2101 Ch17: Small Network Basics

Introduction to Networks v7.0 - Build a Small Network

• Small networks are typically simple, with fewer devices and a single WAN connection (DSL, cable, or Ethernet).
• Maintaining a small network requires similar skills to larger networks, but may be managed by a local technician or a contractor.
• Device selection is crucial, considering cost, capacity, features (ports, backplane speed, security), and redundancy.
• Network speed and port types (e.g., 1 Gbps, 10 Gbps) influence network scalability without immediate refreshes.
• Network devices like switches and routers need operating systems supporting requirements like Layer 3 switching, NAT, Dynamic Host Configuration Protocol (DHCP), security, quality of service (QoS), and Voice over IP (VoIP).

IP Addressing for a Small Network

• All devices in an internetwork need a unique IP address.
• Devices like end-user devices, servers, and peripherals (printers, cameras) use IP addressing.
• Planning, documenting, and maintaining an IP addressing scheme based on device type is recommended for easier identification and troubleshooting.

Network Redundancy

• Redundancy in a small network is essential for maximizing reliability.
• Redundancy can be accomplished by installing duplicate equipment or links for critical areas.
• A secondary service provider can function as a backup for internet connectivity.

Traffic Management

• Network design should prioritize minimizing downtime and improving employee productivity.
• Network administrator should consider various traffic types.
• Quality of Service (QoS) should be implemented for classified traffic during congestion.

Common Applications

• Network applications facilitate communication.
• Examples are email clients, web browsers and application utilities for network resources access such as file transfers and printing.

Network Protocols

• Network protocols dictate data formats and procedures for various network functions.
• Common protocols are Dynamic Host Configuration Protocol (DHCP) for IP config, Domain Name System (DNS) for name resolution to IP address, File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), and Secure Shell (SSH).

Network Infrastructure

• The network infrastructure must support real-time applications.
• Existing network devices and cabling must be examined and confirmed suitable to the task.
• Upgrading components, cables, and hardware might be required.

VoIP and IP Telephony

• VoIP converts analog phone signals to digital IP packets.
• IP telephony, using dedicated servers, facilitates voice-to-IP conversion.

Real-time Applications

• Real-time applications need quality of service (QoS) to minimize latency issues. Protocols such as RTP (Realtime Transport Protocol) and RTCP (Real Time Transport Control Protocol) are useful here.

Network Documentation and Inventory

• Documentation (physical and logical topology), devices inventory and budget are required in network scaling.

Traffic Analysis and Protocol Analysis

• Documenting traffic requirements for various protocols, applications, and services is critical.
• Tools like Wireshark are valuable for capturing network traffic and analyzing its patterns.

Common Show Commands

• Common Cisco IOS show commands (e.g., show running-config, show startup-config, show version, show interfaces, show ip interface brief, show arp) provide valuable information on network operation and configuration.

Troubleshooting Methodologies

• A logical, consistent method, often adhering to the scientific method, is recommended for addressing network problems.
• Thorough documentation of events, procedures, and findings is crucial for addressing network problems.

IP Configuration on Hosts

• Checking and verifying IP addresses on hosts, using ipconfig (Windows) or ifconfig (Linux/Mac), is essential for troubleshooting.
• DHCP for automatic IP assignments
• Correct default gateway for communication

Troubleshooting Scenarios

• Common problems like duplex mismatch, IP address conflicts, and incorrect default gateways.
• Understanding duplex operations (half-duplex and full-duplex)

Network Connectivity Verification

• ping command to test Layer 3 connectivity between source and destination IP addresses.
• traceroute command identify where issues are located along network paths.

DNS Issues

• DNS translates domain names (e.g., www.cisco.com) to corresponding IP addresses.
• Problems with the DNS server can lead users to believe that the network is down.