Saturday, January 28, 2023

A10 SLB - How to configure a Layer 4 Virtual Server


Here is a step-by-step guide on how to configure a Layer 4 virtual server on an A10 Server Load Balancing (SLB) appliance using the CLI command and GUI.


Configure a Layer 4 Virtual Server


Step 1. Enter Configuration Mode

Enter configuration mode by typing the following command:
configure

Step 2. Define Real Servers (nodes/pool members)

Must include object name, IP address or DNS name & port.
A Layer 3 default Health Check will be applied to the Real Server IP addresses.
A Layer 4 default Health Check will be applied to match the ‘port 80 tcp’ command.

  • CLI
slb server realserver1 10.1.20.11
 port 80 tcp
slb server realserver2 10.1.20.12
 port 80 tcp
slb server realserver3 10.1.20.13
 port 80 tcp
 exit
 exit

  • GUI


Step 3. Create a Service Group (pool/server farm)

Group of servers that fulfill a service.
Load balancing algorithm applied here. Round Robin is used by default.

  • CLI
slb service-group webapp1_80 tcp
   member realserver1 80
   member realserver2 80
   member realserver3 80
   exit
   exit

  • GUI


Step 3-A (Optional). Change the Load Balancing algorithm

Change the Load Balancing algorithm method if needed.

  • CLI
    Here are some of the common load balancing methods available on the A10:
  1. Round Robin: This method distributes incoming traffic equally among all available real servers in a sequential order. It is a simple and straightforward method and is commonly used as the default method.
  2. Least Connections: This method distributes incoming traffic to the real server with the fewest number of active connections. It is useful in scenarios where the real servers have different processing capacities.
  3. Weighted Round Robin: This method distributes incoming traffic to the real servers based on their weight. You can assign a weight value to each real server, and the traffic will be distributed based on the ratio of their weights. This method is useful when you want to control the proportion of traffic sent to each real server.
  4. Source IP Hash: This method distributes incoming traffic based on the source IP address of the incoming request. It ensures that the same source IP address is always sent to the same real server. This method is useful in scenarios where the client needs to maintain persistent connections to the same real server.
  5. Destination IP Hash: This method distributes incoming traffic based on the destination IP address of the incoming request. It ensures that requests for the same destination IP address are always sent to the same real server. This method is useful in scenarios where you want to balance the load based on the destination of the incoming request.


You can specify the load balancing method by using the method or lb-method command followed by the method name. For example, to set the load balancing method to least-connection or least-connections, you would use the following command:

method round-robin
method least-connection
method weighted-rr
method dst-ip-hash
method fastest-response

slb service-group webapp1_80 tcp
	method least-connection

---
lb-method round-robin
lb-method least-connections
lb-method weighted-round-robin
lb-method source-ip-hash
lb-method destination-ip-hash

slb service-group webapp1_80 tcp
	lb-method least-connections


※ Note: The method command is typically found in newer software versions of the A10 Thunder series of load balancers, such as the TH3030S.

The lb-method command, on the other hand, is typically found in older software versions of A10 load balancers.

  • GUI

Step 4. Create Source NAT Pool

  • CLI
ip nat pool webapp_srcnat 10.1.20.240 10.1.20.241 netmask /24

  • GUI


Step 5. Create Virtual Server (vserver/vip/virtual address)

Must include object name, IP address and port (vport).
A virtual server is the combination of the real servers and ACOS device, which together appear as a single server to the client.

  • CLI
slb virtual-server webapp1 10.1.10.11
 port 80 tcp
  source-nat pool webapp_srcnat
  service-group webapp1_80
  exit
  exit
  exit

  • GUI


Step 6. Exit Configuration Mode and Save Configuration

To exit configuration mode, use the following command:
end

To save the configuration, use the following command:
write memory

Step 7. Check the Virtual Server status

To check the status of the virtual server, use the following command:
show slb virtual-server bind



Step 8. Test service access on a web browser

To test service access, open a web browser and enter the virtual IP address ‘10.1.10.11’ in the address bar. You should be able to access the service hosted on the real servers.

※ Note: The commands and syntax used in this guide may vary depending on the version and model of your A10 Server Load Balancer. It is recommended to consult the official documentation for the exact commands and syntax for your specific device.

References

(240) A10- Configure a Layer 4 Virtual Server in 4 Steps - YouTube

Links

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Saturday, January 21, 2023

Procrastination No More - Proven Techniques to Boost Productivity and Get Things Done


If you’re struggling with procrastination, you’re not alone. Many of us have trouble getting started on tasks, despite knowing we need to do them. To help you overcome this common challenge, here are 10 tips for avoiding procrastination:

  1. Setting clear and specific goals: Break your tasks into smaller, more manageable chunks and set clear deadlines for yourself.

  2. Prioritizing tasks: Identify the Most Important Tasks (MIT) and focus on them first.

  3. Eliminating distractions: Remove anything that might distract you while you work, such as your phone or social media.

  4. Using a timer: Set a timer for a specific amount of time and work on a task until the timer goes off.

  5. Using the Pomodoro Technique: Break your work into 25-minute intervals, with short breaks in between.

  6. Using the Eisenhower matrix: Prioritize your tasks by urgency and importance.

  7. Using positive self-talk: Encourage yourself with positive affirmations and remind yourself of the benefits of completing the task.

  8. Using rewards: Reward yourself for completing tasks to motivate yourself.

  9. Using accountability: Share your goals and progress with others to hold yourself accountable.

  10. Taking care of yourself: Make sure to get enough sleep, exercise, and eat well to help keep your energy levels up.

Procrastination can be a tough habit to break, but by implementing these strategies, you’ll be on your way to becoming more productive and achieving your goals. Remember, the key is to stay focused and motivated, and to not let yourself get bogged down by distractions.


References

Pomodoro Technique - Wikipedia
Eisenhower Matrix | Prioritization Framework | Definition and Examples

Links

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Thursday, January 19, 2023

Extreme Switch - How to configure NTP and SNTP in EXOS


Network Time Protocol (NTP) is a widely used method for synchronizing time across devices on a network. Here are two methods for configuring time synchronization on an EXOS switch.


NTP (Network Time Protocol)

The feature of NTP was added to EXOS in version 12.7. From version 12.7 to 15.4, an additional component called NTP XMOD was needed to configure and use the feature. However, starting from EXOS version 15.5, NTP is already included in the standard EXOS image, so there is no need for the NTP XMOD component.

Step 1. Configure the following commands

configure ntp server add clock.sjc.he.net vr VR-Default
configure ntp server add time.google.com vr VR-Default
enable ntp vr VR-Default
enable ntp vlan v100

  • Command syntax
configure ntp [server | peer] add [ip_address | host_name] {key keyid} {option [burst | initial-burst]} 
{{vr} vr_name}

If no VR is specified, VR-Default will be used by default.

Step 2. Check NTP association with NTP servers

EXOS# show ntp association
VR Name               Remote                    Reference ID    St Poll Reach Delay   Offset   Disp
===================== ========================= =============== == ==== ===== ======= ======== =======
VR-Default            *!time.google.com         .GOOG.          1  1024 377   0.05095 -0.00021 0.12369
VR-Default            .!clock.sjc.he.net        162.159.200.123 4  1024 377   0.01360 +0.00061 0.13824

St(ratum)   : Distance from the reference clock
Disp(ersion): Maximum offset error of clock
Flags       : (*) System Peer, (.) Candidate, (#) Short List, (!) Configured

Step 3. Check current time

Check the current time with the following command.

EXOS # show time
Thu Jan 19 19:37:07 PST(UTC-480) 2023




SNTP (Simple Network Time Protocol)

SNTP (Simple Network Time Protocol) and NTP (Network Time Protocol) are both used for synchronizing time across devices on a network. NTP is a more robust and accurate protocol, while SNTP is a simplified version that is less accurate but also less resource-intensive. SNTP is typically used for devices with limited processing power, while NTP is used for more critical systems that require precise time synchronization.

Step 1. Configure the following commands

configure sntp-client primary clock.sjc.he.net vr VR-Default
configure sntp-client secondary time.google.com vr VR-Default
configure sntp-client broadcast vr VR-Default

Please change the server name or IP address if you have preferred hosts.

  • Command syntax
configure sntp-client [primary | secondary] host-name-or-ip {vr vr_name}

Queries are first sent to the primary server. If the primary server does not respond within 1 second, or if it is not synchronized, the switch queries the second server. If the switch cannot obtain the time, it restarts the query process. Otherwise, the switch waits for the sntp-client update-interval before querying again.

(Optional) Configure the update interval

Change the update interval with the following command if required.

EXOS # configure sntp-client update-interval ?
  <update-interval>  update interval in seconds [16-16284]. (Default 64)

The following example configures a primary NTP server:

configure sntp-client primary 216.218.254.202

The following example configures the primary NTP server to use the management virtual router VR- Mgmt:

configure sntp-client primary 216.218.254.202 vr VR-Mgmt

Step 2. Check SNTP validation with NTP servers

EXOS# show sntp-client
SNTP client is enabled
SNTP time is valid
Primary server:clock.sjc.he.net  VR-Default
Secondary server:time.google.com  VR-Default
Broadcasts: VR-Default
Query interval:64
Last valid SNTP update: From server:clock.sjc.he.net, on Thu Jan 19 19:42:38 2023

SNTPC Statistics:
 Packets transmitted:
  to primary server:            1
  to secondary server:          0
 Packets received with valid time:
  from Primary server:          1
  from Secondary server:        0
  from Broadcast server:        0
 Packets received without valid time:
  from Primary server:          0
  from Secondary server:        0
  from Broadcast server:        0
 Replies not received to requests:
  from Primary server:          0
  from Secondary server:        0

Step 3. Check current time

Check the current time with the following command.

EXOS # show time
Thu Jan 19 19:37:07 PST(UTC-480) 2023

You may use the ‘show switch’ command to check the current time.

EXOS# show switch

SysName:          X440G2-12p-10G4
SysLocation:      Address
SysContact:       [email protected], +1 888 257 3000
System MAC:       00:04:96:9A:12:XX
System Type:      X440G2-12p-10G4

SysHealth check:  Enabled (Normal)
Recovery Mode:    All
System Watchdog:  Enabled

Current Time:     Thu Jan 19 19:45:53 2023
Timezone:         [Auto DST Enabled] GMT Offset: -480 minutes, name is PST.
                  DST of 60 minutes is currently not in effect, name is not set.
                  DST begins every second Sunday March at 2:00
                  DST ends every first Sunday November at 2:00




Is it possible to configure NTP and SNTP simultaneously in EXOS?

No. It is not possible to configure both SNTP and NTP simultaneously on a device. To enable NTP or switch to using the device as an NTP server, it may be necessary to first disable SNTP.

EXOS# enable ntp
EXOS# enable sntp-client
Error: NTP is already enabled. To use SNTP, please disable NTP at first and then enable SNTP.

EXOS# enable sntp-client
EXOS# enable ntp
Error: SNTP is already enabled. To use NTP, please disable SNTP at first and then enable NTP.

References

Q A: How to Configure NTP on EXOS switch? | Extreme Portal

Links

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