ML(Machine Learning)- is branch of AI that works with statistical part of AI. It helps computer to solve problem.
DL(Deep Learning)- this is enhancement of ML where computer learn and make decision.
AI(Artificial Intelligence)- make computer intelligent to perform function normally done by human. AI includes Computer Vision, Language Processing, Creative and summarization.
4. Machine Learning (ML), Data is provided so that machine can learn pattern
Major Shift
Instead of Data + Rules → Answer
New approach was Data + Answers → Model (The model learns the rules itself.)
Different algorithm learns different characteristics automatically.
Common ML Algorithms
Linear Regression
Logistic Regression
Decision Trees
Random Forest
SVM
K-Means Clustering
# ML life cycle
Collect Data
↓
Training
↓
Testing/Validation
↓
Deploy Model
↓
Inference (Prediction)
↓
Retraining (if needed)
How Machine Learns?
Supervised Learning
system is trained using labeled datasets.
E.g. AI predict network security threat by training datasets labeled as “safe” and “malicious”
Unsupervised Learning:
don’t use labeled data.
Useful for anomaly detection.
It enables the system to spot unusual traffic patterns that deviate from what’s considered normal,
potentially flagging a security breach without prior knowledge of what to look for.
Reinforcement Learning:
Dynamic learning process where the AI system learns form consequences of its actions,
trial-and-error learning method. In the context of network operation, system can refine network performance by adjusting configurations and polices in response to real-time feedback,
Deep Learning is the technique of using large neural networks with many hidden layers to solve complex problems. Here neural networks became very large with many layers:
Neural Network + Many Layers = Deep Learning
Benefit:
Image recognition
Speech recognition
Language understanding
Examples:
Google Photos
Siri
Face Recognition
Input
↓
Hidden Layer
↓
Hidden Layer
↓
Hidden Layer
↓
Hidden Layer
↓
Output
Deep Learning types:
CNN (Convolutional Neural Network) -->Specialized for images
(Face recognition, Medical imaging, CCTV analytics)
RNN (Recurrent Neural Network) Designed for sequential data.
Examples: Speech processing, Time-series forecasting (Mostly replaced by Transformers.
GAN (Generative Adversarial Network) Two neural networks compete:
Generator vs Discriminator, best for Image creation, Synthetic data generation
Transformer : The architecture behind modern LLMs.
Learn by rewards and penalties.(Examples: Robotics, Self-driving cars, Game-playing AI)
Agentic AI = (Group of AI Agents working together) Think + Plan + Act ,Purpose: Plans, reasons, and executes multi-step goals with minimal human guidance.
Augmented means made greater, larger, stronger, or added to in number, amount, or value
LLM know lot - they only know public internet data they don't know our personal data
step 1: retrieve relevant information from your own documents
step 2: inject that info into prompt as additional info or context
Retrieval-Augmented Generation (RAG) is a technique that helps alleviate the issue of hallucination and out-of-date answers in LLMs.
RAG combines the capabilities of a retrieval system and a generative model.
Rag benefit:
reduce hallucinating
keep knowledge up to date
cost effective
maintain data privacy
RAG has two pipeline:
Ingestion pipe line
information/data --- extract data --- split into chunk == embedding vector database (semantic search)
Retrieval pipeline
user - query - embedding api - embedding - semantic search- context - pass it to mode - augmentation - generation (answer)
When given a prompt, the retrieval system first fetches relevant documents or pieces of information from a large database or knowledge source. Then, the generative model uses this retrieved information to generate a response. This process ensures that the responses are grounded in the retrieved documents, which can help improve factual accuracy and reduce the likelihood of hallucination. The key advantage of RAG is that it anchors the model's responses to real-world information contained in the retrieved documents, making the responses more accurate and less prone to fabricating information.
This capability makes RAG systems particularly valuable for navigating complex technical documentation.
Instead of manually sifting through dense material, users can rely on the RAG system to extract relevant details and present them in a digestible format.
This not only speeds up the process of finding information but also ensures that the guidance provided is accurate and directly relevant to the task at hand,
as it's grounded in the actual content of the documentation.
You can leverage your own RAG system with most modern LLMs by simply drag-and-dropping a PDF document into the prompt and directing the LLM to consult the documentation when giving you the response. ChatGPT, Claude, and Gemini all support file uploads.
Here model did not learn your data during learning but learn real time
Based on various Cisco website and other online resources
Acces switches
Old Device
New Device
2960X/2960XR
catalyst 9200
3650/3850
catalyst 9300
4500-E series
catalyst 9400
Desktop switch
catalyst 9200CX
Cisco catalyst 9200 switch characteristic:
• Lower total stacking bandwidth
• Lower switching and forwarding capacity than catalyst 9300
• Powered by IOS XE Lite OS
• Only ethernet connectivity no fiber
• No application hosting support
Catalyst 9300
• Provides both fixed and modular uplink option
• Application hosting support
• Fiber and copper connectivity options
• Stacking upto 8 switches with power stacking
Catalyst 9400
• Multiple supervisor modules
• Modular chassis design for access layer, available in 4 ,7 and 10 slot chassis with multiple supervisor modules
• Dual Chassi stacking (StackWise virtual)
• Application hosting support
• Great for long-term investment protection.
Core switches
Old Device
New Device
3850-XS /4500
Catalyst 9500 series
6840 -X /6880-X
Catalyst 9500 series
6500-E/6807-XL
Catalyst 9600 series
Features 9500
• 1RU
• High performance
• Core layer device
• 1gig to 400Gig port speed
• Not stackable
Features 9600
• For high-capacity environment like campus core
• Come with big ACL, MAC and route table scales and buffers
• Rely on a centralized architecture
• 25.4 Tbs switching capacity
Wireless Controller
Old Device
New Device
WLC 5820
WLC 9800
WLC 9800 WLC Feature
• Cisco Catalyst 9800 hardware or VM
• 100 Gb bw
• 250 to 6000 ap
• 5k to 64K client.
Branch WAN Router
Old Device
New Device
ISR 4221 and 4321
catalyst 8200L
ISR 4321 and 4331
8200 Series
ISR 4351, 4431, 4451
8300 Series
WAN aggregation Router
Old Device
New Device
ASR 1000
Catalyst 8500
Catalyst 8500 and 8500L series switches
• 1RU or 3RU
• Fixed configuration, no expansion model
• This router focused on high performance and bandwidth compared to 8200 and 8300
2: “Erase Disk” - fresh new installation deleting existing data.
3: "Manual partitioning" – Customize partitions. – If you don’t want to delete existing data
Manual partitioning:
Create free space and click add following three partitions.
1: File System Partition : ESP (Efi System Partition)
Size: min 100Mb max 500Mb
use as VFAT
Mount point : N/A
It is a FAT formatted partition containing the primary EFI boot loader(s) for installed operating systems.
2: SWAP: use as swap
Size: 4Gb
use as Swap
Mount point : N/A
3: File systm partition used by OS
Size: Maximum (depending upon availability and requirement)
use as EXT4
Mount point : /
apt : advanced package tool
To update local package index with information from configured repositories, it downloads latest list of available packages and their versions but do not install or upgrade any packages.
Admin@Ubuntu#:~$ sudo apt-get update
To upgrade all currently installed packages on system to latest version.
Admin@Ubuntu#:~$ sudo apt-get upgrade
To check Ubuntu software version:
Admin@Ubuntu#:~$ lsb_release -a
------------- output start --------------------
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 24.04.2
LTS
Release: 24.04
Codename: noble
------------- output end --------------------
Admin@Ubuntu#:~$ cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=24.04
DISTRIB_CODENAME=noble
DISTRIB_DESCRIPTION="Ubuntu 24.04.2 LTS"
Sunday, November 10, 2024
Cisco Nexus Switch CLI Cheat Sheet
Running Several Command on Single line.
Nexus# Conf t; int eth 1/1; no switch port; no shut
- 802.11a: 5 GHz, up to 54 Mbps, shorter range.
- 802.11b: 2.4 GHz, up to 11 Mbps, longer range.
- 802.11g: 2.4 GHz, up to 54 Mbps, backward compatible with 802.11b.
- 802.11n: 2.4/5 GHz, up to 600 Mbps, uses MIMO technology.
- 802.11ac: 5 GHz, up to 3.46 Gbps, wider channels and MU-MIMO.
- 802.11ax (Wi-Fi 6): 2.4/5 GHz, higher efficiency and capacity.
Common Wireless Terms
- SSID: Service Set Identifier, the name of the wireless network.
- BSSID: Basic Service Set Identifier, the MAC address of the access point.
- WPA/WPA2/WPA3: Security protocols for wireless networks.
- Channel: The frequency used for communication, often overlapping in the 2.4 GHz band.
- MIMO: Multiple Input Multiple Output, technology that uses multiple antennas to improve performance.
Wireless Security Protocols
- WEP: Wired Equivalent Privacy, outdated and insecure.
- WPA: Wi-Fi Protected Access, improved security over WEP.
- WPA2: Enhanced security, uses AES encryption.
- WPA3: Latest security protocol, offers stronger encryption and protection against brute-force attacks.
Wireless Configuration Commands (Windows)
- Show available Wi-Fi networks:
netsh wlan show networks
- Connect to a Wi-Fi network:
netsh wlan connect name=""
- Disconnect from a Wi-Fi network:
netsh wlan disconnect
Wireless Troubleshooting Commands
- Ping the access point:
ping
- Check signal strength:
netsh wlan show interfaces
- View wireless network properties:
netsh wlan show profile "" key=clear
Common Wireless Issues
- Weak signal: Check distance from the access point, obstacles, and interference.
- Connection drops: Update drivers, check for interference, and signal strength.
- No internet access: Verify DHCP settings, check ISP connection, and router status.
Best Practices for Wireless Networking
- Use WPA3 for better security.
- Select less crowded channels (1, 6, 11 in 2.4 GHz).
- Position access points centrally to optimize coverage.
- Limit SSID broadcasting for sensitive networks.
- Regularly update firmware on access points and routers.
- 802.11a: 5 GHz, up to 54 Mbps, shorter range.
- 802.11b: 2.4 GHz, up to 11 Mbps, longer range.
- 802.11g: 2.4 GHz, up to 54 Mbps, backward compatible with 802.11b.
- 802.11n: 2.4/5 GHz, up to 600 Mbps, uses MIMO technology.
- 802.11ac: 5 GHz, up to 3.46 Gbps, wider channels and MU-MIMO.
- 802.11ax (Wi-Fi 6): 2.4/5 GHz, higher efficiency and capacity.
Common Wireless Terms
- SSID: Service Set Identifier, the name of the wireless network.
- BSSID: Basic Service Set Identifier, the MAC address of the access point.
- WPA/WPA2/WPA3: Security protocols for wireless networks.
- Channel: The frequency used for communication, often overlapping in the 2.4 GHz band.
- MIMO: Multiple Input Multiple Output, technology that uses multiple antennas to improve performance.
Wireless Security Protocols
- WEP: Wired Equivalent Privacy, outdated and insecure.
- WPA: Wi-Fi Protected Access, improved security over WEP.
- WPA2: Enhanced security, uses AES encryption.
- WPA3: Latest security protocol, offers stronger encryption and protection against brute-force attacks.
Wireless Configuration Commands (Windows)
- Show available Wi-Fi networks:
netsh wlan show networks
- Connect to a Wi-Fi network:
netsh wlan connect name=""
- Disconnect from a Wi-Fi network:
netsh wlan disconnect
Wireless Troubleshooting Commands
- Ping the access point:
ping
- Check signal strength:
netsh wlan show interfaces
- View wireless network properties:
netsh wlan show profile "" key=clear
Common Wireless Issues
- Weak signal: Check distance from the access point, obstacles, and interference.
- Connection drops: Update drivers, check for interference, and signal strength.
- No internet access: Verify DHCP settings, check ISP connection, and router status.
Best Practices for Wireless Networking
- Use WPA3 for better security.
- Select less crowded channels (1, 6, 11 in 2.4 GHz).
- Position access points centrally to optimize coverage.
- Limit SSID broadcasting for sensitive networks.
- Regularly update firmware on access points and routers.
Windows Command Cheat Sheet for Network Engineers
Windows Command Cheat Sheet for Network Engineers
Basic Networking Commands
- Check IP configuration:
ipconfig
- Release IP address:
ipconfig /release
- Renew IP address:
ipconfig /renew
- Display current TCP/IP connections:
netstat -a
- Show routing table:
route print
Network Diagnostics
- Ping a host:
ping
- Trace the route to a host:
tracert
- Check DNS resolution:
nslookup
- Check network statistics:
netstat -s
Network Share and File Commands
- List shared folders:
net share
- Map a network drive:
net use : \\\
- Disconnect a network drive:
net use : /delete
Firewall Configuration
- Check firewall status:
netsh advfirewall show allprofiles
- Allow a program through the firewall:
netsh advfirewall firewall add rule name="" dir=in action=allow program=""
- Block a program:
netsh advfirewall firewall add rule name="" dir=in action=block program=""
Wi-Fi Commands
- Show Wi-Fi profiles:
netsh wlan show profiles
- Connect to a Wi-Fi network:
netsh wlan connect name=""
- Disconnect from a Wi-Fi network:
netsh wlan disconnect
Network Adapter Management
- Show network adapters:
getmac
- Disable a network adapter:
netsh interface set interface "" admin=disabled
- Enable a network adapter:
netsh interface set interface "" admin=enabled
Viewing and Managing Services
- List all services:
services.msc
- Start a service:
net start
- Stop a service:
net stop
PowerShell Networking Commands
- Check IP configuration:
Get-NetIPConfiguration
- Get DNS settings:
Get-DnsClientServerAddress
- Get active network connections:
Get-NetTCPConnection
- List files:
ls
- Change directory:
cd
- Print working directory:
pwd
- Create a directory:
mkdir
- Remove a directory:
rmdir
- Remove a file:
rm
- Copy a file:
cp
- Move or rename a file:
mv
- Display file contents:
cat
- Display file contents page by page:
less
- Search for a string in a file:
grep
- Count lines, words, and characters:
wc
- Sort lines in a file:
sort
- Display unique lines:
uniq
- Replace text in a file:
sed 's/old_text/new_text/g'
Networking
- Check network configuration:
ifconfig
- Display current IP address:
hostname -I
- Ping a host:
ping
- Check open ports:
netstat -tuln
- Trace the route to a host:
traceroute
Process Management
- List running processes:
ps aux
- Find a process by name:
pgrep
- Kill a process:
kill
- Kill a process by name:
pkill
- View system resource usage:
top
System Information
- Show disk usage:
df -h
- Show memory usage:
free -h
- Show system uptime:
uptime
- Show current users:
who
- Clear terminal screen:
clear
- Display current date and time:
date
- Get help for a command:
man
- Exit the terminal:
exit
Bash Command Cheat Sheet
Bash Command Cheat Sheet
File and Directory Commands
- List files:
ls
- Change directory:
cd
- Print working directory:
pwd
- Create a directory:
mkdir
- Remove a directory:
rmdir
- Remove a file:
rm
- Copy a file:
cp
- Move or rename a file:
mv
- Display file contents:
cat
- Display file contents page by page:
less
- Search for a string in a file:
grep
- Count lines, words, and characters:
wc
- Sort lines in a file:
sort
- Display unique lines:
uniq
- Replace text in a file:
sed 's/old_text/new_text/g'
Networking
- Check network configuration:
ifconfig
- Display current IP address:
hostname -I
- Ping a host:
ping
- Check open ports:
netstat -tuln
- Trace the route to a host:
traceroute
Process Management
- List running processes:
ps aux
- Find a process by name:
pgrep
- Kill a process:
kill
- Kill a process by name:
pkill
- View system resource usage:
top
System Information
- Show disk usage:
df -h
- Show memory usage:
free -h
- Show system uptime:
uptime
- Show current users:
who
- BGP (Border Gateway Protocol): The protocol used to exchange routing information between different autonomous systems (AS).
- Autonomous System (AS): A collection of IP networks and routers under a single organization's control.
- BGP Peers: Routers that exchange BGP routing information.
- BGP Session: TCP connection between BGP peers (port 179).
BGP States
1. Idle
2. Connect
3. Active
4. OpenSent
5. OpenConfirm
6. Established
BGP Attributes
- AS_PATH: List of ASs a route has traversed.
- NEXT_HOP: Next hop IP address for the route.
- LOCAL_PREF: Indicates the preferred exit point from the AS.
- MED (Multi-Exit Discriminator): Suggests preferred entry point to an AS.
- COMMUNITY: A way to group routes for routing decisions.
- Show BGP Summary:
show ip bgp summary
- Show BGP Routes:
show ip bgp
- Show BGP Neighbor Details:
show ip bgp neighbors
BGP Route Filtering
- Disallow Specific Routes:
neighbor filter-list in
- Using Route Maps:
route-map permit
match
set
BGP Timers
Adjust BGP Keepalive and Hold Timers:
neighbor timers
Example:
neighbor 192.168.1.1 timers 30 90
BGP Best Path Selection Criteria
1. Highest Weight (Cisco-specific)
2. Highest Local Preference
3. Shortest AS Path
4. Lowest Origin Type (IGP < EGP < Incomplete)
5. Lowest MED
6. EBGP over IBGP
7. Lowest IGP metric to NEXT_HOP
8. Oldest route (if all else is equal)
9. Lowest BGP router ID (if all else is equal)
Common BGP Commands for Troubleshooting
- Check BGP Neighbors:
show ip bgp neighbors
- BGP Route Information:
show ip bgp
- Check BGP Updates:
show ip bgp updates
BGP Cheat Sheet
BGP Cheat Sheet
Basic Concepts
- BGP (Border Gateway Protocol): The protocol used to exchange routing information between different autonomous systems (AS).
- Autonomous System (AS): A collection of IP networks and routers under a single organization's control.
- BGP Peers: Routers that exchange BGP routing information.
- BGP Session: TCP connection between BGP peers (port 179).
BGP States
1. Idle
2. Connect
3. Active
4. OpenSent
5. OpenConfirm
6. Established
BGP Attributes
- AS_PATH: List of ASs a route has traversed.
- NEXT_HOP: Next hop IP address for the route.
- LOCAL_PREF: Indicates the preferred exit point from the AS.
- MED (Multi-Exit Discriminator): Suggests preferred entry point to an AS.
- COMMUNITY: A way to group routes for routing decisions.
- Show BGP Summary:
show ip bgp summary
- Show BGP Routes:
show ip bgp
- Show BGP Neighbor Details:
show ip bgp neighbors
BGP Route Filtering
- Disallow Specific Routes:
neighbor filter-list in
- Using Route Maps:
route-map permit
match
set
BGP Timers
Adjust BGP Keepalive and Hold Timers:
neighbor timers
Example:
neighbor 192.168.1.1 timers 30 90
BGP Best Path Selection Criteria
1. Highest Weight (Cisco-specific)
2. Highest Local Preference
3. Shortest AS Path
4. Lowest Origin Type (IGP < EGP < Incomplete)
5. Lowest MED
6. EBGP over IBGP
7. Lowest IGP metric to NEXT_HOP
8. Oldest route (if all else is equal)
9. Lowest BGP router ID (if all else is equal)
Common BGP Commands for Troubleshooting
- Check BGP Neighbors:
show ip bgp neighbors
- BGP Route Information:
show ip bgp
- Check BGP Updates:
show ip bgp updates
# Comments
# This is a comment
# Variables
x = 5
name = "Alice"
# Data Types
integer = 10
float_num = 10.5
string = "Hello"
boolean = True
list_example = [1, 2, 3]
tuple_example = (1, 2, 3)
dict_example = {"key": "value"}
Control Structures
# If Statements
if x > 0:
print("Positive")
elif x < 0:
print("Negative")
else:
print("Zero")
# Loops
# For Loop
for i in range(5):
print(i)
# While Loop
while x < 5:
x += 1
# Reading a File
with open('file.txt', 'r') as file:
content = file.read()
# Writing to a File
with open('file.txt', 'w') as file:
file.write("Hello, World!")
Exception Handling
try:
# Code that may raise an exception
result = 10 / 0
except ZeroDivisionError:
print("You can't divide by zero!")
finally:
print("This will always execute.")
Modules and Packages
# Importing Modules
import math
from datetime import datetime
Decorators
def my_decorator(func):
def wrapper():
print("Before the function.")
func()
print("After the function.")
return wrapper
@my_decorator
def say_hello():
print("Hello!")
Generators
def countdown(n):
while n > 0:
yield n
n -= 1
for number in countdown(5):
print(number)
# Install a Package
pip install package_name
# Run a Python Script
python script.py
Python Cheat Sheet
Python Cheat Sheet
Basic Syntax
# Comments
# This is a comment
# Variables
x = 5
name = "Alice"
# Data Types
integer = 10
float_num = 10.5
string = "Hello"
boolean = True
list_example = [1, 2, 3]
tuple_example = (1, 2, 3)
dict_example = {"key": "value"}
Control Structures
# If Statements
if x > 0:
print("Positive")
elif x < 0:
print("Negative")
else:
print("Zero")
# Loops
# For Loop
for i in range(5):
print(i)
# While Loop
while x < 5:
x += 1
# Reading a File
with open('file.txt', 'r') as file:
content = file.read()
# Writing to a File
with open('file.txt', 'w') as file:
file.write("Hello, World!")
Exception Handling
try:
# Code that may raise an exception
result = 10 / 0
except ZeroDivisionError:
print("You can't divide by zero!")
finally:
print("This will always execute.")
Modules and Packages
# Importing Modules
import math
from datetime import datetime
Decorators
def my_decorator(func):
def wrapper():
print("Before the function.")
func()
print("After the function.")
return wrapper
@my_decorator
def say_hello():
print("Hello!")
Generators
def countdown(n):
while n > 0:
yield n
n -= 1
for number in countdown(5):
print(number)
Control Plane Policing (CoPP) is a network security feature used in Cisco devices and other network equipment to protect the control plane of the device. The control plane is responsible for managing and maintaining the device's routing and switching functions, it works like Brain of network device. Protecting the control plane is essential to ensure the stability and security of a network device.
Control Plane Policing is designed to prevent unauthorized or malicious traffic from overwhelming the control plane and causing network disruptions. It involves setting limits on the amount of traffic that the control plane can process, effectively creating a policing mechanism for control plane traffic. When traffic exceeds the configured limits, CoPP can either drop or rate-limit the excess traffic to protect the control plane.
Key components of Control Plane Policing include:
Access Control Lists (ACLs): CoPP uses access control lists to define which types of traffic are allowed or denied access to the control plane. ACLs can be configured to match specific protocols, ports, or source/destination IP addresses.
Rate Limiting: CoPP enforces rate limits on control plane traffic. This ensures that the control plane only processes a specific amount of traffic within a given time frame.
Class Maps and Policy Maps: Control Plane Policing uses class maps and policy maps to define the traffic classification and policing actions. Class maps specify the criteria for identifying traffic, and policy maps define how the traffic is policed.
Logging and Monitoring: CoPP typically provides logging and monitoring capabilities so that network administrators can track control plane traffic and any actions taken by the CoPP feature.
Difference between conform-action, exceed-action and violate-action in control plane policing
In Control Plane Policing (CoPP), "conform-action," "exceed-action," and "violate-action" are actions that specify what should happen to different types of traffic based on whether they conform to, exceed, or violate the configured traffic rate limits. These actions are used to control and manage traffic that is being policed by CoPP.
Here's an explanation of each of these actions:
Conform-Action: This action is applied to traffic that conforms to the configured rate limits. In other words, when traffic falls within the permitted rate, it "conforms." The "conform-action" specifies what should happen to this traffic. Typically, conforming traffic is allowed to pass through without any additional restrictions. It's considered acceptable and within the defined policing parameters.
Exceed-Action: This action is applied to traffic that exceeds the configured rate limits but doesn't violate them. When traffic exceeds the specified rate but is still within the defined excess rate, the "exceed-action" determines what should happen. Common actions for exceeding traffic include dropping it or remarking the traffic to a lower priority or a different class of service. The idea is to handle this traffic less favorably than conforming traffic but not as harshly as violating traffic.
Violate-Action: This action is applied to traffic that violates the configured rate limits. When traffic exceeds the maximum rate allowed, it is considered a "violation." The "violate-action" specifies how to handle this traffic. Typically, violating traffic is either dropped or remarked to a lower priority or a different class of service. Violating traffic is generally the least desirable and may be associated with potential threats or attacks.
IPSLA
IPSLA, or Cisco IOS IP Service Level Agreements, is a feature in Cisco routers and switches that allows network administrators to measure, verify, and report on network performance.
ip sla 1
icmp-echo <target IP>
frequency 60
exit
ip sla schedule 1 life forever start-time now
show ip sla statistics 1
EEM
Cisco Embedded Event Manager (EEM) is a powerful and flexible subsystem available on Cisco devices that allows you to monitor events and take automated actions in response. EEM provides a scripting language that allows you to define policies to respond to events on the device.
Basic Concepts:
Event: An event is a significant occurrence or a state change that can trigger an action. Events can be related to system-level changes, interface status, SNMP traps, syslog messages, etc.
Policy: A policy is a set of rules that define what action should be taken when a specific event occurs.
Action: An action is a task or command that is executed when a policy is triggered by an event.
Answer: Cisco EEM, or Embedded Event Manager, is a feature embedded in Cisco devices that provides a scripting interface for monitoring events and taking automated actions in response to those events.
What are the key components of an EEM policy?
Answer: An EEM policy consists of an event, a trigger that specifies when the policy should be executed, and an action, which defines the tasks or commands to be performed when the event occurs.
Can you give an example of an event in EEM?
Answer: An example of an event is "event syslog pattern," where a policy is triggered based on a specific pattern in syslog messages.
How do you create a basic EEM policy?
Answer: Use the event manager applet configuration mode, define an event using the event command, and specify actions using the action command.
What is the purpose of the occurs keyword in an EEM policy?
Answer: The occurs keyword specifies how many times an event must occur before the associated actions are executed. For example, occurs 1 means the actions will be triggered on the first occurrence of the event.
Explain the use of the poll-interval keyword in an SNMP-related EEM event.
Answer: The poll-interval keyword sets the interval at which an SNMP query is repeated. It defines how often the device checks the specified SNMP variable for changes.
How can you view the existing EEM policies on a Cisco device?
Answer: Use the show event manager policy registered command to view a list of registered EEM policies.
What is the difference between an EEM applet and an EEM script?
Answer: An EEM applet is a simple and single-shot policy, while an EEM script is a more complex and reusable set of policies. An EEM script can contain multiple applets.
Can you explain the importance of error handling in EEM policies?
Answer: Error handling is crucial to ensure the robustness of EEM policies. Proper error handling helps prevent unintended consequences and ensures that the device behaves predictably even in the face of unexpected conditions.
How do you troubleshoot EEM policies that are not working as expected?
Answer: Use the show event manager policy registered and show event manager policy registered detail commands to check the status and details of registered policies. Additionally, examine the syslog messages for any errors or debug EEM events using the debug event manager action cli command.
NetFlow
NetFlow is a network protocol developed by Cisco Systems for collecting IP traffic information and monitoring network traffic flow. It provides a way to collect and analyze data about the traffic flowing through a router or switch, allowing network administrators to gain insights into network utilization, identify performance issues, and enhance security. NetFlow is widely used in various network environments, including enterprise networks, service provider networks, and data centers.
Here are the key concepts and components of NetFlow:
Flow: In NetFlow, a flow is a unidirectional sequence of packets that share common characteristics. It include source and destination IP addresses, source and destination port numbers, protocol, and the type of service. The flow is the basic unit of measurement in NetFlow.
Flow Record: A flow record is a collection of key fields that define a flow. It include source and destination IP addresses, source and destination port numbers, protocol, and other relevant information. Flow records are used to store information about individual flows.
Flow Exporter: A flow exporter is responsible for aggregating flow records and exporting them to a NetFlow collector for further analysis. The exporter formats the flow records and sends them to the collector using the NetFlow protocol (typically UDP).
Flow Collector: The flow collector is a system or software that receives and stores the flow records sent by flow exporters. It is responsible for processing and analyzing the collected data. NetFlow collectors can provide insights into network traffic patterns, usage, and potential issues.
Flow Sampler: In some cases, not all packets are included in the NetFlow data to reduce the processing load on routers and switches. Flow samplers are mechanisms used to sample a subset of packets to estimate the characteristics of the entire flow.
NetFlow Versions: There are different versions of the NetFlow protocol, such as NetFlow v5, v9, and IPFIX (which is similar to NetFlow v9 and standardized by the IETF). Each version may have additional features and improvements over the previous ones.
Netflow configuration example:
# Enable NetFlow on an interface
interface GigabitEthernet0/0
ip flow ingress
# Configure the NetFlow exporter
ip flow-export destination <collector-ip> <collector-port>