packets 24697  bytes 24138502 (24.1 MB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

Step 2 – Configure IP Addresses for Uplink Interfaces

How to Connect GNS3 to a Physical Network | Configuring IP Addresses for Network Interfaces (Part 2)

Step 3 – Connect Uplinks to Core Routers

How to Connect GNS3 to a Physical Network | Connecting Switch Uplinks to Core Routers (Part 3)

Step 4 – Test Connectivity with Pings

How to Connect GNS3 to a Physical Network | Test Connectivity with ICMP Pings (Part 4)

Download the full lab here: Connecting GNS3 to Physical Network – Multilayer Network Access Design

Related Post:How to Connect GNS3 to Internet

Routing works by using a routing table, which is a database of network routes. This table contains information about the various networks and their connections. When a data packet arrives at a router, the router looks up the destination address in its routing table and determines the best path for the packet to take based on the information in the table. The router then forwards the packet to the next router or network along the chosen path until it reaches its final destination.

What are the different types of routing protocols and how do they differ from each other?
There are two main types of routing protocols: distance-vector protocols and link-state protocols.

Distance-vector protocols, such as Routing Information Protocol (RIP) and Interior Gateway Routing Protocol (IGRP), use the number of hops to a destination as the metric for determining the best path. These protocols periodically send updates to neighboring routers to inform them of the routes they know about.

Link-state protocols, such as Open Shortest Path First (OSPF) and Intermediate System to Intermediate System (IS-IS), use more complex metrics to determine the best path, taking into account factors such as bandwidth, delay, and reliability. These protocols exchange detailed information about the network topology to build a complete picture of the network, allowing them to make more informed routing decisions.

What is the difference between static routing and dynamic routing?
Static routing is a type of routing where the network administrator manually configures the routes in the routing table. This is often used in small networks where the topology is simple and changes are infrequent.

Dynamic routing, on the other hand, is a type of routing where routers automatically exchange information about the network topology and use this information to update their routing tables. This is typically used in larger networks where the topology is more complex and changes are more frequent.

Dynamic routing protocols can adapt to changes in the network, such as the addition or removal of a router or a link failure, by recalculating the best path based on the current network conditions. This makes dynamic routing more efficient and reliable than static routing in larger, more complex networks.

What is a routing table and how is it used in routing?
A routing table is a database of network routes that is used by routers to determine the best path for network traffic. Each entry in the routing table contains information about a particular network, including the network address, the next-hop router, and the metric or cost associated with that route.

When a router receives a packet, it looks up the destination address in its routing table and chooses the best route based on the information in the table. The router then forwards the packet to the next router along the chosen path until it reaches its final destination.

How are routes added to the routing table?
Routes can be added to the routing table in several ways, including:

Manual configuration: In static routing, routes are added manually by the network administrator. This involves specifying the destination network and the next-hop router to reach that network.

Dynamic routing protocols: In dynamic routing, routes are automatically added to the routing table by the routing protocol. The routing protocol exchanges information about the network topology with neighboring routers and uses this information to calculate the best path to each destination network.

Default routes: A default route is a route that is used when there is no specific route in the routing table for a given destination. A default route can be manually configured or learned dynamically through a routing protocol.

It’s important to note that routing tables are not static and can change over time. Routes can be added, removed, or modified as network conditions change. This ensures that routers are always using the most up-to-date information to make routing decisions.

What is a default gateway and how is it used in routing?

In computer networking, a default gateway is a device or node that serves as an access point for network devices to communicate outside of their own network. The default gateway acts as a “traffic cop” for network traffic, directing it between different networks or subnets.

When a device on a network wants to communicate with another device on a different network or subnet, it sends the data packet to the default gateway. The default gateway then forwards the packet to the destination network or subnet, based on the routing information in its routing table.

The default gateway is typically a router or a switch with routing capabilities. It is configured with an IP address that is on the same network as the devices it serves. When a device sends data packets to the default gateway, the gateway checks the destination IP address and forwards the packets to the appropriate network.

In some cases, the default gateway may be set to a “null” or “black hole” address, which effectively drops any data packets that are sent to it. This can be useful for testing or troubleshooting purposes.

What is a routing loop and how can it be prevented?

Routing loops are a common problem in computer networking that can cause data packets to circulate indefinitely, leading to network congestion and potentially bringing down the network. A routing loop occurs when a packet is forwarded in a loop between two or more routers that incorrectly believe that they have the shortest path to the destination.

The cause of a routing loop can be attributed to many factors, such as incorrect or incomplete routing information, and network topology changes that were not propagated correctly. When a routing loop occurs, it can cause packets to bounce back and forth between routers, creating congestion and significantly degrading network performance.

To prevent routing loops, network administrators can implement various techniques such as:

Implementing proper network design: Proper network design can ensure that loops are not created, and routing protocols are configured correctly.

Enabling loop prevention mechanisms: Some routing protocols such as OSPF and IS-IS have built-in mechanisms to prevent routing loops, such as route poisoning, split horizon, and hold-down timers.

Implementing reliable link-state advertisements (LSAs): By ensuring that LSAs are reliable and accurate, routing information can be propagated quickly and correctly, reducing the chances of a routing loop.

Regularly checking the network for anomalies: Network administrators should regularly monitor the network for anomalies, such as high packet loss, which can indicate the presence of a routing loop.

Routing loops are a common problem that can cause significant network performance degradation. By implementing proper network design, enabling loop prevention mechanisms, implementing reliable LSAs, and regularly checking the network for anomalies, network administrators can reduce the likelihood of routing loops and ensure the efficient and reliable operation of the network.

Routing protocols are essential for the proper functioning of computer networks, as they ensure that data packets are delivered efficiently and accurately to their intended destinations. Routing protocol convergence is a critical concept in network engineering, referring to the process by which routers in a network agree on the best path for forwarding data packets.

Routing protocol convergence occurs when all routers in a network have updated their routing tables to reflect the latest network topology changes. This can happen after a link or router failure, a new router or link addition, or other changes to the network configuration. During the convergence process, routers communicate with one another to update their routing tables and ensure that all routers are using the same information to make routing decisions.

The importance of routing protocol convergence lies in the fact that it ensures that all routers in a network are using the same routing information. This helps to prevent routing loops, where data packets are forwarded in a circular fashion between routers and never reach their destination. Routing loops can cause network congestion, delays, and even complete network failure if not addressed promptly.

In addition to preventing routing loops, routing protocol convergence also helps to improve network performance and reliability. When routers are using consistent routing information, data packets can be forwarded quickly and efficiently along the optimal path, reducing delays and improving network throughput.

Quality of Service (QoS) is a networking concept that refers to the ability to prioritize and manage network traffic to ensure that critical applications receive the necessary resources and bandwidth they need to function properly. QoS is particularly important in today’s networks, where a wide variety of applications, services, and devices compete for limited network resources.

Implementing QoS in routing involves several techniques that are designed to manage and control network traffic. One of the most common techniques is traffic shaping, which involves regulating the flow of traffic to prevent network congestion and ensure that critical applications receive the bandwidth they need to function properly. This is achieved by setting policies that prioritize traffic based on application type, destination, or user.

Another QoS technique used in routing is bandwidth reservation, which involves reserving a certain amount of network bandwidth for specific applications or users. This helps ensure that critical applications always have the resources they need to function optimally, even during periods of high network traffic.

Other QoS techniques used in routing include packet classification, queuing, and scheduling, which are all designed to manage and control network traffic and ensure that critical applications receive the necessary resources and bandwidth they need.

The benefits of implementing QoS in routing are numerous. For one, QoS helps ensure that critical applications, such as voice and video, receive the necessary resources and bandwidth they need to function properly. This helps prevent issues such as jitter, latency, and dropped packets that can lead to poor call quality and user frustration.

Additionally, QoS helps improve overall network performance and reliability by preventing network congestion and ensuring that critical applications always have the resources they need. This helps minimize downtime and maximizes productivity, which can lead to significant cost savings for businesses and organizations.

In summary, implementing QoS in routing is essential for managing and controlling network traffic in today’s complex networks. By using traffic shaping, bandwidth reservation, and other QoS techniques, network administrators can ensure that critical applications receive the necessary resources and bandwidth they need to function properly, leading to improved network performance, reliability, and user satisfaction.

Routing protocol convergence is a critical process for the proper functioning of computer networks. It ensures that all routers in a network are using the same routing information and prevents routing loops, helping to improve network performance and reliability. Network engineers must understand the importance of routing protocol convergence and take steps to ensure that their networks are properly configured and maintained to avoid routing issues.

Conclusion:
Routing is a critical component of modern networking, enabling data to be efficiently and accurately delivered across complex networks. Routing protocols, such as distance-vector and link-state protocols, play a key role in determining the best path for network traffic. Static routing and dynamic routing offer different approaches to configuring network routes, with dynamic routing offering greater flexibility and adaptability. The routing table is a vital tool used by routers to make routing decisions, containing information about the various networks and their connections. By understanding how routing works and the different types of routing protocols available, network administrators can design and maintain networks that are efficient, reliable, and secure.

Routers:

Routers are the backbone of any enterprise network. They are responsible for forwarding data packets between different networks. In simple terms, routers direct traffic between your company’s local area network (LAN) and the wider internet. They also provide security by creating a barrier between your internal network and the external world.

Switches:

Switches are responsible for connecting devices within your internal network. They create a bridge between different devices, allowing them to communicate with each other. Switches come in different sizes and configurations, depending on the size of your network. They are an essential component of enterprise networking, as they provide high-speed connectivity between devices.

Firewalls:

Firewalls are security devices that control and monitor incoming and outgoing network traffic. They act as a barrier between your internal network and the external world. Firewalls use a set of rules to determine which traffic is allowed and which is blocked. They are critical in protecting your company’s network from external threats, such as hackers and malware.

VPNs:

Virtual private networks (VPNs) allow remote users to securely connect to your internal network. They create an encrypted connection between the remote user’s device and your internal network, allowing them to access company resources securely. VPNs are essential in today’s remote work environment, as they allow employees to work from anywhere in the world while maintaining the security of your network.

LAN and WAN:

Local area networks (LANs) connect devices within a small geographic area, such as a single office building. Wide area networks (WANs) connect devices over a larger geographic area, such as multiple office locations or even different countries. WANs use routers to connect different LANs together, allowing them to communicate with each other.

In conclusion, understanding the fundamentals of enterprise networking is crucial for businesses to ensure efficient communication, security, and productivity. The key components of enterprise networking include routers, switches, firewalls, VPNs, and LAN and WAN. By working together, these components create a secure and efficient network that allows your business to thrive in today’s digital age.