InterVlan Routing on Cisco

35 pts.
Tags:
Cisco 4506
Cisco VLAN
InterVLAN
Switches
Switching
VLAN
VLAN Routing
Hi, I have Ipbase Image on a Cisco 4506 switch and configured several vlans eg. 2,3,4 and each have ip addresses associated with them as given below. interface vlan 2 ip address 172.16.2.1 255.255.255.0 interface vlan 3 ip address 172.16.12.1 255.255.255.0 i have said ip routing but i do not see ip routing displayed in the config I want to be able to do intervlan routing between the 2 vlans. However when i do a show ip route command i do not see any connected vlans/routes. I am not using a routing protocol as both vlan's are configured on the same switch. Can anyone tell me where am i at fault and how i may correct it so i can get it to work? is it because i am not using a routing protocol?

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Do you have the command

ip routing

in the config? It doesn’t route unless you do. On some images this is not on by default.

Then look at the routing table

show ip route

and you should see the connected interfaces (your vlan interfaces) and it will then route between them by default if they are configured as the default gateway for devices in each vlan. you are correct that you do not need a routing protocol, as all the interfaces are on the same switch/router.

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  • Mannie1980
    Thanks for the reply. I do not see ip routing in the config. However if i do the command "no ip routing" this will appear in the config but as soon as i add the command "ip routing" i do not see anything in the config. I do not have any end devices connected. I am only configuring the 4506 switch with ip base image 12.2(50)SG1 and the switch is standalone. As said before no routing protocols configured. If i do show ip route there is no routes in the routing table. The connected interfaces that should be found through a given vlan do not appear in the route table. I would appreciate if you can explain to me what you mean by "it will then route between them by default if they are configured as the default gateway for devices in each vlan". This is a sample of what i have configured so that you can have an undestanding of what i have done: Before i did the below i created all the vlans in vlan database mode. interface Vlan2 description Data vlan ip address 172.16.2.2 255.255.255.0 no ip redirects standby 2 ip 172.16.2.1 standby 2 priority 120 standby 2 preempt delay minimum 90 standby 2 authentication xxx end interface Vlan3 description Server vlan ip address 172.16.12.2 255.255.255.0 no ip redirects standby 3 ip 192.168.12.1 standby 3 priority 120 standby 3 preempt delay minimum 90 standby 3 authentication xxx end
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  • BlankReg
    What I meant by “it will then route between them by default if they are configured as the default gateway for devices in each vlan” is that if a PC on a vlan uses the IP address of the 4506 as it's default gateway, then the 4506 will route the packet to the other VLAN with no other config required. I was just trying to say that you need to use the 4506 as the default gateway, and not another device. If there was another router, then you will need to add extra routes. You did do a 'no shut' on the VLAN interfaces, didn't you ? Also you don't need to create them in the vlan database any more, just do it at the normal config prompt, the syntax is the same as with the database. Just to check, you did do a 'status active' command for each vlan as well, to make sure they are activated ? I am not sure if this is still required, but probably good practice. Have a look at the 'show ip interface brief' command and check that it thinks these interfaces are up/up. Also have a look at the 'show vlan' command and check that the VLANs exist there as well. Try adding some physical interfaces, and connect a PC to them, one in each VLAN if possible. I seem to remember that it used to need an interface to be active for the VLAN to start to work, but that may just have been a software issue at the time. If any of these things fix it, please let us know. If not then please post the output from the commands listed above.
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  • Mannie1980
    Thanks for the reply. i have got it to work. as you have mentioned, what worked for me was connecting a couple of pcs to the physical interfaces, one in each vlan. These connection's activated the directly connected vlans which allowed me to route between them. I did not need to do a status active command for each vlan. I belive the status was active as i created the vlan in vlan database mode. Yes i did do a "no shut" on each interface after creating them. Thanks very much for your assistance. Appreciate it.
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  • BlankReg
    Really glad you got it working :-) Sorry if I was asking obvious questions, just wanted to be sure the basics had been covered ! Only the other day I forgot the 'no shut'' and then wondered why the vlan interface wasn't working. Daft old Reg ! You would expect it to work with the virtual interfaces alone, but for some reason it doesn't always do that. I think it depends on the hardware, so do, and some (like the 4500) do not. Best Regards, Reg
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  • Mannie1980
    Thanks for your help and thats fine you asked those questions. They are useful commands to check and make sure we have done the configuration correctly and there is nothing missing on our side. Best Regards, Mannie
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  • Snapper70
    Ah, one of the other gotchas you have to watch out for. A VLAN with no active interfaces may be considered down until you get at least ONE interface on the switch active - even connecting a cheap minihub is enough to do it.
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  • Genderhayes
    Multilayer Switch Feature Card MSFC on the Catalyst 6500/6000 series switches MSFC2 on the Catalyst 6500/6000 series switches Route Switch Feature Card RSFC on the Catalyst 5500/5000 series switches Route Switch Module SM on the Catalyst 5500/5000 series switches Route Switch Module (RSM) on the Catalyst 5500/5000 series switches Any Catalyst 5500/5000 or Catalyst 6500/6000 series switch running CatOS with a supported L3 card
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