Cisco CCNA Study – Day 10 | Stuff that a middle age man is still learning

I found studying really interesting, I feel like I have covered so much data but there always seems like there is so much more to learn. There are a total of 309 lectures in the course and I have completed 223 of them and with 72% it is hard not to focus on how much more there is to learn and for me it is stressful. Then I look at my daughter and I can see that I have passed that on to her also.

This is where I have to remember that I will never know everything and I am learning the information to build my base of knowledge and while it increases that base, the base that I have built to this point of my career is pretty fantastic and there is little if nothing that I can’t grasp so what I continue to learn is just supporting my abilities to support others.

Section 31: WAN – Wide Area networks

VPN – Virtual Private Network
- A virtual tunnel between private networks across a shared public network
- Traffic is encrypted while traveling over the VPN
- Public internet connections are cheaper than physical links, so they will tend to be cheaper.
- Type
  - Site to site
    - Terminated between routers/firewalls
    - Invisible to nodes
    - Typically uses IPsec for encryption
  - Remote access
    - Client uses software to connect remotely to a location
    - Can access anywhere there is internet connectivity
    - Usually uses SSL and sometimes IPsec
- Configuration Options
  - IPsec Tunnel
    - Open standard IP tunnel
    - Does not support multicast
  - GRE (Generic Routing Encapsulation) over IPsec tunnel
    - adds support for multicast
  - IPsec VTI (Virtual Tunnel Interface)
    - Cisco proprietary Simplified Configuration
    - Support multicast
  - DMVPN (Dynamic Multipoint VPN
    - Cisco proprietary
    - Scalable simple hub and spoke config
    - Enables direct full mesh connectivity between all devices
  - FlexVPN
    - Cisco proprietary
    - Similar to DMVPN
    - Newer technology
  - GETVPN (Group Encrypted Transport VPN)
    - Cisco proprietary
    - Scalable centralized policy for VPN over non-public infrastructure (like MPLS)
WAN Connectivity Options
- Service provider will typically provide an SLA (Service Level Agreement)
  - Guarantees for uptime
  - Traffic delay
  - Loss on the link
- Leased Lines/Satellite
  - Connectivity to the internet
  - Direct Connectivity between offices
  - Connectivity between offices over VPN
  - Dedicated physical connection
  - Reserved bandwidth, not shared with anyone else
  - Bandwidth is available in both directions
  - Commonly lease from a service provider for a monthly fee
  - Common uses
    - point to point connectivity between two offices
    - data center providing multipoint connectivity between offices
    - Data center connected to the internet, providing Internet connectivity and option connectivity over Internet VPN
  - Leased line uses a serial connection
  - Common bandwidth options
    - North America
      - T1 – 1.544 Mbps
      - T2 – 6 Mbps
      - T3 – 45 mbps
      - T4 – 275 Mbps
    - Europe
      - E1 – 2Mbps
      - E2 – 8 Mbps
      - E3 – 34 Mbps
      - E4 – 140 Mbps
  - Typically provide an SLA for uptime, traffic delay and loss on the link.
  - typically more expensive
  - usually a longer lead time for installation
  - Satellite
    - Typically more expensive and low bandwidth, but maybe the only option in hard to reach areas.
- MPLS – Multi Protocol Label Switching
  - Shared core infrastructure at the service provider
  - Connectivity to the internet
  - Connectivity between the office over VPN
  - MPLS VPN
    - usually operate by a service provider
    - Can travel over the provider’s shared MPLS network
    - Different levels of SLA for uptime, traffic delay and loss are often available at different price point
    - Typically Ethernet connections to customer router
    - Provides full mesh topology by default
  - Layer 3 MPLS VPN
    - runs across the providers core
    - Customer routers do not run MPLS
    - Static routes or a routing protocol runs between the customer Edge and Provider Edge routers
    - Customer sites are in different IP subnets
  - Layer 2 MPLS VPN
    - Customer and provider routers do not peer with each other
    - provider network acts like a giant swtich
    - Customer sites are in the same IP subnet
    - Reason to use
      - required for clustering an app over WAN
      - useful for migrating hosts during Disaster Recovery
    - Terminology
      - VPLS – Virtual Private LAN service
        
        Multipoint Layer 2 VPN
      - VPWS – Virtual PseudoWire Service
        
        Point to point Layer 2 vpn
- Optical Fiber
  - More suitable then copper for long distances
  - Commonly used for backhaul connections for service providers
  - Types of FTTx Services
    - Fiber to the Home
    - Fiber to the Premises
    - Fiber to the aBuilding
    - Fiber to the Neighborhood
- SONET (North America)/SDH (rest of the world)
  - Standards used in service provider optical fiber networks
    - Sonet STS – SONET OC – SDH STM – Bit Rate Mbps
      - STS-1 – OC-1 – – 51.84
      - STS-3 – OC-3 – STM-1 – 155.52
      - STS-12 – OC-12 – STM-4 – 155.52
      - STS-48 – OC-48 – STM-16 – 2488.32
      - STS-192 – OC-192 – STM-64 – 9953.28
- DWDM – Dense Wavelength Division Multiplexing
  - Combines multiple optical signals into one optical signal transmitted over a shingle fiber strand
  - Allows more capacity to be added to existing infrastructure
  - Used in all modern long haul optical connections
- Dark Fiber
  - Unused fiber that was not needed by a service provider.
- WAN Backup and small Office Solutions
  - Options often aimed at home user Internet access
  - Typically do not carry a SLA that meets corporate levels
  - Can be used in smaller offices to connect to corporate network
    - DSL – Digital Subscriber Line
    - Cable
    - Wireless – Example 4G
- Legacy WAN Connectivity Options
  - PSTN – Public Switched Telephone Network
  - ISDN – Integrated Services Digital Network
  - Frame Relay
  - ATM – Asynchronous Transfer Mode
  - X.25
PPPoE – Point to Point Protocol over Ethernet
- Commonly used in DSL deployments
- Can be configured on either the DSL modem or the router
WAN Topology Options
- Hub and spoke (Star)
  - Advantages
    - Simplicity
    - Centralized security policy
  - Disadvantages
    - Single point of failure
    - Suboptimal traffic flow
- Redundant Hub and Spoke
  - Advantages
    - Removes single point of failure
    - centralized security policy
  - Disadvantages
    - Higher cost
    - suboptimal traffic flow
- Full Mesh
  - Advantages
    - Optimal Traffic flow
  - Disadvantages
    - Higher complexity and cost
- Partial Mesh
  - Advantages
    - Partial optimal traffic flow
  - Disadvantages
    - Her cost