router dhcp problem

[Jangelides]

Hi guys, currently learning CCNA. Stuck with a small probem. I have a 1760 Router that I have configured as a DHCP server to the VLAN's on my switch. I have followed all the instructions that I have found but unfortunately the switch is just not getting assigned the ip addresses.  Can anyone help me please.

Here is my router config

Current configuration : 6971 bytes
!
version 12.4
service timestamps debug datetime msec
service timestamps log datetime msec
no service password-encryption
!
hostname SunrayR
!
boot-start-marker
boot-end-marker
!
!
no aaa new-model
!
resource policy
!
mmi polling-interval 60
no mmi auto-configure
no mmi pvc
mmi snmp-timeout 180
ip cef
!        
!
no ip dhcp use vrf connected
ip dhcp excluded-address 192.168.20.1
ip dhcp excluded-address 192.168.30.1
!
ip dhcp pool LAN10
   network 192.168.10.0 255.255.255.0
   default-router 192.168.10.1
!
ip dhcp pool LAN20
   network 192.168.20.0 255.255.255.0
   default-router 192.168.20.1
!
ip dhcp pool LAN30
   network 192.168.30.0 255.255.255.0
   default-router 192.168.30.1
!
!
!
!
!
interface FastEthernet0/0
 no ip address
 speed 100
 full-duplex
!
interface FastEthernet0/0.10
 encapsulation dot1Q 10
 ip address 192.168.10.1 255.255.255.0
 no snmp trap link-status
!
interface FastEthernet0/0.20
 encapsulation dot1Q 20
 ip address 192.168.20.1 255.255.255.0
 no snmp trap link-status
!
interface FastEthernet0/0.30
 encapsulation dot1Q 30
 ip address 192.168.30.1 255.255.255.0
 no snmp trap link-status
!
interface Serial0/0
 no ip address
 shutdown
!
interface Ethernet1/0
 no ip address
 shutdown
 half-duplex
!
!
!
no ip http server
no ip http secure-server
!
!
!
control-plane
!
!
!
!
!
!
!
!
!
line con 0
 exec-timeout 0 0
 password ********
 logging synchronous
 login
line aux 0
line vty 0 4
 exec-timeout 0 0
 password ********
 logging synchronous
 login
 transport input ssh
line vty 5 15
 exec-timeout 0 0
 password ********
 logging synchronous
 login
 transport input ssh
!
end

Special thanks in advance.

[acampbell]

Hi,

If I understand your issue poperly.
You are talking about the switch itself
not gaining an ip address.

If the switch is in default it will have NO
KNOWLEDGE of any vlans other than VLAN 1, therfore it will
be sending its DHCP discover through vlan 1

Try adding a dhcp pool for vlan 1 and add a dotq interface
for vlan 1

!
!
ip dhcp excluded-address 192.168.10.1
! YOU HAVE MISSED THIS LINE IN YOUR CONFIG FOR VLAN 10
!
!
!
ip dhcp excluded-address 192.168.1.1
ip dhcp pool LAN1
   network 192.168.10.0 255.255.255.0
   default-router 192.168.1.1
!
!
interface FastEthernet0/0.1
 encapsulation dot1Q 1 native
 ip address 192.168.1.1 255.255.255.0
 no snmp trap link-status
!
!

In the real world most network people allocate 
fixed IP addresses to their lan switches as they
are an intgeral part of our data neworks and
we dont want to depend on a network service to allow
us to gain access to manage of fault on the swiches

Hope this helps
Regards
Alex
  

[Jangelides]

Thank you for your advice. I will give that a go and let you know if it worked.

[johnlloyd_13]

hi,

could you post your switch config?

make sure you've enabled a trunk port and an ip default-gateway configured.

[Jangelides]

Here is my switch config - 

Current configuration:
!
version 12.0
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname SW1
!
enable secret 5 $1$AK3s$K4.bPaZ8QKyxnLYGtAvke.
!
!
!
!
!
!
ip subnet-zero
!
!
!
interface FastEthernet0/1
 duplex full
 speed 100
 switchport trunk encapsulation dot1q
!
interface FastEthernet0/2
 duplex full
 speed 100
 switchport access vlan 10
!
interface FastEthernet0/3
 duplex full
 speed 100
 switchport access vlan 10
!
interface FastEthernet0/4

 duplex full
 speed 100
 switchport access vlan 10
!
interface FastEthernet0/5

 duplex full
 speed 100
 switchport access vlan 20
!
interface FastEthernet0/6

duplex full
 speed 100
 switchport access vlan 20
!
interface FastEthernet0/7

duplex full
 speed 100
 switchport access vlan 20
!
interface FastEthernet0/8

duplex full
 speed 100
 switchport access vlan 30
!         
interface FastEthernet0/9

duplex full
 speed 100
 switchport access vlan 30
!
interface FastEthernet0/10

duplex full
 speed 100
 switchport access vlan 30
!
interface FastEthernet0/11
!
interface FastEthernet0/12
!
interface FastEthernet0/13
!
interface FastEthernet0/14
!
interface FastEthernet0/15
!
interface FastEthernet0/16
!
interface FastEthernet0/17
!
interface FastEthernet0/18
!
interface FastEthernet0/19
!
interface FastEthernet0/20
!
interface FastEthernet0/21
!
interface FastEthernet0/22
!
interface FastEthernet0/23
!
interface FastEthernet0/24
!
interface FastEthernet0/25
!
interface FastEthernet0/26
!
interface FastEthernet0/27
!
interface FastEthernet0/28
!
interface FastEthernet0/29
!
interface FastEthernet0/30
!
interface FastEthernet0/31
!         
interface FastEthernet0/32
!
interface FastEthernet0/33
!
interface FastEthernet0/34
!
interface FastEthernet0/35
!
interface FastEthernet0/36
!
interface FastEthernet0/37
!
interface FastEthernet0/38
!
interface FastEthernet0/39
!
interface FastEthernet0/40
!
interface FastEthernet0/41
!
interface FastEthernet0/42
!
interface FastEthernet0/43
!
interface FastEthernet0/44
!
interface FastEthernet0/45
!
interface FastEthernet0/46
!
interface FastEthernet0/47
!
interface FastEthernet0/48
!
interface GigabitEthernet0/1
 switchport trunk encapsulation dot1q
 switchport mode trunk
!
interface GigabitEthernet0/2
 switchport trunk encapsulation dot1q
 switchport mode trunk
!
interface VLAN1
 no ip directed-broadcast
 no ip route-cache
!         
interface VLAN10
 no ip directed-broadcast
 no ip route-cache
 shutdown
!
interface VLAN20
 no ip directed-broadcast
 no ip route-cache
 shutdown

!

interface VLAN30
 no ip directed-broadcast
 no ip route-cache
 shutdown
!
ip default-gateway 192.168.1.1
!
line con 0
 password ********
 logging synchronous
 login
 transport input none
 stopbits 1
line vty 0 4
 exec-timeout 0 0
 password ********
 logging synchronous
 login    
 transport input telnet
line vty 5 15
 exec-timeout 0 0
 password ********
 logging synchronous
 login
 transport input telnet
!
end

[Jangelides]

Hi Alex, thank you for your time and your advice, I added your suggestions to the router but still no joy, the switch is still not picking up a valid ip address. 

[Ji-Won Park]

Hi,

You need to configure "ip helper-address" under the SVIs on the switch.

Switch#

conf t

int vlan 10

ip helper-address 192.168.10.1

int vl 20

ip helper-address 192.168.20.1

int vl 30

ip helper-address 192.168.30.1

[Jangelides]

Thank you, i have added that but still no change.  This is really getting annoying!!

[Jon Marshall]

You don't need "ip helper-address ..." commands as you are using subinterfaces on the router.

Can you clarify exactly what the problem is ie. -

1) are clients connected to the switch not getting IPs

or

2) is it the switch itself not getting an IP

which port on your switch connects to the router ?

Jon

[Jangelides]

I thought that was strange to add the IP helper-address command as my switch is not layer 3. The client device, my laptop, is not picking up an ip address. As for the switch picking up an address, I'm not sure.I did give my vlan 1 a static IP address of 192.168.1.2 on my switch. Port 1 in my switch which is in native vlan 1 is connected to fa0/0 on the router.

[Jon Marshall]

Okay, lets forget about the switch and concentrate on the clients.

Can you post from the switch -

1) "sh int trunk" from the switch

2) "sh vlan brief"

Jon

[Jangelides]

SW1#show int fa0/1 switchport 
Name: Fa0/1
Switchport: Enabled
Administrative mode: static access
Operational Mode: static access
Administrative Trunking Encapsulation: dot1q
Operational Trunking Encapsulation: dot1q
Negotiation of Trunking: Disabled
Access Mode VLAN: 1 (default)
Trunking Native Mode VLAN: 1 (default)
Trunking VLANs Enabled: NONE
Pruning VLANs Enabled: NONE

Priority for untagged frames: 0
Override vlan tag priority: FALSE
Voice VLAN: none
Appliance trust: none
Self Loopback: No

SW1#show vlan br 
VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1, Fa0/4, Fa0/5, Fa0/6,
                                                Fa0/7, Fa0/8, Fa0/9, Fa0/10,
                                                Fa0/11, Fa0/12, Fa0/13, Fa0/14,
                                                Fa0/15, Fa0/16, Fa0/17, Fa0/18,
                                                Fa0/19, Fa0/20, Fa0/21, Fa0/22,
                                                Fa0/23, Fa0/24, Fa0/25, Fa0/26,
                                                Fa0/27, Fa0/28, Fa0/29, Fa0/30,
                                                Fa0/31, Fa0/32, Fa0/33, Fa0/34,
                                                Fa0/35, Fa0/36, Fa0/37, Fa0/38,
                                                Fa0/39, Fa0/40, Fa0/41, Fa0/42,
                                                Fa0/43, Fa0/44, Fa0/45, Fa0/46,
                                                Fa0/47, Fa0/48
10   VLAN0010                         active    Fa0/2, Fa0/3
20   VLAN0020                         active    
30   VLAN0030                         active    
1002 fddi-default                     active    
1003 token-ring-default               active    
1004 fddinet-default                  active    
1005 trnet-default                    active  

[Jon Marshall · Accepted solution]

Can you add this to your switch config -

int fa0/1

switchport mode trunk 

Jon

[Jangelides]

Well not sure what happened Jon but as you can see in the above post, fa0/1 on the switch is configured as a trunk link. But as you requested, I retyped the command:

int fa0/1

switchport mode trunk

and Voilà. It's all come up.  Thank you so much for all your help.  Very very very much appreciated.  

[Jon Marshall]

No problem.

Just to clarify though, if you look at the switch config you posted it wasn't configured as a trunk because you had just entered the encapsulation type and not the actual mode of the port.

If you also look at the output of the "sh int ...." command you posted you can see that it was acting as an access port.

So it was only after you entered the "switchport mode trunk" command that it changed to a trunk link.

Jon