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How to do configure VLan on a 4006

Unanswered Question
May 8th, 2003
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I need Help ..

Actually our network is configured as is :

One Router 7120 , with ISL encapsulation

One Catalyst 3548 ,

One 3508

and 7 3524 and 3550 ..

MY question is .

We are very intersted of bying a Cat 4006 with superengine III , but I need to know if it will be necessery to Keep our Router 7120 or if we can use Layer 3 fonctions of the Supereng III in replacement ..

Thank you very much


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jolmo Thu, 05/08/2003 - 03:34
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I think if you only are using router 7120 as router-on-stick (just inter-VLAN routing, no WAN connections), such task can be done by the 4006. But take care of this:

The Catalyst 4006 switch with Supervisor Engine III does not support:

- Subinterfaces or the encapsulation keyword on Layer 3 Fast Ethernet or Gigabit Ethernet interfaces

- IPX routing and Appletalk routing

For more information about 4006 SupIII Layer 3 features and how to configure them take a look at:



mchabloz Thu, 05/08/2003 - 04:54
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Thank you for your answer but I would like to say that our 7120 is connected to our internet Provider .. and we have created on our routeur 20 VLAN , with ISL encapsulation ... And our Switch 3548 is directly linked on the router and .

Is it possible to reproduce the same thing only with a 4006 using the logical Vlan configuration on Layer 3 .. Can the 4006 cana work as a router , I mean can we connect the Internet Link directly to the 4006 ..

Thank you very much ..


Prashanth Krishnappa Thu, 05/08/2003 - 04:58
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We do not have WAN port support for Sup3/4. Check to see if your ISP provides ethernet/gigabit ethernet connections to customers. If they do and if you lease one, you can connect your 4006 directly to the ISP

mchabloz Thu, 05/08/2003 - 05:23
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Thank you , We have a ethernet connections .. ..

I've tryed to simulate our network .. I did this :

I ve got two 2500 router one , they are connected using DTE DCE Cable ..

One of the 2500 (1) is directly connected to the switch on a 10/100 Fastethernet port , I've configured a Ip address on it (On Layer 3) . The Cat 4006 Ip address ( on Vlan1 is also configured .. I've tried to do a traceroute from a laptop connected on the second 2500 . And then Ive got this result..


1 This the 1 Ip address on the 2500 (1)

2. This 4006 layer 3 Ip address

3. This the second Ip address(the link between 2500 and 4006 ) of the 2500 (1)



etc ..

Hop you undersund what I mean ..



bcbvale Thu, 05/08/2003 - 10:11
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You have a routing loop. The 4006 does not know that it has the interface directly connected on VLAN1. Check your routing. Your subnetting looks funny also. What are you using for the mask? Also, make sure that the VLAN1 interface is "up, up". What VLAN is on?


mchabloz Fri, 05/09/2003 - 06:39
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Their is no Vlan configured on Because this interface is a routed LAN to LAN directly connected to our Internet Provider .. All traffic must pass trought this interface .. .. .. Actually this Ip address is configured on the 48/10/100 module port 4/48 (and I ve configured "No switchport" (for Layer 3)) .


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