Author: Asad Ijaz

NetworkUstad's lead networking architect with CCIE certification. Specializes in CCNA exam preparation and enterprise network design. Authored 2,800+ technical guides on Cisco systems, BGP routing, and network security protocols since 2018. Picture this: I'm not just someone who writes about tech; I'm a certified expert in the field. I proudly hold the titles of Cisco Certified Network Professional (CCNP) and Cisco Certified Network Associate (CCNA). So, when I talk about networking, I'm not just whistling in the dark; I know my stuff! My website is like a treasure trove of knowledge. You'll find a plethora of articles and tutorials covering a wide range of topics related to networking and cybersecurity. It's not just a website; it's a learning hub for anyone who's eager to dive into the world of bits, bytes, and secure connections. And here's a fun fact: I'm not a lone wolf in this journey. I'm a proud member and Editor of Team NetworkUstad. Together, we're on a mission to empower people with the knowledge they need to navigate the digital landscape safely and effectively. So, if you're ready to embark on a tech-savvy adventure, stick around with me, Asad Ijaz Khattak. We're going to unravel the mysteries of technology, one article at a time!"
Network switches exchanging BPDUs
CCNA October 22, 2019

802.1D Bridge Protocol Data Unit (BPDU) Frame Format

The spanning tree algorithm exchanges the Bridge Protocol Data Unit (BPDU) to elect the Root Bridge. It is a frame containing 12 different fields with different information. The information in the BPDU is used to determine the root bridge and the paths to the root bridge. The figure below illustrates the Bridge Protocol Data Unit […]
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Network switches calculating path costs
CCNA October 19, 2019

Spanning Tree Algorithm – Path Cost Exclusive Details

When a loop occurs in the switched network, the STP uses path cost to resolve the port’s state. Path cost is obtained from the port’s speed. The spanning tree puts the lowest-numbered port into the forwarding state if all connected ports have the same path cost values. The path information is determined using the sum […]
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Network diagram with switches, root bridge priority settings, and STP port roles (root, designated, blocked) labeled for clarity.
CCNA October 18, 2019

Spanning Tree – Root Bridge

Every spanning tree switched network or broadcast domain has a switch designated as the root bridge. It serves as the reference point for all spanning-tree-enabled switches. The spanning tree algorithm determines which redundant paths to block. It is selected as an election process. The figure below illustrates the bridge ID (BID) fields. BID is a […]
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CCNA October 17, 2019

Spanning Tree – Port Roles

IEEE 802.1D Spanning Tree Protocol (STP) and Rapid Spanning Tree Protocol (RSTP) use the Spanning Tree Algorithm (STA) to decide which switch ports on a network must be put in a blocking state to prevent loops. The Spanning Tree Algorithm designates one switch in the network as the root bridge. The root bridge is considered […]
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CCNA October 17, 2019

What is Spanning Tree Protocol

In the previous article, I have explained the redundancy. It increases the network availability by protecting the network from a single point of failure, such as a fault in a network cable or fault in a switch. When engineers introduce physical redundancy in design, loops and duplicate frames happen. I have written in the previous […]
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CCNA October 16, 2019

What is Network Redundancy? – Exclusive Explanation

Reliability is the quality of a computer network that consistently performs according to its specifications. It has long been considered one of three related attributes that must be considered when planning a network. Network Redundancy is one of the key factors to maintain network reliability. Multiple physical connections between network devices provide redundant network paths. […]
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CCNA October 15, 2019

What is NAT for IPv6 – Exclusive Details

NAT and private IPv4 addresses have slowed down the depletion of IPv4 addresses, but NAT has some disadvantages. The one major benefit provided by NAT is security. NAT hides the private IPv4 network from the public Internet, providing a perceived level of security by denying computers on the public Internet from accessing internal hosts. However, […]
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Diagram illustrating port forwarding with traffic from public IP to private web server through a router, showing port numbers and NAT configuration pathways.
CCNA October 13, 2019

Introduction to Port Forwarding including Its Configuration – Exclusive Explanation (Updated 2025)

Port forwarding is a critical networking technique that allows external devices to access services on a private network by directing traffic from a public IP address and port to a specific internal IP and port. For CCNA and CCNP students, understanding port forwarding is essential for configuring routers, securing networks, and enabling services like web […]
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CCNA October 13, 2019

How to Configure Port Address Translation (PAT)

Port Address Translation (PAT) is also known as NAT overload. Port Address Translation preserves addresses in the inside global address pool. Port Address Translation (PAT) allows the router to simultaneously use one inside global address for several inside local addresses. We can use a single public IPv4 address for hundreds, even thousands of internal private […]
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CCNA October 12, 2019

How to Configure Dynamic NAT

Dynamic NAT maps inside local addresses to inside global addresses automatically. The inside global addresses are usually public IPv4 addresses. Dynamic NAT uses a pool of public IPv4 addresses or a group of public IPv4 addresses for translation. Dynamic NAT also requires the configuration of the inside and outside interfaces participating in NAT, like static […]
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