Today our class began on a somber note with some upsetting news from a leader whom I respect and admire. Unfortunately, due to an unknown set of circumstances this individual will no longer have the opportunity to continue in his current role as an IT leader. As he was discussing his situation I was reminded of two important things 1) the world of an IT change agent can be unpredictable if not volatile at times, and 2) a positive outlook on life, combined with some preparedness for financial change can help alleviate some frustration and stress. While this must certainly be a very challenging time of transition for him, I truly appreciate that he took the time to reflect on his situation and share some perceptive thoughts with our cohort. He reminded us that change agents should try to avoid being on the peripheral of the action; instead, they need to be diligent with connecting and communicating with key stakeholders, managers, and administrators etc. who are responsible for decision making. He also reminded us that the role of an IT leader is a very political position with a high level of risk. These are certainly factors that should be considered and reflected on when one pursues job opportunities in the ET/IT field.
Layer 3 Networking
To prepare for our task today, we connected the computers using the cat cables, USB keyboard and mouse. For video out we connected a molex to two VGA connections. Using the USB to serial adapter we connected the switch to the computer and confirmed our connection from yesterday. This process involved opening Options to check that the settings were correct, and logging in with the username (admin) and password (switch).
To unlock session types (FTP, Telnet and SSH) we used the commands: aaa authentication default local, write memory, then copy working certified. To create a new vlan (or a new network), we used the command: vlan 2.
To set the IP address for the new vlan we used the command: ip interface vlan-2 address 10.0.25.254 mask 255.255.0.0 vlan 2. This allowed us to subnet the class A network.
To set up a route (or direct traffic from our switch to the main switch) we used the command: ip static-route 0.0.0.0 mask 0.0.0.0 gateway 10.0.25.254 .
Next we opened a web browser and typed in our ip address: 192.168.1.254 to login to the graphical interface for the main switch.
To set up a layer 3 switch we needed to set up a static ip address: 192.168.25.68.
For our network we utilized a hub and spoke, or star topology with the head end housing the firewall and other shared services (ie. File server, email server etc.).
We configured our computer so it could communicate with the local switch (Figure 1. shows the IP address settings).
Figure 1
To see our local switch, we opened an Internet browser and used our IP address: 192.168.25.254 to access the web view graphical interface for the switch.
Mini Exercise: IP address and Subnet Mask
At first while we were trying to send a ping request between Sean’s computer and mine, we ran into some difficulty. Sean’s Firewall security McAfee would not allow us to access the ping. To trouble shoot, we ran the Linux operating system on another computer and then we were able to complete the exercise. Over the last few days I have learned how important trouble-shooting is in networking; it is important to only make one change at a time! Also, as Lyle mentioned yesterday, Google is my new best friend.
As we were testing the ping we figured out that we needed to set the address of the gateway for the computer running Linux. This was not required on the Mac operating system so we just deleted the router address. Upon review of the activity we noticed some anomalies with our connectivity between the Mac and the Linux system. This we learned was because these two operating systems use different TCP/IP stacks.
Overall, I feel that this exercise helped us to better understand subnetting and supernetting: when using a subnet mask less than 255.255.255.0 with a class c address, we are able to communicate with a greater number of devices. For example, a computer with the IP address: 192.168.0.10 and the subnet mask 255.255.252.0 can connect with any device that has an address from 192.168.0.1 - 192.168.3.254 . This allows for four times as many addresses compared to a computer using a standard class c subnet mask, which can only connect with 253 other devices using the IP address: 192.168.0.x.
When using a subnet mask greater than 255.255.0.0 with a class b address, we are able to communicate with fewer devices, although we could make more networks. For example, a computer with the IP address: 172.16.5.10 and the subnet mask 255.255.255.0 can only connect to a device with an address from 172.16.5.x. This is one quarter of the addresses one could use with a standard class b subnet, which could connect with 64,515 other devices.
I look forward to reviewing (in greater depth) some of the subnetting concepts tomorrow to solidify my understandings of these concepts.
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