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Vlan Overlaping

Answered Question
Mar 19th, 2012
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Hi



I am using Jermey's new CBT nuggets for CCNA and was making topology on gns3 all is going well but when I tried to make vlan interfaces its give me this error.







interface vlan 64



ip address 10.1.64.1 255.255.254.0



description "Voice Vlan"







interface vlan 66



ip address 10.1.66.1 255.255.254.0



description "Data Vlan"







interface vlan 68



ip address 10.1.68.1 255.255.254.0



description "Server Vlan"







interface vlan 69



ip address 10.1.69.1 255.255.254.0



description "Public WiFi Vlan"



ip address 10.1.70.1 255.255.254.0



% 10.1.70.0 overlaps with Vlan71     (Error)









interface vlan 70



ip address 10.1.70.1 255.255.254.0



description "Private LAB Vlan"



ip address 10.1.70.1 255.255.254.0



% 10.1.70.0 overlaps with Vlan71 (Error)







How can I resolve this problem. and I jeremey is doing the same on gns3 lab and he didnt get any error but I am getting this error please give me the solution.



thanks in advance .


Regards


Faisal

Correct Answer by glen.grant about 5 years 5 months ago

  If you use a /24 mask in your configs then you wouldn't have an issue.  The way you have it right now all your definitions cover 2 subnets  using  /23 mask .

Correct Answer by glen.grant about 5 years 5 months ago

  It's overlapping because you already have it configured on vlan 71 .  You can only have a range on a single SVI or routed port on the L3 switch.  vlan 71 with the mask you have covers .70 and .71  subnets .  If you already have vlan 71 configured with the same mask that's why it is complaining as it is overlapping.

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John Blakley Mon, 03/19/2012 - 11:09
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What does vlan 71 look like? I don't see it in the config...

fasi25300 Mon, 03/19/2012 - 11:48
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yes its a vlan 71 and I am trying to config this ip address on vlan 71 and 69 but it gives me error vlan overlapping I have attached complete SW1 configuration you can check if you find any solution .


many thanks in advance

Correct Answer
glen.grant Mon, 03/19/2012 - 12:18
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  It's overlapping because you already have it configured on vlan 71 .  You can only have a range on a single SVI or routed port on the L3 switch.  vlan 71 with the mask you have covers .70 and .71  subnets .  If you already have vlan 71 configured with the same mask that's why it is complaining as it is overlapping.

fasi25300 Mon, 03/19/2012 - 12:33
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Hi glen


thanks for your reply.


could you please guide me what mask should I use ad I watching the jeremey videos and I have done the same configuration but he didn't get any error only I got this error .

Correct Answer
glen.grant Mon, 03/19/2012 - 12:39
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  • Purple, 4500 points or more

  If you use a /24 mask in your configs then you wouldn't have an issue.  The way you have it right now all your definitions cover 2 subnets  using  /23 mask .

fasi25300 Mon, 03/19/2012 - 13:18
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thanks every one for your help and support


regards


Faisal

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