Troubleshooting TechNotes
- IOS Implementation of the iBGP PE-CE Feature
- Troubleshoot BGP Neighbor Flaps with MTU
- Configure IP Addresses and Unique Subnets for New Users
- Next-Hop Mismatch and BGP Inactive Routes Tech Note
- Troubleshoot Common BGP Issues
- Describe Administrative Distance
- Configure BGP Routers for Optimal Performance and Reduced Memory Consumption
- Select BGP Best Path Algorithm
- Examine Border Gateway Protocol Case Studies
- BGP Peer Groups
- BGP Policy Accounting and BGP Policy Accounting Output Interface Accounting Features
- BGP Prefixes Filters with 4-byte AS Numbers
- Block One or More Networks From a BGP Peer
- Border Gateway Protocol (BGP) Optimal Route Reflection
- Use Multi-Exit Discriminator to Select Best Path for BGP Router
- How the bgp deterministic-med Command Differs from the bgp always-compare-med Command
- How to Block One or More Networks From a BGP Peer (ZIP - 43 KB)
- Removing Private Autonomous System Numbers in BGP
- Route Target Constraint
- The "%TUN-5-RECURDOWN" Error Message and Flapping EIGRP/OSPF/BGP Neighbors Over a GRE Tunnel
- Troubleshoot Flapping BGP Routes (Recursive Routing Failure)
- Troubleshoot High CPU Caused by the BGP Scanner or Router Process
- Troubleshoot Border Gateway Protocol Routes that Do Not Advertise
- Understand BGP RIB-Failure and BGP Suppress-Inactive Command
- Understand Next Hop Set in iBGP Advertisements on Nexus NX-OS vs Cisco IOS
- Understand and Troubleshoot CEF on Cisco IOS XE Routers
- Understand the Importance of BGP Weight Path Attribute
- Understanding Policy Routing
- Understand the Redistribution of OSPF Routes into BGP
- Understand Route Aggregation in BGP
- Unsupported Capabilites Cause BGP Peer Malfunction
- Use Regular Expressions in BGP
- What Does the "#%BGP-3-INSUFCHUNKS: Insufficient chunk pools for aspath" Error Message Mean?
- When Are ICMP Redirects Sent?
- Troubleshoot BGP Neighborship Connection Issues
- EIGRP on SVTI, DVTI, and IKEv2 FlexVPN with the "IP[v6] Unnumbered" Command Configuration Example
- Configure IP Addresses and Unique Subnets for New Users
- Describe Administrative Distance
- Configuration Notes for the Implementation of EIGRP over Frame Relay and Low Speed Links
- Understand and Use the Enhanced Interior Gateway Routing Protocol
- Filtering Routing Updates on Distance Vector IP Routing Protocols
- How Does Unequal Cost Path Load Balancing (Variance) Work in IGRP and EIGRP?
- Understand how the Passive Interface Feature Works in EIGRP
- Introduction to EIGRP
- OSPF and EIGRP Neighbor Loss, RIP and IGRP Update Loss after Upgrading to Cisco IOS 11.2 or Later
- Preventing Duplicate EIGRP Router IDs
- Redistributing Between Classful and Classless Protocols: EIGRP or OSPF into RIP or IGRP
- Configure Route Selection for Routers
- The "%TUN-5-RECURDOWN" Error Message and Flapping EIGRP/OSPF/BGP Neighbors Over a GRE Tunnel
- Troubleshoot EIGRP Common Issues
- Troubleshooting EIGRP (ZIP - 107 KB)
- Troubleshooting EIGRP
- Understanding IPX-EIGRP
- Understanding Policy Routing
- What Does the EIGRP DUAL-3-SIA Error Message Mean?
- When Are ICMP Redirects Sent?
- Configure IP Addresses and Unique Subnets for New Users
- Describe Administrative Distance
- Create IS-IS Topology from CLI Output of IOS-XR Router
- IS-IS Network Types and Frame Relay Interfaces
- IS-IS Network Types and Frame Relay Interfaces (ZIP - 52 KB)
- IS-IS Route Leaking Overview
- Intermediate System-to-Intermediate System (IS-IS) TLVs
- MTU Mismatch Problem in IS-IS
- Understanding IS-IS Pseudonode LSP
- Understanding Policy Routing
- Uses of the Overload Bit with IS-IS
- When Are ICMP Redirects Sent?
- Configure IP Addresses and Unique Subnets for New Users
- Describe Administrative Distance
- Behavior of RIP and IGRP When Sending and Receiving Updates
- Filtering Routing Updates on Distance Vector IP Routing Protocols
- How Does Unequal Cost Path Load Balancing (Variance) Work in IGRP and EIGRP?
- How Split Horizon Affects RIP/IGRP Routing Updates when Secondary Addresses Are Involved
- IGRP Metric
- OSPF and EIGRP Neighbor Loss, RIP and IGRP Update Loss after Upgrading to Cisco IOS 11.2 or Later
- Redistributing Between Classful and Classless Protocols: EIGRP or OSPF into RIP or IGRP
- Understanding Policy Routing
- When Are ICMP Redirects Sent?
- Why Doesn't RIP or IGRP Support Discontiguous Networks?
- Why Don't RIPv1 and IGRP Support Variable-Length Subnet Mask?
- Down-bit Ignore Feature in OSPFV2 PE-CE Scenario on Cisco NX-OS
- Guide to OSPF Application on the CSS 11000
- Configure IP Addresses and Unique Subnets for New Users
- Describe Administrative Distance
- Why OSPF Demand Circuit Keeps Bringing Up the Link
- Change of Default OSPF and IS-IS SPF and Flooding Timers and iSPF Removal
- Common Routing Problem with OSPF Forwarding Address
- Guide to OSPF Application on the CSS 11000
- Configure Initial Configurations for OSPF over Non-Broadcast Links
- OSPF Demand Circuit Feature
- OSPF External path selection: External Type-2 (E2) VS NSSA Type-2 (N2)
- Troubleshoot OSPF Neighbor Problems
- Understand OSPF Neighbor States
- Configure the OSPF Not-So-Stubby Area (NSSA)
- Redistribute OSPF Among Different OSPF Processes
- OSPF Virtual Links: Transit capability
- OSPF and EIGRP Neighbor Loss, RIP and IGRP Update Loss after Upgrading to Cisco IOS 11.2 or Later
- OSPF show Commands Respond Slowly
- OSPF, MTU and LSA Packing Tech Note
- Problems with Running OSPF in NBMA and Broadcast Mode over Frame Relay
- Redistributing Between Classful and Classless Protocols: EIGRP or OSPF into RIP or IGRP
- Redistributing Connected Networks into OSPF
- Suboptimal Routing When Redistributing Between OSPF Processes
- The "%TUN-5-RECURDOWN" Error Message and Flapping EIGRP/OSPF/BGP Neighbors Over a GRE Tunnel
- The Effects of the Forwarding Address on Type 5 LSA Path Selection
- Troubleshooting Duplicate Router IDs with OSPF
- Troubleshoot Common Problems with OSPF
- Understand Selection of Forwarding Address in OSPF
- Understanding OSPF LSA-ID Conflict : %OSPF-4-CONFLICTING_LSAID
- Understanding Policy Routing
-
What Do
%OSPF-4-ERRRCVError Messages Mean? - Understand Show IP OSPF Neighbor Command Output
- When Are ICMP Redirects Sent?
- Troubleshoot OSPF Neighbors Stuck in Exstart/Exchange State
- Troubleshoot Open Shortest Path First Route Database Issues
- Why Does the show ip ospf neighbor Command Reveal Neighbors Stuck in Two-Way State?
- Why Does the show ip ospf neighbor Command Reveal Neighbors in the Init State?
- Why Doesn't OSPF Form Adjacency on a PRI, BRI, or Dialer Interface?
- Configure IP Addresses and Unique Subnets for New Users
- Describe Administrative Distance
- Behavior of RIP and IGRP When Sending and Receiving Updates
- Filtering Routing Updates on Distance Vector IP Routing Protocols
- How Split Horizon Affects RIP/IGRP Routing Updates when Secondary Addresses Are Involved
- ICMPv6 Packet Types and Codes
- OSPF and EIGRP Neighbor Loss, RIP and IGRP Update Loss after Upgrading to Cisco IOS 11.2 or Later
- Redistributing Between Classful and Classless Protocols: EIGRP or OSPF into RIP or IGRP
- Understanding Policy Routing
- When Are ICMP Redirects Sent?
- Why Doesn't RIP or IGRP Support Discontiguous Networks?
- Why Don't RIPv1 and IGRP Support Variable-Length Subnet Mask?
Border Gateway Protocol (BGP)
Classless Interdomain Routing (CIDR)
Enhanced Interior Gateway Routing Protocol (EIGRP)
Integrated Intermediate System-to-Intermediate System (IS-IS)
Interior Gateway Routing Protocol (IGRP)
Multiprotocol BGP (MBGP)
Open Shortest Path First (OSPF)
Routing Information Protocol (RIP)
Cisco Optimized Edge Routing (OER)
- Interior Gateway Protocol (IGP)
- On-Demand Routing (ODR)
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- BGP Table Version 30/Sep/2013
- External LSA with Overlapping Subnets in OSPF 11/Nov/2013
- IP Subnet Calculator
- Local Host Routes Installed in the Routing Table on Cisco IOS and Cisco IOS-XR 10/Jul/2013
- NetPro Discussion Forums on LAN, Switching & Routing
- Policy Routing and Its Impact on ESP and ISAKMP Packets with Cisco IOS 30/Oct/2013
- Software Advisor - Choose The Software For Your Network Device
- BGP Route Reflection and Multiple Cluster IDs 14/Sep/2015
- Compare OSPF Forwarding Address Behaviour on IOS and IOS-XR 31/Jul/2018
- IOS XR BGP Best Practice: eBGP Transit AS Route Advertisment 19/Apr/2016
- IP OSPF MTU-Ignore Command 03/Dec/2015
- IS-IS Hello Padding Behavior 15/Dec/2015
- Message "IPRT-3-RIB_LOOP" - Resolution Loop Formed by Routes in RIB 13/Jan/2016
- Native Multicast Flow - Any-Source Multicast Model 12/Jan/2018
- OSPF Complex Error Message Troubleshooting 01/Apr/2015
- Configure a Next Hop IP Address for Static Routes 10/Jul/2023
- Troubleshoot the "OSPF Neighbor Down: Too Many retransmissions" Error Message 14/Jan/2016
- Use the BGP "Slow Peer" Feature to Resolve Slow Peer Issues 16/Jun/2015
- Why Can't I Browse the Internet when Using a GRE Tunnel? 10/Aug/2005