Cisco Answer of the Month – January 2012

Time to win a free book, just with an answer. Your knowledge has a value. You can use it to get a free book.

January 2012 Question:
XYZ Company has some partners’ computers on XYZ premises which are directly connected to XYZ network and they are communicating with a XYZ server. Network Engineer of XYZ already reserved 10.10.10.0/24 IP address block for partner connections. These partners do not need to communicate with each other.
For the first partner, network engineer created a VLAN and used 10.10.10.0/28 network. First partner started to use 10.10.10.3 and 10.10.10.4 for its computers.
For the second partner, network engineer created a VLAN and used 10.10.10.0/27 network. Second partner started to use 10.10.10.21 and 10.10.10.22 for its computers. Lowest IP on a network is the gateway. There is no firewall or NAT setting.
Does this setup work? Why or why not?

Rules:
You can send your answer as a comment to this post until the end of competition period (31st of January 2012 for this round). Please write your active e-mail address and do not add any personal information at this stage. We will reach to the winner over his/her e-mail. The qualified answer(s) will be chosen in first week of the next month. If there is more than one qualified answer, there will be sweepstake to find winner. Winner will have chance to choose one of the below books (brand new) as his /her prize. Winner and other answers will be published after the competition period. International participants are also welcome. Delivery times can vary depending on your country.

Prize:
One of the below books

or

Answer
Yes, it does. Because routing mechanism chooses most specific route when many of them exists. Most specific route for 10.10.10.3-4 is the first network and the second network for 10.10.10.21-22. However, this design is dead wrong.

Winner
This month’s winner is Arthur. You can find his answer below in comments. He preferred CVOICE 8.0 as his prize and confirmed that his book has been delivered.

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One Response to “Cisco Answer of the Month – January 2012”

  1. Arthur January 17th, 2012 at 2:03 pm

    This set up would work (for now) but its not very well designed as IP would start to overlap after a while. Both 10.10.10.0/28 (range = 10.10.10.0-15) and 10.10.10.0/27 (range = 10.10.10.0-31) contain IP addresses in the same ranges. So at this moment there are no conflicts as IP were assigned manually(maybe not but they dont overlap and only this matters), after a while however its highly likely there will be a problem.

    The way it should be designed is starting from the partner with highest amount of network nodes to the one with the lowest. Relating to this scenario 2nd partner should get 10.10.10.0/27 and 1st partner 10.10.10.32/28, in which case there will never be any IP conflicts.(allow for expansion too)

    Good question, hope its correct :-)

    Arthur

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