Cisco 300-135 - Troubleshooting & Maintaining IP Networks

Explore troubleshooting methodology by identifying a problem, diagnosing the underlying cause, gathering information, analyzing data, ruling out possible causes, and proposing and verifying an effective solution.

Define the problem, gather and analyze data, propose hypotheses, and test solutions, using a structured network troubleshooting method that emphasizes elimination, experience, and back and forth between stages.

Apply common troubleshooting approaches across the OSI model, including top-down, bottom-up, divide and conquer, follow the path, spot the difference, and swap components.

Apply specific troubleshooting procedures within the module one methodologies to diagnose root causes and resolve IP network issues.

Apply a structured network troubleshooting process that defines the problem, gathers and analyzes information, forms and tests hypotheses, verifies results, and escalates as needed to isolate a single root cause.

Select a probable cause, gather information, escalate if needed, test hypothesis, assess impact and urgency, prepare a rollback plan, implement and verify solution, and document changes for lessons learned.

Diagnose internet connectivity issues by checking DNS server configurations, DHCP settings, and site reachability; update DNS server pools, verify changes, and document the resolution.

Adopt routine maintenance steps to enable more efficient troubleshooting and change how you maintain network devices to facilitate quicker issue resolution.

Learn common maintenance tasks for IP networks, including device changes, backups, monitoring, capacity planning, and documentation, with a focus on change control to aid troubleshooting.

Adopt saving, restoring, and archiving configurations to change how you maintain network devices and facilitate faster troubleshooting when issues arise.

Master saving, restoring, and archiving router configurations by copying startup config from flash, using configure replace, and implementing time-based archives to a TFTP server.

Document networks accurately with commands like show version, show cdp neighbors, and show interfaces to capture device details, IPs, port mappings, and time synchronization for reliable logs.

Label interfaces and cables with a consistent scheme to quickly locate issues. Describe interface connections and configure logging with timestamps to improve network documentation, inventories, IP addressing, and device configuration.

implement time services to synchronize clocks across network devices using a clock source and multiple servers. route logs to destinations like console, memory buffer, and flash memory with security levels.

Establish a network baseline to define normal behavior and detect anomalies, using NetFlow and IP tests to monitor traffic and trigger alerts. Emphasize user-focused communication to gather troubleshooting information.

Use basic IOS troubleshooting tools to explore key processes that occur in routers and switches, and understand how these processes aid troubleshooting at layer to layer 3.

Explore the layer 2 switching process for hosts in the same subnet, using ARP to learn MAC addresses, and how switches flood broadcasts and forward via default gateway when needed.

illustrates layer 3 routing by forwarding a packet through multiple routers, using routing table lookups and arp to learn next-hop mac addresses, while ip addresses remain constant.

Use pipe filtering to tailor show command output with include, exclude, and begin, pulling relevant data from commands like show ip route, show ip interface brief, and show running config.

Learn to filter Cisco show outputs with regular expressions, using the caret (carrot) character, the pipe, the dollar sign, and the asterisk to match beginnings, ends, and repeated patterns.

Redirect output to a file on a TFT server using piping, copy the output to a flash text file, verify the file exists, and append without overwriting.

Use ping and extended ping to test reachability from specific source interfaces, inspect routes with show ip route, assess fragmentation, and verify services by telnetting to a device on port.

Master hardware diagnostics with show processes CPQ to monitor CPU and memory usage, review interfaces and platform details, and use debug commands to diagnose real-time routing and ICMP issues.

Explore specialized troubleshooting tools that assist in diagnosing the underlying causes of network issues by applying utilities to routers and switches and building on basic troubleshooting theory.

Identify and use troubleshooting tools across problem definition and analysis phases. Leverage event notification, embedded event management, logging, and net flow to capture traffic, baselines, and perform configuration rollback.

Explore how a central syslog server helps verify ACLs block traffic by filtering outgoing but denied logs and identifying the host IP from TCAP packets.

Identify network congestion by using a span session to mirror traffic from gigabit interfaces, capture with Wireshark, and analyze traffic types causing buffer drops.

Use SNMP to gather device data and graph memory utilization over time with a network management system. Identify a memory leak when memory usage steadily rises.

Use net flow to locate congested traffic by enabling IP flow top talkers, top five by bytes on Ethernet 0.1, and identify the device consuming the most bandwidth.

Use Cisco IOS embedded event manager to monitor significant events and trigger actions via applets, defining patterns and logging messages or automating interface changes.

Begin module six by tackling Acme corporation's first troubleshooting scenario, solving the reported issues one by one using the methodologies discussed in earlier modules. Let's get started.

Analyze the Acme network’s four issues in a small setup—from router to distribution and access switches—covering server access, internet access, SSH, and IPv6 connectivity.

Troubleshoot trunk misconfigurations causing a host connectivity issue and dhcp failure. Verify trunk status and allowed vlans, then fix the trunk to restore server reachability.

Diagnose nat issues by verifying scope, confirming inside and outside interfaces, checking access lists and nat statements, and using show ip nat translations to fix misconfigurations.

Apply a top-down troubleshooting approach to fix an interface by verifying layer 3 connectivity and ping, checking layer 2 status, and enabling an administratively down port to restore ssh access.

Diagnose IPv6 addressing issues by comparing devices, enabling IPv6 auto configuration (router discovery) on Windows, and verifying global unicast addresses through ping and show commands.

Diagnose and resolve three network issues for Overseas Incorporated by examining their US-Europe network diagram. Apply systematic troubleshooting to each issue.

Examine the overseas incorporated network with four routers and dual internet links; diagnose why GW1 backup fails and why PC1 and PC2 lack internet connectivity.

Apply a bottom-up troubleshooting plan to verify routing tables and identify default routes learned from ospf and redistributed from bgp, then implement changes for a single default route.

Identify a BGP AS mismatch between GW2 and the ISP router, correct the neighbor AS, and verify BGP adjacency and OSPF redundancy.

Diagnose BGP neighbor issues by ensuring IP connectivity, correct neighbor statements, proper update-source loopback usage, and matching authentication while verifying routes and neighbor state.

Trace no internet connectivity from pcs to switches, inspect ip interface brief and mac addresses, and correct port security static mac mappings. Verify dhcp and ping to confirm the fix.

Troubleshoot port security by checking static vs dynamic MAC entries, address limits, and saved vs running configurations; verify interface status and MAC table for IP phone and PC connections.

Diagnose and resolve VLAN connectivity issues by inspecting trunk ports, DHCP settings, and VLAN 22 on switch one, recreating missing VLAN 22, and restoring PC connectivity to the DHCP server.

Troubleshoot VLANs by verifying database, interfaces, and trunk configurations; ensure correct VLAN assignments and native VLAN consistency, and guard against VLAN hopping and STP domain issues.

Analyze the Education Systems network diagram to identify and resolve critical issues quickly and efficiently through structured troubleshooting and problem-solving.

Analyze Education Systems Incorporated's network with two edge routers, a VPN to the branch, a distribution layer 3 switch, and two layer-2 switches to troubleshoot HQ connectivity and internet access.

Diagnose a branch office connectivity issue by testing Telnet and ping from headquarters, verify the vpn link, and apply spot the differences to troubleshoot interior routing.

Diagnose why the 10.0.0.30 branch network lacks a specific route on DSW and HQ, causing traffic to use the default route toward the internet; verify with show ip route.

Use show ip protocols to verify AIG or AP interfaces, fix the 10.3.0.0 misconfiguration, and verify route learning with show ip route and connectivity to HQ and the internet.

Troubleshoot EIGRP adjacency by checking AS number and k value mismatches, passive interfaces, authentication errors, filters, and subnet mask issues. Use show ip protocols and show ip eigrp neighbors.

Diagnose a redundant internet setup by validating BGP adjacency with both providers and troubleshooting an ISP failover, identifying an access-list misconfiguration on both interfaces.

Troubleshoot BGP failover by correcting extended access-list 100 entries to align source and destination addresses for ISP links, validate failover with simulated outages and ping tests.

Analyze Seven Seas Travel's network diagram to identify root causes of three reported issues and understand how the network operates while applying troubleshooting strategies.

Analyze the Seven Seas Travel Corporation network, focusing on HQ and three branch offices connected by tunnels, VRRP failover, and an IP SLA test that fails to start.

Troubleshooting redistribution between the branch and headquarters affects reachability to server 2, using show ip route, show ip protocols, and adjacency checks to identify routing issues.

Troubleshoot redistribution of OSPF into another protocol by assigning seed metrics, validating routing table entries, and using route maps, access lists, and show ip protocols to ensure proper advertising.

Troubleshoot fhrp tracking to ensure proper master failover by configuring interface tracking, verifying master status with show track, simulating uplink failure, and validating traffic rerouting via traces.

troubleshoot an ip sla test by checking configuration and status, schedule an icmp echo test, and verify activation and results with show ip sla and show ip sla statistics.