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.

The subnet mask of an IP address determines which part of the IP is used for the network and which part is used for hosts. It’s usually represented as four numbers, like 255.255.255.0. To find the subnet mask:

– Look at the first few numbers of the IP address.
– If it’s 255, then that portion is part of the network. If it’s less than 255, that portion is for hosts.

Example
Suppose you have an IP address 192.168.1.100 and a subnet mask of 255.255.255.0. In this case, the first three numbers (192.168.1) represent the network, and the last number (100) is for hosts.

2. What is the subnet mask of 255.255.255.0 IP address

A subnet mask of 255.255.255.0 means that the first three parts of the IP address are used for the network, and the last part is used for hosts. This is often used in small home or office networks.

3. What is the formula for finding a subnet

The formula for finding a subnet involves bitwise operations. You can calculate it using binary arithmetic, but it’s usually done with subnet calculators or tools. One common formula is:

Number of subnets = 2^(number of bits borrowed for subnetting)

4. How do I create a subnet from an IP address

To create a subnet from an IP address, you need to determine how many bits you want to allocate for the subnet and how many for hosts. Then, you adjust the subnet mask accordingly. For example, if you have IP address 192.168.1.0 and want to create subnets with 16 hosts each, you’d use a subnet mask of 255.255.255.240, creating 16 subnets.

5. Why is subnet mask always 255

Subnet masks are not always 255; they vary depending on the network’s needs. However, in common subnet masks, 255 is used to indicate that a portion of the IP is reserved for the network.

6. How do I change my IP address to a subnet mask

You don’t change your IP address to a subnet mask; they serve different purposes. Your IP address identifies your device on a network, while a subnet mask helps route traffic within that network.

7. How do I manually set a subnet mask

You can manually set a subnet mask in your device’s network settings. For example, in Windows, you can go to Control Panel > Network and Sharing Center > Change adapter settings, then right-click on your network adapter, select Properties, and manually configure the subnet mask in the IPv4 properties.

8. Should the subnet mask be the same as the IP address

No, the subnet mask and IP address should not be the same. The subnet mask defines which part of the IP address belongs to the network and which part belongs to hosts. They have different values and purposes.

9. What subnet mask is needed if an IPv4

IPv4 addresses can have various subnet masks depending on the network’s requirements. There is no specific subnet mask for all IPv4 addresses; it depends on the subnetting scheme used in the network.

10. What does the subnet mask 255.255.255.0 tell a router

Yes, a subnet mask of 255.255.255.0 indicates to a router that the first three parts of the IP address are the network portion, and the last part is for host devices within that network.

11. How do I configure IPv4 and subnet mask

To configure IPv4 and subnet mask on your device, you can go to the network settings and enter the desired values. For example, in Windows, it’s done in the IPv4 properties of your network adapter.

12. What is the default subnet mask for an IP address of

The default subnet mask for an IP address depends on the IP address class. For example, for a Class C IP address (e.g., 192.168.1.1), the default subnet mask is usually 255.255.255.0.

13. Why is 192.168 always used

The 192.168 IP range is reserved for private networks, and it’s commonly used because it provides a large number of available IP addresses while not conflicting with public internet IP addresses.

14. What is the IP address 127.0.0.1 used for

The IP address 127.0.0.1 is the loopback address, and it always refers to the local device. It’s used for testing network functionality on your own device without involving an external network.

15. Is 192.168.0.0 allowed on the Internet

No, the 192.168.0.0 IP range is reserved for private networks and is not routable on the public internet. It’s used for internal networks within homes and organizations.

16. Why do some IP addresses start with 10

IP addresses that start with 10 (e.g., 10.0.0.0) are also reserved for private networks. They are often used in larger networks where more IP addresses are needed.

17. Which IP address should you not use

You should not use IP addresses that are reserved for special purposes, such as loopback addresses (127.0.0.0/8) or addresses designated for private networks (e.g., 10.0.0.0/8, 192.168.0.0/16).

18. What is the best subnet mask

The best subnet mask depends on your network’s requirements. There is no one-size-fits-all answer. The subnet mask should be chosen based on the number of hosts and subnets needed in your network.

19. How many subnets can a router have

A router can have as many subnets as it has available interfaces. Each interface can be associated with a different subnet.

20. Can two subnets have the same IP address

No, two subnets on the same network should not have the same IP address. Each IP address should be unique within a subnet to avoid conflicts.

21. Can two routers share the same subnet

Yes, two routers can share the same subnet, but they should be properly configured to avoid routing conflicts. This scenario is common in complex network setups.

22. What IP addresses can talk to each other

IP addresses within the same subnet can easily communicate with each other. Routers are used to enable communication between different subnets or networks.

23. Can someone have the same IP as you

Yes, multiple devices can have the same private IP address within different networks, but they cannot have the same public IP address on the internet.

24. How can I tell if two computers are on the same subnet

You can determine if two computers are on the same subnet by comparing their IP addresses and subnet masks. If they have the same network portion as defined by the subnet mask, they are on the same subnet.

25. What happens if 2 IP addresses are the same

If two devices on the same network have the same IP address, it can lead to network conflicts and communication

issues. Each device on a network should have a unique IP address.

26. Can someone with my IP address see my history

No, having the same IP address as you doesn’t give someone access to your browsing history. Your browsing history is stored on your device, not on the network.

27. Does everyone in my house have the same IP address

No, each device in your house typically has its own unique private IP address on your home network.

28. Does everyone on the same WiFi have the same IP

Devices connected to the same WiFi network may have similar IP addresses (i.e., they share the same network portion), but they have different host portions, making them unique on the network.

29. Do you always have the same IP address when you connect to the internet

No, your public IP address assigned by your Internet Service Provider (ISP) can change periodically. This is known as a dynamic IP address. However, some ISPs offer static IP addresses that do not change.

30. Does an IP address change with location

Yes, your public IP address can change based on your physical location and the network you’re connected to. Different networks and locations may assign different IP addresses.

31. Is an IP address tied to a computer or router

An IP address can be tied to either a specific computer or a router, depending on the network configuration. In a home network, the router typically assigns unique IP addresses to each device connected to it.

32. What do the four numbers in an IP address mean

The four numbers in an IP address represent different levels of hierarchy. For example, in the IP address 192.168.1.1, the first number (192) represents the network, the second (168) represents a subnet within that network, and the last two (1.1) represent individual devices within that subnet.

33. What is an IP address for dummies

An IP address is like a digital address for devices on a network. It helps them find and communicate with each other on the internet or within a local network.

34. How do I find the exact location of an IP address

Finding the exact physical location of an IP address is challenging and often requires specialized tools and cooperation from Internet Service Providers. It’s not something a regular user can easily do.

35. Is it illegal to track an IP address

Tracking an IP address for legitimate network management purposes is generally not illegal. However, using IP address tracking for malicious purposes, such as stalking or hacking, is illegal and unethical.

36. Can an IP be traced to an exact location

IP addresses can be traced to a general geographic location, such as a city or region, but pinpointing an exact physical address is usually not possible without cooperation from the ISP.

37. How do I find the location of a device using an IP address

To find the approximate location of a device using an IP address, you can use online IP geolocation services or tools. These services provide general geographic information based on the IP address’s registered location.

Learn more on Subnetting; How to Calculate a Subnet Mask from IP Address

Understand Host and Subnet Quantities

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/

To configure a Three-Tier design using Cisco commands, follow the steps below:

Configure the Core layer:

Configure the Core layer switches with high-speed links to provide the backbone of the network.
Configure the switchports connected to the Distribution layer switches as trunk ports.
Configure VLANs on the Core layer switches.

Sample Cisco commands:

interface GigabitEthernet0/1
switchport mode trunk
switchport trunk allowed vlan 10,20,30

Configure the Distribution layer:

Configure the Distribution layer switches with uplinks to the Core layer switches and downlinks to the Access layer switches.
Configure the switchports connected to the Core layer switches as trunk ports and the switchports connected to the Access layer switches as access ports.
Configure VLANs on the Distribution layer switches.

Sample Cisco commands:

interface GigabitEthernet0/1
switchport mode trunk
switchport trunk allowed vlan 10,20,30

interface GigabitEthernet0/2
switchport mode access
switchport access vlan 10

Configure the Access layer:

Configure the Access layer switches with uplinks to the Distribution layer switches.
Configure the switchports connected to end devices as access ports.
Configure VLANs on the Access layer switches.

Sample Cisco commands:

interface GigabitEthernet0/1
switchport mode access
switchport access vlan 10

interface GigabitEthernet0/2
switchport mode access
switchport access vlan 20

Configure Spanning Tree Protocol (STP):

Configure STP to prevent loops in the network.
Configure the Core layer switches as the root bridges for each VLAN.
Sample Cisco commands:

spanning-tree mode rapid-pvst
spanning-tree vlan 10,20,30 root primary

Configure Link Aggregation Control Protocol (LACP):

Configure LACP to provide link redundancy and load balancing between switches.
Sample Cisco commands:

interface GigabitEthernet0/1
channel-group 1 mode active

Configure VLANs:

Configure VLANs on the Core, Distribution, and Access layer switches to segment the network.
Assign ports to VLANs based on the device type and location.
Sample Cisco commands:

vlan 10
name Sales
vlan 20
name Engineering
vlan 30
name Marketing

Verify the configuration:

Verify the configuration by checking the switchport settings, VLAN configuration, and STP status.
Sample Cisco commands:

show interfaces GigabitEthernet0/1 switchport
show vlan brief
show spanning-tree vlan 10,20,30

By following these steps, you can configure a Three-Tier design using Cisco commands.

Follow a previous article on building a two tier campus network.
Design and Build a Two-Tier Campus Network Architecture

Follow this Cisco Validated Design for Inspiration.

Cisco Meraki has some good validated design ideas here.

One of the most critical aspects of network device management is authentication, which ensures that only authorized users can access network resources. In this article, we will discuss how to implement RADIUS authentication using Windows Server NPS (Network Policy Server) for network device management.

RADIUS (Remote Authentication Dial-In User Service) is a networking protocol that provides centralized authentication, authorization, and accounting (AAA) management for users who connect and use a network service. RADIUS is commonly used for wireless networks, VPNs, and network device management.

The protocol works by authenticating users based on their credentials, which are typically a username and password, and then granting or denying access to the network device based on the user’s authorization level.

Windows Server NPS is a RADIUS server that provides authentication, authorization, and accounting services to network devices. It enables organizations to control access to network resources by providing a centralized authentication and authorization mechanism. NPS is a powerful tool that can help organizations enforce security policies, restrict access to sensitive data, and monitor network activity.

To implement RADIUS authentication using Windows Server NPS for network device management, follow these steps:

Install and configure NPS: Install NPS on a Windows Server, and configure it to use RADIUS as the authentication protocol. You can use the NPS wizard to set up RADIUS authentication.

Configure network devices to use RADIUS: Configure your network devices to use RADIUS as the authentication protocol. You will need to provide the IP address of the NPS server, the shared secret, and the RADIUS port number.

Create network policies: In NPS, create network policies that define the conditions under which a user is granted access to the network device. Network policies are a set of rules that define who can access the network device, under what circumstances, and what level of access they have.

Configure authentication methods: Configure the authentication methods that NPS will use to authenticate users. You can use different authentication methods, such as EAP-TLS, PEAP-MSCHAPv2, or EAP-TTLS, depending on your security requirements.

Test the configuration: Test the RADIUS authentication configuration by attempting to access the network device. Verify that you can successfully authenticate, and that you are granted access according to your authorization level.

Implementing RADIUS authentication using Windows Server NPS for network device management provides several benefits. It provides a centralized authentication and authorization mechanism, making it easier to manage user access to network resources. It also enables organizations to enforce security policies, restrict access to sensitive data, and monitor network activity.

In conclusion, implementing RADIUS authentication using Windows Server NPS is an effective way to manage network devices securely. By following the steps outlined in this article, you can set up a robust authentication and authorization mechanism that can help protect your organization’s network resources from unauthorized access.

Create NPS using PowerShell cmdlets and enable RADIUS authentication on Cisco devices:

Creating NPS using PowerShell cmdlets:

Open PowerShell as an administrator.
Install the NPS module by running the following command:

Install-WindowsFeature NPAS-Policy-Server

Create a new NPS server by running the following command:

New-NpsRadiusServer -Name "NPS_Server_Name" -Address "NPS_Server_IP_Address" -AuthenticationPort 1812 -SharedSecret "NPS_Server_Shared_Secret"

Create a new NPS network policy by running the following command:

New-NpsNetworkPolicy -Name "Policy_Name" -TunnelType "VLAN" -EapTls -Enabled -Conditions @{UserGroups="Domain Users"} -AuthenticationMethods @{Eap="EapTls"}

Add the NPS server to Active Directory by running the following command:

 Add-Computer -DomainName "domain.com" -Credential "domain\admin" -Restart 

Enabling RADIUS authentication on Cisco devices:

Log in to the Cisco device using a console or SSH session.
Enter configuration mode by running the following command: enable

Configure the device to use RADIUS authentication by running the following command:

aaa new-model

Configure the RADIUS server by running the following command:

radius-server host "NPS_Server_IP_Address" auth-port 1812 key "NPS_Server_Shared_Secret"

Enable RADIUS authentication on the desired interfaces by running the following command:

interface "interface_name", followed by the command authentication login radius

By following these steps, you can create an NPS server using PowerShell cmdlets and enable RADIUS authentication on Cisco devices.

This provides a secure authentication and authorization mechanism for managing network devices.

Follow another guide I wrote sometime ago;
Network Device Management with RADIUS Authentication using Windows NPS

What is a Spanning Tree Protocol?

A Spanning Tree Protocol (STP) is a network protocol that prevents loops in a network topology by creating a logical tree-like structure of network links. This protocol is crucial because loops can cause broadcast storms, which can result in network congestion and ultimately, network failure.

There are several variations of the STP protocol, including the original STP, Rapid Spanning Tree Protocol (RSTP), and Multiple Spanning Tree Protocol (MSTP). These protocols differ in terms of their speed, complexity, and features.

Configuring a Spanning Tree with Cisco Commands

In this section, we will explain how to configure the STP protocol using Cisco commands. Specifically, we will use the example of configuring the RSTP protocol on a Cisco switch.

Enable RSTP on the switch
To enable RSTP on a Cisco switch, use the following command:

Switch(config)# spanning-tree mode rapid-pvst

This command enables the RSTP protocol on the switch and configures it to use the rapid-per-VLAN spanning tree (PVST) mode.

Configure the switch priority
Each switch in the network has a priority value, which determines the root bridge of the spanning tree. By default, the priority value is 32768. However, you can change this value using the following command:

Switch(config)# spanning-tree vlan  priority 

This command sets the priority value for a specific VLAN. For example, if you want to set the priority value for VLAN 10 to 16384, you would use the following command:

Switch(config)# spanning-tree vlan 10 priority 16384

Configure the root bridge
The root bridge is the switch that serves as the central point of the spanning tree. To configure a switch as the root bridge, use the following command:

Switch(config)# spanning-tree vlan  root primary

This command sets the switch as the root bridge for a specific VLAN. For example, if you want to set Switch 1 as the root bridge for VLAN 10, you would use the following command:

Switch(config)# spanning-tree vlan 10 root primary

Verify the spanning tree configuration
To verify the spanning tree configuration, use the following command:

Switch# show spanning-tree

This command displays information about the spanning tree, including the root bridge, port roles, and port states.

Conclusion

The Spanning Tree Protocol is an essential protocol for preventing network loops and ensuring network stability. In this article, we explained what the STP protocol is and how to configure it using Cisco commands. By following the steps outlined above, you can configure the RSTP protocol on a Cisco switch and ensure that your network is protected from loops and broadcast storms.

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.