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Network Design - Coggle Diagram
Network Design
11.2 Scalable Networks
Scalable networks are designed to support increasing users, devices, services, and locations without sacrificing performance or availability. They rely on modular design, redundancy, hierarchical addressing, and efficient routing.
A scalable design uses:
Modular devices (upgradable, stackable, clustered).
Hierarchical network structure (access/distribution/core expansion).
IPv4/IPv6 hierarchical addressing to prevent major re-addressing.
Layer 3 devices to reduce broadcasts and optimize traffic forwarding.
Scalability ensures the network grows easily while maintaining reliability.
Redundancy ensures network uptime by eliminating single points of failure:
Duplicate devices and links provide failover capability.
Redundant paths allow alternate routes for traffic.
Spanning Tree Protocol (STP) prevents Layer 2 loops when redundant links exist.
Layer 3 routing increases resilience with faster convergence and loop-free networks.
Redundancy is essential for business-critical environments.
Smaller failure domains reduce the number of users affected during outages.
Techniques:
Use enterprise-class hardware and redundant links.
Implement Layer 3 devices at the distribution layer to contain faults.
Deploy switch blocks (paired distribution switches with access switches split evenly).
This design isolates failures to specific segments, minimizing downtime and simplifying troubleshooting.
To prevent bottlenecks, bandwidth is increased using EtherChannel:
Combines multiple physical links into one logical aggregated link.
Uses existing ports—no expensive upgrades needed.
Provides higher throughput, load balancing, and redundancy.
EtherChannel improves performance between switches and reduces congestion.
Keywords: wireless expansion, mobility, flexible access, WAP deployment.
The access layer must grow to support more users and devices.
Wireless expansion offers:
Increased flexibility and mobility.
Lower installation costs.
Easy scaling for new areas or users.
Requirements:
End devices need a wireless NIC.
Network requires access points (APs) and proper wireless design (coverage, interference, security).
Advanced routing protocols improve performance in scalable networks:
OSPF (Link-State Routing) adapts well to large hierarchical topologies.
Routers form neighbor adjacencies and exchange link-state information.
Fast convergence recalculates best paths when topology changes occur.
Proper tuning ensures routing efficiency and stability as the network grows.
11.3 Switch Hardware
Switch hardware varies by platform, size, capacity, and features. Choosing the right switch depends on performance requirements, number of users, PoE needs, and network design (access, distribution, core).
Different platforms target specific environments:
Campus Switches: Used in access/distribution layers; support PoE, VLANs, stacking, and security features.
Data Center Switches: High throughput (40G/100G/400G), low latency, advanced L3, fabric support (VXLAN, EVPN).
Cloud-Managed Switches: Centralized management (e.g., Meraki) with monitoring, automation, and policy enforcement.
Industrial Switches: Ruggedized for harsh environments; extended temperature and vibration tolerance.
Fixed Configuration: Predefined ports; cost-effective; common in access layer.
Modular (Chassis-Based): Slots for line cards; highly scalable for core/distribution.
Stackable: Multiple fixed switches operate as one unit; centralized control; increased redundancy and port count.
Higher port density reduces equipment count and wiring complexity:
Access switches: 24 or 48 ports, often with PoE.
High-end switches: up to hundreds of ports using modular chassis.
Considerations: uplink types (1G/10G/40G), redundancy, and expected device growth.
Forwarding rates determine how many packets a switch can process:
Must support wire-speed forwarding on all ports simultaneously.
Higher layers (distribution/core) require higher throughput to handle aggregated traffic.
Multigigabit and 10G/40G switches need high forwarding capacity to prevent bottlenecks.
PoE allows power + data via Ethernet cables for devices like:
IP phones, Access Points, Cameras, IoT devices.
PoE standards:
PoE (802.3af): up to 15.4W
PoE+ (802.3at): up to 30W
UPOE / UPOE+: 60W–90W
Switches must have enough power budget to support all connected devices.
Multilayer switches combine switching and routing:
Perform Layer 2 forwarding (MAC-based) and Layer 3 routing (IP-based).
Provide SVIs (Switch Virtual Interfaces) for inter-VLAN routing.
Use ASICs for high-speed hardware-based routing.
Common in distribution and core layers for scalable, fast networks.
Selecting a switch depends on organizational needs:
Budget: initial cost + long-term maintenance.
Scalability: ability to add ports, power, or capacity later.
Performance Requirements: forwarding rate, uplink speeds, redundancy.
Power Needs: PoE for phones, cameras, APs.
Management: cloud-managed vs. on-premise.
Environment: data center, campus, industrial, or branch office.
Proper selection ensures performance, reliability, and cost-efficiency.
11.1. Hierarchical Networks
Access: connects end devices (PCs, VoIP, APs); provides VLANs, PoE, port security.
Distribution: policy control; inter-VLAN routing; ACLs; redundancy (HSRP/VRRP); link aggregation.
Core: high-speed, low-latency backbone; redundancy; simple, fast forwarding only.
Networks must accommodate more users, devices, locations, and services.
Scaling requires hierarchical IP addressing, modular equipment, Layer 3 routing, and centralized management.
Cisco Borderless Networks enable secure access for any device, anytime.
Policies, QoS, identity-based control, and mobility features unify LAN and WLAN environments.
Borderless networks use the same design principles:
Hierarchy: clear roles per layer.
Modularity: building blocks that scale independently.
Resiliency: redundant links/devices; fast convergence.
Flexibility: load sharing, multiple active paths (ECMP/EtherChannel).
Access: security (802.1X, port-security), VLANs, edge QoS, endpoint connectivity.
Distribution: ACLs, QoS policies, gateway SVIs, redundancy, route summarization.
Core: fast Layer 3 forwarding, high bandwidth, minimal features to preserve speed.
Three-tier: used in large campuses; separate layers for scalability.
Two-tier (collapsed core): merge core and distribution in smaller networks to reduce cost/complexity.
Modern switched networks support voice, video, wireless, and segmentation.
Functions include QoS prioritization, link aggregation, security features (802.1X, DHCP snooping), and telemetry.
L3 distribution reduces loops and dependency on STP.
11.4 Router Hardware
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Router requirements depend on the role of the router within the network:
Performance: CPU speed, memory, and throughput must support expected traffic loads.
Interfaces: Ethernet, fiber, serial, DSL, LTE, and modular WAN cards.
Scalability: Ability to upgrade modules, software, or licenses.
Security: Support for firewalls, VPNs, ACLs, IPS/IDS, and encryption.
High Availability: Redundant power, backup links, fast failover protocols.
Services: QoS, Network Address Translation (NAT), DHCP, routing protocols (OSPF, EIGRP, BGP).
Routers must be chosen to support both current business needs and long-term growth.
Cisco provides multiple router families designed for different environments:
ISR (Integrated Services Routers): Branch/office routers with security, VPN, switching, voice, and WAN services integrated.
ASR (Aggregation Services Routers): High-performance routers for service providers and large enterprises; support very high throughput and advanced routing (BGP, MPLS).
Meraki MX Routers: Cloud-managed security and SD-WAN appliances.
Catalyst 8000 Series: Modern enterprise routers with SD-WAN, security, and advanced routing capabilities.
Cisco routers are widely used due to reliability, modularity, and extensive software features.
Routers come in several form factors depending on deployment needs:
Fixed Configuration Routers: Predefined interfaces; cost-effective; used in small offices or branches.
Modular Routers: Support interchangeable modules for WAN links, security, and switching; used in medium and large networks.
Rack-Mounted Routers: Common in enterprise and data centers; standardized dimensions for scalability.
Virtual Routers (vRouters): Software-based; run in cloud or virtualization environments (CSR1000V, vMX); ideal for SD-WAN and cloud networking.
Industrial Routers: Ruggedized for harsh environments and outdoor deployments.
Form factor selection depends on scalability, environment, and required features.
Router hardware varies depending on performance needs, WAN technologies, and deployment location. Routers interconnect networks, forward packets using Layer 3 logic, and support services like security, QoS, VPN, and redundancy.