just wanted to ask what measures I'll have to do regarding on my problem on CoreSwitch 6509. I have 12 vlans on layer 3 switch which has 48 ports, 4 ports per vlan and I have a backbone on vlan 10 and also used spanning tree mode. my question is that how will other vlans can connect with vlan 10 with has already connected to my ISP. your answers would be very much appreciated.


  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer.
    – Ron Maupin
    Aug 11, 2017 at 2:27

2 Answers 2


The layer-3 switch, assuming you have routing enabled with not blocking ACLs, will route between the VLANs. VLANs give you a complete layer-2 separation, and you must route traffic between VLANs if you need traffic from one VLAN to another.

  • Hi ron, I already tried it. for example i routed vlan20 and yet ther's no connection
    – Paolo
    Sep 14, 2016 at 2:18
  • You don't set a default route like that. You just enable routing. Manually configuring a route is unnecessary for directly connected networks, and it can cause problems.
    – Ron Maupin
    Sep 14, 2016 at 2:22
  • Sorr for that. Here's the deal, suppose I have vlan10 with 4 ports and vlan20 also with 4 ports, i already connected the backbone from router at vlan10, i just want to directly connect vlan20 to vlan10 without using any backbone comming from vlan10, so you said that i must not manually configure a route,so what should i do? thanks
    – Paolo
    Sep 14, 2016 at 2:26
  • I did not say you must manually configure a route. In fact, I said the opposite. A router, including a layer-3 switch with routing enabled, will automatically route between directly connected networks. You just need to make sure that routing is enabled on the switch. Edit your question to include you configuration so that we can quit playing 20 questions.
    – Ron Maupin
    Sep 14, 2016 at 2:30

You need to configure intervlan routing. On your 65xx configure interface vlan 10 and 20. Give them appropirate ip addresses. Vlan10 will have ip address from backbone subnet. For example, vlan 10 - subnet, vlan 20 - Set a default route towards backbone. If backbone router has, then set ip route Also you need to set route to vlan20 on your backbone router. So if your 6509 interface vlan10 ip address is, then set ip route 10 10.10.254 on your backbone router. If you want to connect to internet from vlan20, in that case you will meed to configure NAT on one of your devices.

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