4.1 Troubleshoot device management
📘CCNP Enterprise – ENARSI (300-410)
FTP (File Transfer Protocol) and TFTP (Trivial File Transfer Protocol) are protocols used to transfer files between devices in a network. In Cisco device management, these are crucial for moving IOS images, configurations, or backups.
1. FTP (File Transfer Protocol)
Definition:
FTP is a protocol used to transfer files between a client (your computer) and a server over TCP/IP. It provides authentication and reliable file transfer.
Key Points for the Exam:
- Port numbers:
- Control channel: TCP 21 → used to send commands like
get,put,ls. - Data channel: TCP 20 → used to actually transfer the file.
- Control channel: TCP 21 → used to send commands like
- Modes:
- Active mode: Server connects back to the client to transfer data.
- Passive mode: Client initiates both control and data connections (more firewall-friendly).
Cisco Usage:
- Upload IOS images to a router/switch.
- Download configuration files from a network device to a server.
- Backup configurations to a central server for disaster recovery.
Example Commands:
Router> copy running-config ftp:
Address or name of remote host []? 192.168.1.10
Destination filename [running-config]? backup-config
Username: admin
Password: ****
2. TFTP (Trivial File Transfer Protocol)
Definition:
TFTP is a simpler version of FTP. It runs on UDP instead of TCP and does not require authentication, making it faster but less secure.
Key Points for the Exam:
- Port number: UDP 69 → only one port, very lightweight.
- No authentication: Anyone who can reach the TFTP server can transfer files.
- Used for: Quick configuration backup, IOS image transfer in labs or controlled environments.
- Not secure: Avoid in production networks unless secured by firewall or internal network.
Cisco Usage:
- Booting a router from a TFTP server.
- Uploading and downloading configurations quickly.
- Recovery of IOS images during device upgrade.
Example Commands:
Router> copy running-config tftp:
Address or name of remote host []? 192.168.1.20
Destination filename [running-config]? backup-config
3. Differences between FTP and TFTP
| Feature | FTP | TFTP |
|---|---|---|
| Protocol | TCP | UDP |
| Authentication | Yes (username/password) | No |
| Reliability | Reliable (TCP handshake) | Less reliable (UDP) |
| Speed | Slower | Faster |
| Security | More secure | Less secure |
| Typical Use Case | IOS upgrade, backup | Quick config backup |
4. Troubleshooting FTP/TFTP
When managing devices in a network, you may face issues transferring files. Here’s how to troubleshoot:
Step 1: Verify connectivity
- Ping the server:
Router> ping 192.168.1.10
- If ping fails → network or IP problem.
Step 2: Verify DNS
- FTP requires hostname resolution if using names instead of IPs.
Router> nslookup ftp-server.example.com
Step 3: Check firewall
- FTP uses TCP 21 and sometimes TCP 20.
- TFTP uses UDP 69.
- Make sure ACLs/firewalls allow traffic.
Step 4: Check credentials
- For FTP: username and password must be correct.
- For TFTP: ensure the file exists in the TFTP root directory.
Step 5: Debugging on Cisco
- FTP:
Router# debug ftp
- TFTP:
Router# debug tftp events
Step 6: Common Errors
| Error Message | Meaning | Solution |
|---|---|---|
Host not found | DNS issue | Check hostname/IP |
Access denied | FTP authentication failed | Check username/password |
Timed out | Firewall/ACL blocking traffic | Check ACL/firewall |
File not found | File does not exist on server | Check TFTP/FTP directory and name |
5. Exam Tips for CCNP ENARSI
- Know FTP uses TCP, TFTP uses UDP and port numbers (21/20 for FTP, 69 for TFTP).
- Understand authentication differences: FTP requires it, TFTP does not.
- Be able to troubleshoot using ping, ACLs, firewall rules, and debug commands.
- Know the copy commands for Cisco devices:
copy running-config ftp:copy running-config tftp:copy tftp: flash:(for IOS upgrade)
- Recognize errors and map them to connectivity, authentication, or permissions problems.
✅ Summary:
- FTP = reliable, authenticated, TCP → for IOS upgrade, config backup.
- TFTP = fast, unauthenticated, UDP → for quick config backup or lab testing.
- Troubleshoot using connectivity checks, ACL/firewall verification, correct credentials, and debug commands.
- Remember ports: FTP 21/20, TFTP 69.
