Full mesh formula: n(n-1)/2
Example: To create a mesh between 8 nodes, 8 * (8-1) / 2 = 28; 28 links are needed.
Legacy Hierarchical Design Model
Core – fast L2-switched backbone
Distribution – L3 switches
Access – dense L2 switches
This failed to address issues such as redundancy, Internet and remote access, and locating services.
Switch block design was introduced to add redundancy; this included redundant core and distribution switches and links per switch block.
Enterprise Composite Network Model
This new model was developed to address modern design considerations.
Campus backbone (previously the "core")
Building distribution (previously "distribution")
Building access (previously "access")
Server farm (for internal enterprise services)
WAN (internal links)
Service provider edge
Frame relay, ATM, PPP for private connectivity
Intelligent Information Network (IIN)
Phase 1: Integrated transport – the shift toward the ECN model
Phase 2: Integrated services – service virtualization (disassociation of services from individual machines)
Phase 3: Integrated applications – recognizing and combining high-layer traffic properties (for example, Network Access Control)
Services-Oriented Network Architecture (SONA)
SONA is the application of IIN ideas to enterprise networks.
Network infrastructure (IIN phase 1)
Interactive services (IIN phase 2)
Application (IIN phase 3)
Distance vector – a router will only exchange routes with a directly connected neighbor
Link-state – a router advertises a list of all its neighbors and its neighbors’ networks; routers run SPF to determine the best path