1. Planning and Troubleshooting Routing and Switching

2. Overview Selecting Intermediate Devices
Planning an Internet Connectivity Strategy
Planning Routing Communications
Troubleshooting TCP/IP Routing

3. Lesson: Selecting Intermediate Devices
Types of Devices
When to Use Routing
Types of Networking Domains
What Are the Features of Switches?
Virtual LANs
Full-Duplex Transmission in Switched Environments
Guidelines for Selecting an Appropriate Intermediate Device

4. Types of Devices Device OSI layer Definition
Hub
Physical (layer 1)
Extends the network by retransmitting the signal
Does not process the data
Is invisible to the nodes
Switch
Data-link (layer 2)
Forwards frames according to the destination address
Uses temporary or virtual connections to connect source and destination ports
Router
Network (layer 3)
Used to link WANs and dissimilar LANs
Operates at the packet level
Sends packets based on packet addressing
Layer 3 switch
Network (layers 2 and 3)
Is a limited-purpose hardware-based IP router with bridging capabilities
Also performs layer 2 switching

5. When to Use Routing Use routing to: Traditional uses of routers
Isolate networks from each other
Provide a start for a secure network implementation
Traditional uses of routers
Connecting WANs
Segmenting LANs

6. Types of Networking Domains
Switch
Segment B
Hub
Segment A
Broadcast Domain
Collision Domain B
Collision Domain A

7. What Are the Features of Switches?
Switch feature
Benefits
Layer 3
Routes packets at layer 3
Forwards frames at layer 2
Cost
Substantially cheaper than similar performance routers
Hardware routing
Fast performance (near wire speed)
Minimal latency

8. VLAN ABE – Broadcast Domain VLAN CDFG – Broadcast Domain
Virtual LANs
Layer 3 Switch
VLAN 1
VLAN 2
Hub
Hub
Hub A B C D E F G
VLAN ABE – Broadcast Domain
VLAN CDFG – Broadcast Domain

9. Full-Duplex Transmission in Switched Environments
Frame A
Frame B
Frame C
Frame D
Full-duplex communication

10. Guidelines for Selecting an Appropriate Intermediate Device
Cost
Ease of implementation
Administration and troubleshooting sophistication
Protocol support
Layer 1 support
Speed
Functionality
Programmability

11. Planning an Internet Connectivity Strategy
Requirements for an Internet Connectivity Solution
NAT as a Solution for Internet Connectivity
ISA (Proxy) as a Solution for Internet Connectivity
Guidelines for Planning an Internet Connectivity Strategy

12. Requirements for an Internet Connectivity Solution
Internet connectivity requirements
Scalability and fault tolerance
Filtering
User access
Authentication
Bandwidth control
Time-of-day access
Extensibility and flexibility
Application connectivity

13. NAT as a Solution for Internet Connectivity
Why NAT is a good solution
Same security requirements for all users
Non-routed private network
Required private addressing
NAT Table
maps to

14. ISA (Proxy) as a Solution for Internet Connectivity
Why ISA (Proxy) is a good solution
Secure Internet and private network access
Routed or non-routed network
Cache web contents
Intranet
ISA (Proxy) Server
maps to

15. Guidelines for Planning an Internet Connectivity Strategy
Define the existing network structure
Define security requirements
Identify connectivity requirements
Select an appropriate solution

16. Planning Routing Communications
Determining the Appropriate Connection Method
Selecting a Routing Protocol
Guidelines for Planning Router Connectivity

17. Determining the Appropriate Connection Method
When used
Leased lines
Security is important
Speed and reliability are required
No budget constraints
Tunneling
No modem infrastructure
Demand-dial routing
On demand
Limited traffic
Per-instance fee pricing structure
Demand-dial
-persistent
Ample traffic
Flat fee pricing structure

18. Selecting a Routing Protocol
Criteria
Static routes
Routing information rarely changes
Small internetworks
Scalability not an issue
Manual updates required
RIP (dynamic)
Routing information constantly changes
Automatic routing table updates required
Existing routers use RIP
Design includes demand-dial interface
Maximum number of routers an IP packet will cross is 16
OSPF (dynamic)
Existing routers use OSPF
Design includes redundant paths between two subnets
Design has more than 50 subnets

19. Using IP Packet Filters
Corporate Headquarters
Branch Office
Interface B outbound filter
All other protocols
SNMP
Interface A inbound filter
Branch Office
ICMP
Interface C outbound filter
All other protocols
All protocols

20. Guidelines for Planning Router Connectivity
Identify the router connection method
Determine which connectivity options to use
Determine which routing protocol to use
Identify filter settings

21. Troubleshooting TCP/IP Routing
How to Isolate a Routing Problem
When to Use Each of the Troubleshooting Tools
Troubleshooting TCP/IP Routing

22. How to Isolate a Routing Problem
Inside-Out Strategy
Outside-In Strategy
Can you ping the remote host?
Can you tracert to remote host?
Can you access the failed system?
If problem still exists, check route configuration
Contact the administrator of the failed system
Check system configuration
Fix configuration problem
Determine where trace fails
Yes No
Is the IP configuration correct?
Correct the configuration
Use tracert to identify communication breakdown
Is the routing table accurate?
Correct/delete the incorrect route entries
Contact network support engineer
Can you ping the gateway?
Can you ping interior gateways?
Divide-by-Half : Isolate by ½ the connection issue, then isolate by ½ again

23. When to Use Each of the Troubleshooting Tools
Troubleshooting area
Utility to use
Local computer configuration
Hostname
Ipconfig
NetStat
Nbtstat
ARP
Network connections
NetDiag
Tracing paths
Tracert
Ping
Pathping
DNS
NSlookup