diff --git a/work/den_job_prep.md b/work/den_job_prep.md new file mode 100644 index 0000000..54cc617 --- /dev/null +++ b/work/den_job_prep.md @@ -0,0 +1,452 @@ +1. ACI shifts the focus from network-centric to application-centric configurations: + - Traditional networking focuses on configuring individual network devices (switches, routers) and protocols. + - ACI instead focuses on the applications and their requirements, abstracting away much of the underlying network complexity. + - This shift allows network administrators to think in terms of application needs rather than network topology. + +2. Network policies are defined based on application requirements: + - In ACI, you define what an application needs in terms of connectivity, security, and performance. + - These requirements are translated into network policies automatically. + - For example, you might specify that a web server needs to communicate with a database server on a specific port, and ACI will configure the necessary network settings. + +3. Applications are grouped into "End Point Groups" (EPGs): + - An EPG is a logical grouping of endpoints that require similar network policies. + - Endpoints can be physical servers, virtual machines, containers, or even individual IP addresses. + - EPGs abstract away the physical and logical topology, focusing instead on the application function. + +4. EPGs are collections of endpoints that share common policy requirements: + - All endpoints in an EPG are treated the same from a policy perspective. + - This simplifies policy management - instead of configuring policies for each individual endpoint, you configure them once for the EPG. + - For example, all web servers might be in one EPG, while all database servers are in another. + +5. Contracts define how EPGs communicate with each other: + - Contracts are the ACI equivalent of Access Control Lists (ACLs) in traditional networking. + - They specify which EPGs can communicate with each other and how. + - Contracts can define allowed protocols, ports, and even quality of service (QoS) settings. + - They follow a provider-consumer model: one EPG provides a contract, and another EPG consumes it. + +Example scenario: +Imagine a three-tier web application with web, application, and database layers. In ACI: +- You'd create three EPGs: Web-EPG, App-EPG, and DB-EPG. +- You'd then create contracts: + 1. Web-to-App contract (allows HTTP/HTTPS traffic) + 2. App-to-DB contract (allows specific database port traffic) +- The Web-EPG would consume the Web-to-App contract, and the App-EPG would provide it. +- The App-EPG would consume the App-to-DB contract, and the DB-EPG would provide it. + +This approach allows for intuitive, application-focused network design and management, with built-in security and scalability. + +--- + +# Cisco ACI: Network-Centric Guide + +## 1. Physical Topology: Leaf-Spine Architecture + +ACI uses a leaf-spine architecture: +- Leaf switches: Connect to end devices (servers, firewalls, load balancers) +- Spine switches: Interconnect all leaf switches +- Every leaf connects to every spine, creating a full mesh topology + +Benefits: +- Predictable latency +- High bandwidth +- No spanning tree protocol needed + +## 2. APIC (Application Policy Infrastructure Controller) + +- Centralized management and control plane +- Cluster of 3 or more controllers for high availability +- Manages all aspects of the ACI fabric + +## 3. Underlay Network: IS-IS and VXLAN + +- IS-IS (Intermediate System to Intermediate System) routing protocol used internally +- VXLAN (Virtual Extensible LAN) for network virtualization + - Allows layer 2 segments to extend across the layer 3 fabric + - 24-bit VNID (VXLAN Network Identifier) for segment identification + +## 4. Tenant Network Virtualization + +- Tenants: Logical containers for policies, services, and network segments +- VRF (Virtual Routing and Forwarding): Provides IP address space isolation +- Bridge Domains: Layer 2 forwarding domains, similar to VLANs +- Subnets: IP address ranges associated with Bridge Domains + +## 5. External Connectivity + +- L3Out: Connects ACI fabric to external layer 3 networks + - Supports BGP, OSPF, EIGRP, and static routing +- L2Out: Connects ACI fabric to external layer 2 networks + +## 6. Packet Flow + +1. Ingress leaf switch performs VXLAN encapsulation +2. Spine switches route based on VXLAN outer header +3. Egress leaf switch performs VXLAN decapsulation +4. Policy enforcement occurs at ingress and egress leaf switches + +## 7. Hardware Components + +- Nexus 9000 series switches + - 9300 platform for leaf switches + - 9500 platform for spine switches +- APIC appliances or virtual machines + +## 8. Key Protocols and Technologies + +- LLDP (Link Layer Discovery Protocol): Neighbor discovery +- CDP (Cisco Discovery Protocol): Cisco-specific neighbor discovery +- COOP (Council of Oracle Protocol): Endpoint location distribution +- MP-BGP EVPN: For multi-site deployments + +## 9. Multicast + +- Uses a modified version of PIM BiDir (Bidirectional Protocol Independent Multicast) +- Optimized for the leaf-spine architecture + +## 10. Quality of Service (QoS) + +- Implemented through Custom Queuing Classes (CQC) +- Policies can be applied at various levels (EPG, contract, etc.) + +Understanding these network-centric aspects is crucial for effectively designing, implementing, and troubleshooting an ACI fabric. + +--- + +Here’s an outline of all the topics we’ve discussed during our conversation: + +--- + +### **1. Cisco Nexus APIC Controllers Overview** +- **Basic Concepts**: Introduction to **Cisco Nexus APIC (Application Policy Infrastructure Controller)** and its role in Cisco ACI. +- **APIC Architecture**: Overview of **tenants**, **EPGs (Endpoint Groups)**, and **contracts** in Cisco ACI. +- **Network Abstraction and Centralized Policy Management**: How APIC abstracts the network and applies policies across the fabric. + +--- + +### **2. Endpoint Groups (EPGs)** +- **Definition and Purpose**: Logical grouping of endpoints (servers, VMs, containers) that share the same policies. +- **EPG Example**: Example of an EPG for a three-tier web application (Web, App, and Database EPGs). +- **Communication Between EPGs**: Using contracts to control traffic between EPGs and enforce policies. + +--- + +### **3. Tenants in Cisco ACI** +- **Tenant Overview**: Explanation of tenants as logical containers that provide isolation between different network segments. +- **Types of Tenants**: + - **Common Tenant**: Shared services across the entire fabric. + - **Infrastructure Tenant**: Used for fabric-level configurations. + - **User Tenants**: Representing departments, applications, or business units. +- **Example of Tenant Usage**: Different departments with isolated network and security policies. + +--- + +### **4. Contracts in Cisco ACI** +- **Purpose**: Contracts define rules for communication between EPGs. +- **Step-by-Step Guide for Creating Contracts**: + - How to create a contract, subjects, and filters. + - Attaching contracts to EPGs (providing and consuming contracts). +- **Example of Contract**: Setting up HTTP traffic between Web and App EPGs. + +--- + +### **5. Monitoring Contracts** +- **APIC GUI Monitoring**: Monitoring contracts in the APIC GUI and tracking communication between EPGs. +- **CLI Monitoring**: Using CLI commands to check contract usage, traffic, and faults. +- **REST API for Monitoring**: Programmatically monitor contract stats using the ACI REST API. +- **SNMP and Syslog**: Configuring SNMP traps and Syslog for external monitoring and logging. + +--- + +### **6. Viewing and Exporting Faults** +- **Viewing Faults**: + - APIC GUI: Viewing active and historical faults in the APIC interface. + - CLI: Checking fault details using CLI commands. + - REST API: Retrieving faults via API for automation and integration. +- **Exporting Fault Logs**: Steps to export fault logs to **CSV** or **JSON** formats for analysis and sharing. +- **Using Syslog and SNMP**: Sending faults to a Syslog server or SNMP traps for centralized monitoring. + +--- + +### **7. Resolving Faults** +- **Identifying Faults**: How to analyze fault details like severity, cause, and affected object. +- **Common Faults and Resolutions**: + - **Interface Down or Flapping**: Troubleshooting physical and configuration issues. + - **VPC Peer-Link Issues**: Fixing peer-link failures and keepalive issues. + - **Contract Denied or Misconfigured**: Resolving issues with blocked traffic due to incorrect contracts. + - **Node Unreachable**: Rebooting or reconfiguring unreachable fabric nodes. + - **Configuration Out of Sync**: Re-syncing fabric configurations with the APIC. + +--- + +### **8. Clearing Faults** +- **Clearing Faults via APIC GUI**: Acknowledge or clear faults from the APIC interface. +- **Clearing Faults via CLI**: Manually clearing faults using CLI commands. +- **REST API for Clearing Faults**: Using the API to programmatically clear faults. +- **Best Practices for Clearing Faults**: Ensure issues are resolved before clearing faults. + +--- + +### **9. Major Faults in Cisco ACI** +- **Common Causes of Major Faults**: + - **Misconfigured Contracts and Filters**: Issues with denied traffic. + - **Interface or Port Issues**: Speed/duplex mismatches, down interfaces. + - **VPC Misconfiguration**: Peer-link or keepalive failures. + - **Misconfigured Fabric Policies**: Problems with access policies or QoS settings. + - **Node Resource Utilization**: High CPU or memory utilization. + - **Configuration Out of Sync**: Mismatch between APIC and fabric node configurations. + - **Reachability Issues**: APIC or fabric node connectivity problems. + - **Firmware Bugs**: Issues introduced by software bugs. + +--- + +### **10. Updating Cisco ACI Firmware** +- **Step-by-Step Firmware Update Process**: + - **Pre-Upgrade**: Download firmware, back up configuration, verify compatibility. + - **Upgrade APIC Controllers**: Perform a rolling upgrade of APIC controllers. + - **Upgrade Fabric Nodes**: Upgrade leaf and spine switches, using ISSU to minimize downtime. + - **Post-Upgrade**: Verify versions, check health, and resolve faults. + +--- + +### **11. Common Issues During ACI Firmware Upgrade** +- **Fabric Nodes Failing to Upgrade**: Causes include insufficient disk space, corrupted firmware, or connectivity issues. +- **APIC Cluster Quorum Loss**: Loss of connectivity or sync issues during the APIC upgrade. +- **VPC Inconsistencies**: VPC peer-link or configuration mismatches after the upgrade. +- **Connectivity Issues Post-Upgrade**: Traffic loss due to policy enforcement problems or stale ARP/MAC entries. +- **Node Reboot Loops**: Continuous reboot cycles caused by firmware or hardware failures. + +--- + +### **12. Best Practices for Cisco ACI Firmware Upgrades** +- **Pre-Upgrade**: + - Validate compatibility and upgrade path. + - Back up the configuration and schedule a maintenance window. + - Test in a lab environment. +- **During the Upgrade**: + - Upgrade APIC controllers first. + - Use **ISSU** for Nexus switches. + - Monitor system health and logs. +- **Post-Upgrade**: + - Verify all nodes are upgraded. + - Monitor health and faults. + - Re-check connectivity and policies. + - Take a post-upgrade configuration backup. + +--- + +Re-syncing nodes in Cisco ACI ensures that any configuration discrepancies between the **APIC controller** and the fabric nodes (leaf or spine switches) are corrected. A **re-sync** forces the APIC to re-push the configuration to a node to ensure that the fabric nodes are in sync with the intended policies, contracts, and other configurations. + +Re-syncing nodes can be necessary when there are **configuration out-of-sync faults**, **node reachability issues**, or **after performing firmware upgrades** to ensure that all configurations have been applied properly. + +Here’s how to re-sync nodes in Cisco ACI using both the **APIC GUI** and **CLI**. + +--- + +### **1. Re-sync Nodes via APIC GUI** + +#### Step-by-Step Process: + +1. **Log into the APIC GUI**: + - Open your browser and log into the **APIC** using your credentials. + +2. **Navigate to the Fabric Membership**: + - On the left-hand menu, navigate to **Fabric** > **Inventory** > **Fabric Membership**. + - This page displays all the fabric nodes (both leaf and spine switches) and their status. + +3. **Check for Out-of-Sync Nodes**: + - Look for any **faults** related to configuration out-of-sync issues. + - You may notice specific **out-of-sync faults** for nodes that need to be re-synchronized with the APIC. + +4. **Select the Node to Re-sync**: + - In the **Fabric Membership** page, locate the node (leaf or spine) you want to re-sync. + - Right-click on the node or click on the node's options menu (three dots) next to the node’s name. + +5. **Re-sync the Node**: + - Select **Re-sync Config** from the dropdown menu. + - This will force the APIC to re-apply the current configuration to the selected node. + +6. **Monitor the Re-sync Process**: + - After initiating the re-sync, you can monitor the status of the process. + - Check for any faults or issues that may arise during the re-sync. + - Once complete, verify that the node is healthy and synchronized by checking its health score and ensuring that there are no out-of-sync configuration errors. + +--- + +### **2. Re-sync Nodes via CLI** + +#### Step-by-Step Process: + +1. **Access the APIC CLI**: + - SSH into your APIC controller using the following command: + ```bash + ssh admin@ + ``` + +2. **List the Fabric Nodes**: + - To see the current fabric nodes (leaf and spine switches) and their IDs, run: + ```bash + show fabric membership + ``` + - This will list all the nodes in the fabric and their **Node ID**. + +3. **Re-sync a Specific Node**: + - To re-sync a specific node, use the following command: + ```bash + fabric re-sync node + ``` + - Replace `` with the actual ID of the node you want to re-sync, which you obtained from the previous step. + +4. **Monitor the Re-sync Process**: + - After issuing the command, the APIC will push the configuration to the node and attempt to bring it in sync. + - Use the following command to monitor the node's synchronization status and check for faults: + ```bash + show fault + ``` + +5. **Verify Node Sync Status**: + - Once the re-sync is complete, ensure the node is healthy and that there are no out-of-sync errors by running: + ```bash + show fabric membership + ``` + +--- + +### **3. When to Re-sync Nodes?** + +Re-syncing nodes is commonly needed in the following situations: +- **Configuration Out-of-Sync Faults**: When the configuration on the node and APIC doesn’t match, re-syncing can resolve the mismatch. +- **Node Not Responding to Policy Changes**: If policy changes or new configurations are not reflected on a node, re-syncing forces the node to apply them. +- **After Firmware Upgrades**: After upgrading the firmware of APIC controllers or fabric nodes, re-syncing ensures that all configuration updates are properly applied. +- **After Node Reboots**: If a node was rebooted or brought back online, re-syncing ensures it fully re-joins the fabric with the correct configuration. + +--- + +### **4. Best Practices for Re-syncing Nodes** +- **Monitor Health and Faults**: Always monitor the node’s health and check for **faults** both before and after the re-sync. This will help identify potential issues that could prevent the node from re-syncing properly. +- **Re-sync During Maintenance Windows**: If possible, perform re-syncs during a **maintenance window**, especially if you're working with critical nodes, to minimize the impact on network performance. +- **Avoid Re-syncing Multiple Nodes at Once**: Re-sync nodes one at a time to avoid overwhelming the APIC and fabric with multiple configuration pushes at once. + +--- + +It sounds like you're ready to consolidate all the detailed information we've covered into a single, comprehensive artifact. Here’s a suggested outline to summarize everything about **Cisco ACI firmware upgrades**, focusing on **best practices**, **common issues**, and the **step-by-step process**. + +### **Artifact: Cisco ACI Firmware Upgrade Guide** + +--- + +#### **1. Introduction** +- **Purpose**: This guide outlines the recommended practices and step-by-step instructions for upgrading the firmware of Cisco ACI, including APIC controllers and Nexus leaf/spine switches. It also covers common issues, troubleshooting tips, and how to ensure a smooth and successful upgrade. +- **Audience**: Network engineers, administrators, and IT professionals responsible for managing and upgrading Cisco ACI infrastructure. + +--- + +#### **2. Pre-Upgrade Planning** +**Key Preparations Before Upgrading:** +- **Backup the Configuration**: Always back up the ACI fabric configuration before starting the upgrade. Navigate to **Admin > Import/Export > Config Export** in the APIC GUI. +- **Understand Compatibility**: Review the **ACI compatibility matrix** and release notes to ensure that the APIC and Nexus switches can be upgraded to the target version. +- **Review the Upgrade Path**: Ensure you're following the correct upgrade path, especially when moving between major versions. Some versions may require intermediate upgrades. +- **Check Disk Space**: Confirm that APIC controllers and Nexus switches have adequate disk space for the upgrade files using `show system internal flash` for switches. +- **Test in a Lab Environment**: If possible, simulate the upgrade in a test environment to identify potential issues. +- **Schedule a Maintenance Window**: Plan for downtime, notify stakeholders, and ensure that the upgrade is performed during a low-traffic period. + +--- + +#### **3. Step-by-Step Upgrade Process** + +**a. Download Firmware**: +- Download the firmware packages for **APIC controllers** and **Nexus switches (leaf and spine)** from the [Cisco Software Download Portal](https://software.cisco.com). +- Upload the firmware to the APIC by navigating to **Admin > Firmware > Firmware Repository**. + +**b. APIC Controller Upgrade**: +1. Navigate to **Admin > Firmware > Infrastructure Firmware**. +2. Start a rolling upgrade by selecting **Upgrade Now** or scheduling the upgrade. +3. Upgrade the APICs one by one to maintain cluster quorum. +4. Monitor the upgrade process and verify the firmware version after each APIC has been upgraded. + +**c. Nexus Leaf and Spine Switch Upgrade**: +1. Start by upgrading **spine nodes** first, then **leaf nodes**. +2. Use **In-Service Software Upgrade (ISSU)** where possible to minimize downtime. +3. Monitor the upgrade progress in **Admin > Firmware > Infrastructure Firmware**. +4. Verify that all fabric nodes are running the correct firmware version after the upgrade using `show version`. + +--- + +#### **4. Post-Upgrade Actions** + +**a. Verify the Firmware Versions**: +- Use the APIC GUI or `show version` on switches to ensure all nodes are running the correct firmware. + +**b. Health Checks**: +- Monitor the overall health of the fabric in **Fabric > Fabric Membership**. +- Check for new **faults** under **Monitoring > Faults** and resolve any major or critical issues. + +**c. Policy and Connectivity Validation**: +- Test critical applications and network policies to ensure EPGs and contracts are working as expected. Use connectivity tests (e.g., ping, traceroute) between endpoints. + +**d. Post-Upgrade Backup**: +- After verifying the upgrade, create a new backup of the ACI configuration using **Admin > Import/Export > Config Export**. + +--- + +#### **5. Common Upgrade Issues and Resolutions** + +**a. Fabric Nodes Failing to Upgrade**: +- **Symptoms**: Leaf or spine switches remain on the old firmware version. +- **Resolution**: Check for insufficient disk space or upload the firmware again. Ensure the correct upgrade path is followed. + +**b. APIC Cluster Quorum Loss**: +- **Symptoms**: One or more APIC controllers fail to rejoin the cluster. +- **Resolution**: Ensure that out-of-band management is properly configured. Reboot APICs or re-sync the database. + +**c. VPC Inconsistencies**: +- **Symptoms**: Virtual Port Channels stop functioning after the upgrade. +- **Resolution**: Review the VPC configuration and ensure peer links are up. Re-apply or reconfigure VPC settings if necessary. + +**d. Connectivity Issues**: +- **Symptoms**: Endpoints lose connectivity after the upgrade. +- **Resolution**: Check for stale ARP/MAC entries, clear them if necessary, and verify contract and policy enforcement. + +**e. Fabric Node Reboot Loops**: +- **Symptoms**: Nodes repeatedly reboot after the upgrade. +- **Resolution**: Reload firmware manually or replace faulty hardware if needed. + +--- + +#### **6. Best Practices for ACI Firmware Upgrades** + +**a. Upgrade APIC Controllers First**: Always upgrade the APICs before fabric nodes, maintaining cluster quorum. +**b. Use ISSU**: When upgrading Nexus switches, use **In-Service Software Upgrade** to minimize disruption. +**c. Upgrade in Phases**: For large environments, upgrade nodes in small batches. +**d. Monitor System Health**: Continuously monitor the health of the system during and after the upgrade, watching for critical faults or performance degradation. +**e. Review Release Notes and Known Bugs**: Stay informed about potential issues with the firmware version by reviewing Cisco's release notes and bug tracker. + +--- + +#### **7. Conclusion** +- **Summary**: Upgrading Cisco ACI firmware is essential for ensuring a secure and stable infrastructure. Following best practices and carefully monitoring the process helps mitigate risks, reduce downtime, and maintain network continuity. +- **Further Support**: Always consult Cisco’s technical documentation and reach out to Cisco TAC for assistance if any issues arise during the upgrade process. + +--- + +### **Appendices** + +- **ACI Firmware Compatibility Matrix**: (Insert link or reference to the Cisco matrix) +- **Useful CLI Commands**: + - Check current firmware version: + ```bash + show version + ``` + - Verify cluster health: + ```bash + acidiag health + ``` + - Check disk space on switches: + ```bash + show system internal flash + ``` + - Re-sync fabric configuration: + ```bash + fabric re-sync node + ``` + +---