Carlos Umanzor

Web Developer – Automation Specialist

Introducing one of my projects: LinkCrawler


Crawls a Site and gather information about Internal and External Links

HTMLUnit allows LinkCrawler to explore your site dinamically.

Saves report in HTML, EXCEL and JSON Format

Once the job is done, you can choose the right file format for you.

Intuitive User Interface with JavaFX

At version 3.5, the UI was moved from Swing to JavaFX to improve usability.

Works on Windows, Linux and Mac

It runs without problems on any Operating System with Java 7 or greater.

JavaFX Logo
Open Source
Maven project


Take a look at my latest post

BGP Example: 2 Networks with Layer 7 services

After a long reading, I was able to do a lab which contains some layer 7 services, also the networks are connected via BGP (due some packet tracer limitations, it will not perform as expected).

Here are the conditions of this lab:

  1. Both networks should be connected via a BGP mesh
  2. a DHCP service should be enabled in one of the networks
  3. Both networks should be have a DNS server (Due some packet tracer limitations, the DNS is lightly implemented)
  4. Port Security must be enabled with Sticky mac addresses
  5. Unused switch ports must be disabled.
Two networks connected via BGP, Layer 7 services are offered in each network

Take a look at the lab

Now here are some fun stuff that you can do:

  1. You can do nslookup on each networks (Packet tracer DNS support is limited to one network)
  2. DHCP Clients can be unplugged at any time. They will re-obtain the IP configuration back once they are connected to the switch again.
  3. Port Security is enabled on each Switch port. All current mac addresses are associated to each port permanently, as soon you connect a different end device with a different MAC address, the switch will shutdown the port.
  4.  At the Internet cloud, you can unplug cables and the routers will recalculate the best routes automatically, do it with the cable between BGP1 and BGP2 and you will see a lot of action.
  5. Layer 3 connectivity is available at both networks.

Console/Telnet pass: cisco

enable pass: class


Download the lab here.

Full Cisco Lab (Before Module 1 final test)

Take a look at the following lab:

Final Lab Example


  1. Network at Puntarenas (left) requires addresses for 58 hosts max, this is a startup company, so we will require additional addresses for a future expansion.
  2. Network at Alajuela (right) requires addresses for their current 22 hosts, there is no room for expansion. The clients are located in two different building sections.
  3. Provide an optimal IP scheme to supply both network and router point to point connections.
  4. All communication should work at full speed and full duplex.
  5. Telnet is not allowed for router/switch administration.
  6. SSH version 2 connections should be used.
  7. Connections to routers and switches should be terminated after a certain period of inactivity.

At the end of the example, clients at Alajuela can do and ping any resources on that network (and viceversa).

All routers and switches are using port security and SSH-only connections with extensive login control.

Additional services to configure:

  1. DNS Servers in both offices
  2. NTP and FTP server on Puntarenas Office
  3. All routers should pull date/time from the NTP service
  4. Routers must provide a DHCP service for their office clients.
  5. Port Security must be enables on Switches.
  6. Unused Switch ports must be turned off


First, we need to supply the biggest network, 58 hosts (2^6 = 64, 64 – 2, 62 valid hosts), We need 6 bits for hosts and we are going to take 2 for subnet

192.168.1.|00000000 /24 (original network)

Now we need to supply the network with 22 hosts (2^5 = 32 , 32-2, 30 valid hosts) We need 5 bits for hosts and 3 for subnet

Finally we need just 1 subnet for the point to point connection, we need two bits for hosts (2^2=4, 4-2, 2 valid hosts) and 3 more bits for subnets (that’s 6 in total for subnet), in short it will be:

Note: Pay special attention in how I’m handling the | symbol when taking bits for subnets.

IP assignation for Puntarenas

Device Name Interface IP/Mask
RPun G0/0 /
Serial 0/1/0 /
SWPun Vlan1 / eth0 /
DNS eth0 /
NTP-FTP eth0 /

IP assignation for Alajuela

Device Name Interface IP/Mask
RALA G0/0 /
Serial 0/1/0 /
SWALA Vlan1 / eth0 /
DNS eth0 /
Client1 to Client18 eth0 DHCP CLIENT

SSH Credentials

Device Username Password
RPun puntarenasrouter puntarenas
SWPun puntarenas puntarenas
RALA alajuelarouter alajuela
SWAla alajuela alajuela

Global Cisco settings

User EXEC Mode cisco (overridden when using SSH)
Privileged EXEC Mode class

Download lab from here.

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