CCDA NOTES

Drivers for "NEW" network architectures:

  • Application growth
  • Evolution from a simple network to an intelligent network
  • Increased expectations for the network
INN (Intelligent Information Network)
  • An integrated system: Integration of applications, middleware, and services.
  • Active participation: Allows the network to manage, monitor and optimize applications and delivery of service.
  • Policy enforcement: The network enforces policies linking business processes to network rules
The goal of IIN is to migrate the enterprise to an intelligent information network.

Three IIN Phases:
  1. Integrated transport: Groups voice, video and data into a single transport network
  2. Integrated services: Groups servers, services and data storage. Virtualization is important here
  3. Integrated applications: The applications become network "aware". This is known as Application Oriented Networking (AON)
SONA
SONA has three layers:
  1. Network infrastructure layer: Contains campus, LAN, WAN, data center, branch and facilitates the transport of services across the network. It also includes servers, storage and clients.
  2. Interactive service layer: Optimizes communications between applications and services. Network functions include:
  • Security
  • Identity
  • Voice
  • Virtualization 
  • QoS
    3.  Application Layer: Contains business and collaboration applications used by end users such as:
  • Enterprise resource planning
  • Procurement
  • Customer relationship
  • Unified messaging
  • Conferencing
The benefits of SONA are:
  • Functionality 
  • Scalability
  • Availability
  • Performance
  • Manageability
  • Efficiency 
The network life cycle has 6 phases: Prepare, Plan, Design, Implement, Operate, Optimize (PPDIOO)

PPDIOO offers  4 main benefits:
  1. Lowers cost of ownership
  2. Increases network availability 
  3. Improves business agility
  4. Speedy access to applications and services by imporving
  • Availability 
  • Reliability
  • Security
  • Scalability
  • Performance
Prepare Phase: Establishes organization and business requirements.
  • This phase creates a business case to establish financial justification for a network strategy 
Plan Phase: Identifies the network requirement
  • Performs a gap analysis
Design Phase: Based on technical business requirements. The network design provides:
  • Availability 
  • Reliability
  • Security
  • Scalability
  • Performance
Implement Phase: New equipment is installed and configured

Operate Phase: Maintains the networks day to day operational health
  • Managing
  • Monitoring
  • Routing maintenance
  • Managing upgrades
  • Managing performance
  • Identifying and correcting network faults
This phase is the designs final test

Optimize: Involves proactive network management
  • Identify and resolve issues before they affect the network
PPDIOO Methodology:
  1. Identify network requirements
  2. Characterize the existing network
  3. Design the network topology and solutions
Identify customer requirements:
  1. Identify current network applications and services
  2. Define the organizational goals
  3. Define the possible organizational constraints
  4. Define the technical goals
  5. Define the possible technical constraints.
Technical  Goals:
  • Improve network response time throughput 
  • Decrease failure and downtime
  • Simplify network management
  • Improve security
  • Access to mission critical applications
  • Technology refresh
  • Improve network scalability
Organizational Constraints:
  • Budget
  • Personnel 
  • Schedule
Technical Constraints:
  • Existing wiring does not support new technology
  • Bandwidth may not support new applications
  • Network must support existing legacy equipment
 Network Audit Tools:
  1. Existing documentation
  2. Existing network management software
  3. New network management tools
 Important show commands:

Show version: Shows general device information
Show tech support: Display general information about the router when it reports a problem

Network Performance Checklist:
  1. No shared Ethernet segments are saturated (no more than 40% utilization)
  2. New segments should be switched and not shared (Switch vs hub)
  3. No WAN links are saturated (70%)
  4. Response time less than 100ms ( less than 10ms on LANs)
  5. No more than 20% broadcast or multicast
  6. No more than one CRC error per MB of data
  7. On Ethernet segments less than 0.1% packets result in collisions
  8. Output queue drops are not exceeded (100 an hour)
  9. Input queue drops are not exceeded (50 an hour)
  10. Ignored packets no exceeded 10 in an hour
Pilot and Prototypes:

  • Prototype: Network is a subset of the full design, tested in an "isolated" environment. Prototype DOES NOT connect to the existing network.
  • Pilot: Is an "actual" LIVE location that serves as a test site before the solution is deployed.

Transmission Media:

 Media                                          Bandwidth                        Distance                    Price


Twisted Pair                                  Up to 1Gbps                  100m                         Inexpensive


Multimode Fiber                           Up to 1Gbps                  2km                           Moderate


SingleMode Fiber                         Up to 10Gbps                90km/40km               Expensive


Wireless                                       54Mbps                         500m at 1Mbps         Moderate



Enterprise Branch Profiles:

  • Single-tier: 50 users (Small)
  • Dual-tier: between 50 and 100 users (Medium)
  • Multi-tier: between 100 and 1000 users (Large)
Benefits of a Hierarchical Model:
  • Cost savings
  • Ease of understanding
  • Modular network growth
  • Improved fault isolation 
Hierarchical Network Design:



The Core Layer: Fast transport between distribution switches within the enterprise:

The Distribution Layer: Policy based connectivity

The Access layer: Workgroup and user connectivity
***********************************************************************************

Core Layer: High speed switching backbone
  • Fast transport
  • High availability 
  • Redundancy 
  • Fault tolerance
  • Low latency and good managebility
  • Avoidance of slow packet manipulation caused by filters
  • QoS
Distribution Layer: Isolation point between the network's access and core layers
  •  Policy
  • Redundancy 
  • QoS
  • Security filtering
  • Address or area aggregation or summarization
  • Departmental or workgroup access
  • Broadcast or multicast domain definition
  • Routing between vlans
  • Redistribution between routing protocols
  • Demarcation between static and dynamic routing protocols
Access Layer: Provides user access to local segments and the network
  • High availabilty
  • Port security
  • Broadcast suppression
  • QoS
  • rate limiting
  • ARP inspeciton
  • VACL
  • Spanning Tree
  • Trust marking
  • PoE for voice VLANs and wireless devices
 Wireless:

LWAP- Lightweight Access Point Protocol
  1. Standard for control messaging 
  • Setup
  • Authentication 
  • Operates between AP and WLC
Split MAC operation:
  • Control and data messages are split
  • LWAP communicated with the WLC using "control" messages over the wired network
  • LWAPP data messages are encapsulated and forwarded to and from wireless clients
LWAP MAC operation:
  • Beacons and probe response
  • Control-packet acknowledgment and transmission
  • Frame queuing and packet prioritization 
  • MAC layer data encryption/decryption
Control messages can be transported at layer 2 or layer 3
  • Layer 2 LWAPP tunnels use ethertype code 0XBBBB
  • Layer 3 LWAPP tunnels are used between the LWAP and the WLC
  • Messages from the WLC use UDP port 12223 for CONTROL MESSAGES
  • Messages from the WLC use UDP port 12222 for DATA MESSAGES
Access Points select WLCs in the following order:
  • Primary Controller
  • Secondary Controller
  • Tertiary Controller
  • Master Controller
  • The WLC with the most AP associations





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