One Router Single Switch Multiple VLan

[chennai.itsupport]

Hi Team,

We have one ISR2951 with LAN: 192.168.1.1 (dhcp server enable - 192.168.1.10 - 192.168.1.250)

And Cisco SG300 switch with

VLAN1 (default) 192.168.1.254

VLAN10 192.168.10.254

VLAN20 192.168.20.254

VLAN30 192.168.30.254

i made it in such a way that Port 1 is the trunk port 

and i tagged VLAN10,20and 30 to it.

Intervlan routing is happening meaning i can ping any machine connected to any of the vlan from the router and vice versa and also between VLANs

But only when i'm on VLAN1 i'm getting internet ..

and when i do dhcp relay on VLAN10,20 and 30 i'm not getting any ip from the router

i even try to enable ip helper on vlan10,20 and 30 but it says wrong ip address

and i create ip route for VLAN10,20 and 30 on the router

will it be possible for the router dhcp to relay dhcp to all the VLANs at the same time ...and get internet..

Physical connection is this way: 

Router LAN port connected to Switch trunk port 1 (VLAN1) and VLAN10,20,30 are tagged to VLAN1 and i want the router to relay dhcp on VLAN 10,20 n 30 also all the devices connected to the VLANs should get internet ....from the router...

Will this possible or i need additional ports on the router for VLAN10,20 and 30... pliz help

[chennai.itsupport]

Thank you danjone3 ..  the reason i ask is mainly due to ip roaming ...

We have 4 access point and i want each access point to have their own VLAN ... but when we put it that way .... wifi user when they roam from one AP to other their connection is reset as they move to different VLAN .... if it is possible for router to give out a single scope of dhcp to multiple VLAN i'm thinking may be user won't get disconnect 

We do have Ip roaming option on our Access point not sure if that option will fix the issue though...

[danjone3 · Accepted solution]

First, is there a legitimate reason you need to have each AP on a different VLAN?  The common practice is to have a separate VLAN for wireless traffic and to put all of the APs on that VLAN.  Large organizations with many wireless users may use multiple wireless VLANs, of course.  You can also create multiple wireless VLANs to segregate traffic, such as having a public VLAN for guests and a second VLAN for dedicated employees.  With Cisco APs, the VLAN is associated with the SSID and you broadcast multiple SSIDs for different purposes, with authentication configured to limit who can access the restricted SSIDs.  Take a look at your requirements and consider whether having each AP in a different subnet is required to meet your purposes, or whether you can meet those needs in a different manner, such as having multiple SSIDs.

As for roaming, are you using lightweight APs with a WLAN controller or autonomous APs?  If you're using LAPs with a WLC, you can allow roaming between subnets.  Essentially, when the wireless client hops to a new LAP in a different subnet, it retains its original IP and the traffic is tunneled to the original WLC if necessary and placed in the correct VLAN for that subnet.  I don't believe seamless layer 3 roaming is possible between autonomous APs in different subnets but wireless isn't my specialty, so don't take that as gospel.

[chennai.itsupport]

For now i believe associating VLAN with the SSID should work...

i did ran through cisco ip mobility doc..... 

[Richard Burts]

Thanks for the update. I am glad to hear that you are getting DHCP from the router and Internet for all the VLANs. As Danjone3 has explained you can not use the same DHCP scope for different VLANs. Each VLAN requires its own unique scope.

Depending on what your requirements are it could work well with the 4 networks that you appear to have configured. Or as Danjone3 has suggested if your requirements are to have everything in network 192.168.1.0 then it would be possible to subnet that network into 4 subnets and make each scope to be one of the subnets.

HTH

Rick

[LiangLiang95702]

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@chennai.itsupport wrote:

Thank you Rick for all the help.... now i get DHCP from the router and get internet to all the VLANs... :-)

One more doubt though:

how can i make the router to give out DHCP Scope : 192.168.1.0 to all the VLANs irrespective of the VLAN interface ip....

Thank you again for your help...

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May I know what have you configured to get the DHCP working and getting internet access to all Vlans?

I have the same issue at the moment.

TP Link VR1600R router with Cisco SG250-08 switch

[danjone3]

Your router config is abbreviated, so I can't see exactly what you're trying to do, but based on your description you have a single DHCP scope for 192.168.1.0/24 and you're trying to put hosts using that single subnet into different VLANs where the SVI's have IP addresses assigned from  different subnets.  Am I reading your post correctly?

[chennai.itsupport]

Danjone assigning the 192.168.1.0 address to all the VLANs is what a plan initially but i can't seem to make it work so i created a dhcp pool for VLAN10 (192.168.10.0) VLAN20 (192.168.20.0) and VLAN30 (192.168.30.0) on the router....