[c-nsp] DHCP problems trunked C2924 to C1841

Thu Aug 23 08:56:22 EDT 2007

Yes,

I have IP helper addresses on the vlan interfaces on the switch.

See this snippet:

interface VLAN2
 description vlan 2
 ip helper-address 172.23.0.1
 no ip directed-broadcast
 no ip route-cache
 shutdown
!

Only... the vlan interface stays down, but that makes sense, cause it is
not a L3 switch. Am wondering if that might be the problem... but such a
simple thing as a DHCP request should pass.. And... All the vlan's are
directly connected to the router, so a helper-address wouldn't even be
needed, as the requests should arrive over the trunk to the subinterface
on the C1841.

And yes, there is connectivity with static IP's, everything is working
on static IP's, but dhcp request don't arrive.

maarten

--
Network Engineer | eBay / Marktplaats.nl Randweg 25 | 8304 AS Emmeloord 
E-mail: mmoerman at ebay.com | Mobile: +31 6 55 1 222 47

-----Original Message-----
From: Simon [mailto:info at pitwood.org] 
Sent: Thursday, August 23, 2007 2:49 PM
To: 'Aaron Riemer'; Moerman, Maarten; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] DHCP problems trunked C2924 to C1841

Something else you should check is the IP-helper address will need to be
enabled if you are using one DHCP server

Simon

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Aaron Riemer
Sent: 23 August 2007 13:45
To: 'Moerman, Maarten'; cisco-nsp at puck.nether.net
Subject: Re: [c-nsp] DHCP problems trunked C2924 to C1841

Hi there, 

You mention you have a problem with DHCP. Does this mean that you have
connectivity when assigning static IP's to workstations on each
respective
vlan? 

If not I would check two things.  

1. The native vlan of the switch is vlan 1 (should be by default)
2. Check that all vlan's are allowed over the trunk.

Cheers,

Aaron.

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Moerman, Maarten
Sent: Thursday, 23 August 2007 7:54 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] DHCP problems trunked C2924 to C1841

Hello,

I've got a little problem on my home network regarding DHCP.

I have a C1841, and a C2924XL, which have a trunk between them.

I've setup 3 vlans, everything is working fine , however I can't get to
get DHCP working on the C1841. I'd like to have the first vlan dhcp
being served by a linux server (will be moved to the cisco in the
future), and the 2nd and third vlan dhcp being served by the C1841.

This is my config:

FastEthernet0/22 of the C2924XL is connected to FastEthernet0/0 of the
C1841.

ip dhcp excluded-address 172.24.0.2
ip dhcp excluded-address 172.24.0.3
!
ip dhcp pool buren
   network 172.24.0.0 255.255.255.0
   default-router 172.24.0.1
   dns-server 212.142.28.66
!
ip dhcp pool maarten
   network 172.25.0.0 255.255.255.0
   default-router 172.25.0.1
   dns-server 212.142.28.66
!
interface FastEthernet0/0.1
 encapsulation dot1Q 1 native
 ip address 172.23.0.1 255.255.255.0
 ip nat inside
 ip virtual-reassembly
 no ip route-cache
!
interface FastEthernet0/0.2
 encapsulation dot1Q 2
 ip address 172.24.0.1 255.255.255.0
 ip access-group 124 in
 ip nat inside
 ip virtual-reassembly
 no ip route-cache
!
interface FastEthernet0/0.3
encapsulation dot1Q 3
 ip address 172.25.0.1 255.255.255.0
 ip access-group 125 in
 ip helper-address 172.23.0.1
 ip nat inside
 ip virtual-reassembly
 no ip route-cache
!
access-list 124 deny   ip 172.24.0.0 0.0.0.255 172.23.0.0 0.0.0.255
access-list 124 deny   ip 172.24.0.0 0.0.0.255 172.25.0.0 0.0.0.255
access-list 124 permit ip 172.24.0.0 0.0.0.255 any
access-list 125 deny   ip 172.25.0.0 0.0.0.255 172.23.0.0 0.0.0.255
access-list 125 deny   ip 172.25.0.0 0.0.0.255 172.24.0.0 0.0.0.255
access-list 125 permit ip 172.25.0.0 0.0.0.255 any

And of course a lot of other things which aren't interesting for this
audience. ACL's arent' the problem I think, because with debugging I
don't see them hitting the ACL's.

This is my C2924Xl config:

interface VLAN1
 ip address 172.23.0.3 255.255.255.0
 no ip directed-broadcast
 no ip route-cache
!
interface VLAN2
 description vlan 2
 ip helper-address 172.23.0.1
 no ip directed-broadcast
 no ip route-cache
 shutdown
!
interface VLAN3
 description vlan 3
 ip helper-address 172.25.0.1
 no ip directed-broadcast
 no ip route-cache
 shutdown
!
interface FastEthernet0/21
 switchport access vlan 2
 spanning-tree portfast
!
interface FastEthernet0/22
 switchport trunk encapsulation dot1q
 switchport mode trunk
end

If I set all the debugging info there is, I cannot see any request for
vlan2 + 3 passing by.

Anyone have a clue?

--
Network Engineer | eBay / Marktplaats.nl Randweg 25 | 8304 AS Emmeloord 
E-mail: mmoerman at ebay.com | Mobile: +31 6 55 1 222 47

_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/

_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/