ISP Handoff and VLAN configuration...

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Aug 16th, 2010
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I am completely new to the cisco configurations, but do have some experience configuring other routers and firewalls.

The problem I am having is configuring my cisco 2911 integrates services router to work with the IP info they provided me:

WAN BLOCK: X.X.254.108/30


LAN BLOCK: X.X.255.72/29


USABLE IP's: X.X.255.73-78


ISP SERIAL: X.X.254.109

In the setup I am working with, the Cisco 2911 will then connect to our firewall so it will be: ISP ethernet > CISCO 2911 GE0/1> CISCO 2911 GE0/2 > fiewall...

The ISP said I needed to "strip the VLAN" which I assumed the router should do on its own, however, I am unsure pf the IP address that I need to configure for the GE0/1 and GE0/2 interfaces... and if there is additional configuration necessary because the circut is comming to us over a metro ethernet VLAN (if thats what its called).



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Joe Clarke Mon, 08/16/2010 - 21:35
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To me it sounds like the ISP wants you to put  X.X.254.110 on your ethernet WAN interface.  On the LAN interface of the 2911 you can put any address in the X.X.255.73-78 range.

DanielMHussey Tue, 08/17/2010 - 17:37
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Some more info:

Not that this makes a huge difference but our usable IP's are 74-78, not 73-78

also, I was told by my ISP that our VLAN ID is 125 (I dont know if I need this in the configuration, I assume I don't) and that I need to 'strip the VLAN' which I am pretty sure is done by the router itself???

Finally- since I am new to this - I was wondering if I need to configure anything on the router that would incorporate the "VLAN" - I will try simply setting the WAN interface to the and the LAN interface to and see if that works tomorrow and see if that works.


Joe Clarke Tue, 08/17/2010 - 23:24
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I can't say for certain, but maybe they will give you an 802.1q trunk carying VLAN 125 that will contain the WAN subnet.  In that case, you would need to configure your interface for trunking with a dot1q subinterface that will have your WAN IP.


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