Network Architecture & Routing Protocols

This is a technical network diagram illustrating the interconnection between several hardware components of an enterprise network infrastructure. The infographic uses a schematic layout where hardware devices are depicted as 3D isometric blocks, connected by multi-colored lines representing data paths or logical configurations. Each line is color-coded to correspond with a specific networking protocol or concept listed in the legends.

Orange lines in the diagram represent BGP routing sessions. BGP is the de-facto exterior gateway protocol of the internet, responsible for exchanging reachability information between autonomous systems. Within this topology, the Cisco ISR 4521 router establishes eBGP peers with upstream providers and iBGP sessions toward the internal network.

• Path-vector protocol using TCP port 179
• Attributes: AS_PATH, NEXT_HOP, LOCAL_PREF, MED
• Convergence relies on route reflectors in larger fabrics

Purple lines denote OSPF link-state advertisements. OSPF is an interior gateway protocol that computes shortest-path trees using Dijkstra's algorithm. In this deployment, OSPF runs within the enterprise fabric to provide fast convergence and loop-free routing between the distribution and access layers.

• Link-state protocol, areas 0 (backbone) through N
• Cost metric based on interface bandwidth
• Hello timer: 10s (default), Dead timer: 40s

Teal/Blue lines indicate VLAN trunking. VLANs segment the broadcast domain at Layer 2, allowing the Catalyst 3300-24P to isolate traffic by function (e.g., management, voice, data) while sharing the same physical infrastructure. Trunk ports use 802.1Q tagging to carry multiple VLANs.

• 802.1Q tag inserted between Source MAC and EtherType
• Native VLAN (typically 1) carries untagged traffic
• VTP optional; manual pruning recommended

Light Blue lines represent ACL filtering policies. ACLs enforce permit/deny rules at the firewall and switch levels, controlling which traffic may traverse between VLANs or enter/exit the network. The Cisco ASA 5500-X applies both standard and extended ACLs in this architecture.

• Standard ACL: match on source IP only (1–99)
• Extended ACL: match on source/dest IP, protocol, port (100–199)
• Implicit deny-all at the end of every ACL

Application-layer protocols carried over the network. HTTPS (green lines) represents encrypted web traffic terminated at the load balancer, while HTTP (gray lines) represents internal backend communication between the F5 BIG-IP and the application servers.

• HTTPS uses TLS 1.3 on TCP/443; offloaded at LB
• HTTP uses TCP/80 for internal health checks and backend pools
• F5 BIG-IP supports SSL termination, re-encryption, and pass-through

GENEVE encapsulates Layer 2 frames in UDP for network virtualization overlays. It provides a flexible, extensible tunnel format that supports multi-tenant environments. In this diagram, GENEVE tunnels connect virtualized segments across the physical underlay.

• UDP encapsulation, destination port 6081
• Variable-length option headers (TLV format)
• Compatible with VXLAN and NVGRE control planes

A single piece of hardware — like the Load Balancer or Switch — must handle multiple overlapping protocols and security rules simultaneously. The color-coded path visualization makes this multi-protocol reality explicit, aiding troubleshooting, documentation, and capacity planning.