DHCP Relay Agent Configuration

[abdul.imran523]

Hi,

Please provide me guidance inorder to achieve the above task:

In My head office on Core switch :: so many vlan have already configured (up to 15 vlans )

My requirement is vlan 10 and its ip 172.x.x.x to be able to configure in brach network for only 3 pc ( in Branch network we have already two vlans )

i didnt configure anything in core switch

when i was try to configure the relay agent on branch switch ; unable to assign the following

#conf t

# int vlan 10

# ip dhcp relay enable

the above command give me the error;

please help me for the above commands

[Bilal Nawaz]

Hello, Please try using the 'ip helper-address x.x.x.x'

where x.x.x.x is your DHCP server IP address.

See here for more info: http://www.ciscopress.com/articles/article.asp?p=330807&seqNum=9

http://cisconet.com/tcpip/dhcp/107-how-to-use-ip-helper-address-to-connect-remote-dhcp-server.html

Hope this helps

Sent from Cisco Technical Support iPhone App

[abdul.imran523]

Can you  please tell me where can i configure this (Ip helper-address x.x.x.x ) i mean on branch side switch or router ?

[Bilal Nawaz]

You need to configure this on the interface wherever the default gateway will be for the clients/pc's.

Hope this helps

Sent from Cisco Technical Support iPhone App

[abdul.imran523]

Friend im not expert in cisco im just beginner,

suppose iam getting the ip from swtich :

Switch# conf t

          # int fa 0.1

          # ip helper-address X.X.X.X

Please provide me some commands

[Bilal Nawaz]

Apologies Mohd, I am not able to tell you the exact configuration since you havent told me where the default gateway will be for your PC's.

Is your 2960 switch just purely an access switch, is everything in the same vlan?

If i assume this, then your configuration will need to be on the 2800 series router, on the interface that connects to the 2960.

So on the 2800 you do this:

interface fa0/1

ip address x.x.x.x y.y.y.y

ip helper-address z.z.z.z

where z.z.z.z is your DHCP server.

I hope this explains a little better.

Please rate useful posts and remember to mark any solved questions as answered. Thank you.

[abdul.imran523]

Please see the below configuration of router: i have only two ports - 1 for isp and 2nd for switch

where as switch having 24 ports

interface FastEthernet0/0

ip address X.X.X.X   X.X.X.X

no ip redirects

no ip unreachables

no ip proxy-arp

ip virtual-reassembly

ip route-cache flow

duplex auto

speed auto

no mop enabled

!

interface FastEthernet0/1

description $ES_LAN$

no ip address

no ip redirects

no ip unreachables

no ip proxy-arp

ip virtual-reassembly

ip route-cache flow

ip tcp adjust-mss 1452

duplex auto

speed auto

no mop enabled

!

interface FastEthernet0/1.111

description Voice Vlan

encapsulation dot1Q 111

ip address 10.X.X.254 255.255.255.0

ip nat inside

ip virtual-reassembly

no cdp enable

!

interface FastEthernet0/1.211

description Data Vlan

encapsulation dot1Q 211

ip address 10.X.X.254 255.255.255.0

ip nat inside

ip virtual-reassembly

no cdp enable

[Bilal Nawaz]

Okay, thank you - this is what needs to be done on the 2800:

Conf t

!

interface FastEthernet0/1.111

ip helper-address x.x.x.x

!

interface FastEthernet0/1.211

ip helper-address x.x.x.x

Please ensure that you have connectivity from your router to the DHCP server for this to work.

Hope this helps.

Please rate useful posts and remember to mark any solved questions as answered. Thank you.