Vlan gets DHCP address but no internet

[Davit2005]

Seems really strange, have you tried pinging the different vLAN ip address from the CLI of the core switch.

 

The fact that clients are getting DHCP address indicates that routing is taking place.

[Blue_Cookeh]

Seems really strange, have you tried pinging the different vLAN ip address from the CLI of the core switch.

 

The fact that clients are getting DHCP address indicates that routing is taking place.

 

ip helper looks at broadcasts and acts as a middle man, it's a different way of working to routing. A device doesn't need to be able to route out of a VLAN for ip helper to do it's thing.

[TRS]

Woah, hang on ... I've think I've done it!

 

The port the router is on, is set to untagged (vlan 1) and not set to tagged on vlan 32 - theoretically that should mean it's untagged on vlan 1 and vlan 32, right? Apparently not! If I specifically "untag" the port for vlan 32 it all springs into life. Checking the config it still says ports untagged on vlan 1 but not on vlan 32 but it's all working. I'm guessing something a little strange with these HP switches.

 

Anyway, thanks for all the help guys ... now to find out what's wrong with that other switch .

 

Cheers

 

Tony

Edited July 22, 2016 by TRS

[Davit2005]

Jus found this on Cisco Press site which is pretty interesting

 

NOTE

 

The ip helper-address command forwards broadcast packets as a unicast to eight different UDP ports by default:

 

 

 

TFTP (port 69)

DNS (port 53)

Time service (port 37)

NetBIOS name server (port 137)

NetBIOS datagram server (port 138)

Boot Protocol (BOOTP) client and server datagrams (ports 67 and 68)

TACACS service (port 49)

Host Name Service (port 42)#

[Blue_Cookeh]

Woah, hang on ... I've think I've done it!

 

The port the router is on, is set to untagged (vlan 1) and not set to tagged on vlan 32 - theoretically that should mean it's untagged on vlan 1 and vlan 32, right? Apparently not! If I specifically "untag" the port for vlan 32 it all springs into life. Checking the config it still says ports untagged on vlan 1 but not on vlan 32 but it's all working. I'm guessing something a little strange with these HP switches.

 

Anyway, thanks for all the help guys ... now to find out what's wrong with that other switch .

 

Cheers

 

Tony

 

You might want to change around how you configure your link to the SchoolsBroadband router. If you go back and look at our switch config we specifically put the SB router on it's own VLAN and subnet so that what we do internally has 0 to do with the router so long as our core switch can route between VLANs.

[IrritableTech]

[edit]Sorry it seems I missed the second page on updates! Whoops Edited July 22, 2016 by IrritableTech

[IrritableTech]

You might want to change around how you configure your link to the SchoolsBroadband router. If you go back and look at our switch config we specifically put the SB router on it's own VLAN and subnet so that what we do internally has 0 to do with the router so long as our core switch can route between VLANs.

 

Yeah we've done the same - a small transport subnet with just the fortinet and our core switch. They fire all traffic at each other and each end sorts it out from there.

[TRS]

Thanks guys, I'll definitely look into that.

 

Cheers

 

Tony

[EricM_NetCtrl]

Are you still having issues with this?