Ethernet Switches & Routers

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Contributor
Posts: 50
Registered: ‎01-07-2011

DHCP Server

I am trying to configure a DHCP sever on a FCX running layer 2 software and the "ip dhcp-server" command is not available. I have checked the configuration guide and this feature is supported...

Any ideas?

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: DHCP Server

Hi Chris,

     What version of code is the FCX running.  This function was added in 7.2.00.  Please make sure you are running the latest 7.2 code.

Thanks

Michael.

Contributor
Posts: 50
Registered: ‎01-07-2011

Re: DHCP Server

Michael,

Thank you for the reply. I am running 7.2....Booted using the layer 2 code because I saw in the documentation that the DHCP server is not supported in the base layer 3 image.

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: DHCP Server

hmm, ok I have not tested this - my only guess would be the switch maybe setup to obtain a dhcp address for itself or have no ipaddress assigned to the switch.

Could you post your config?

Contributor
Posts: 50
Registered: ‎01-07-2011

Re: DHCP Server

Does anyone know how you can bind a DHCP scope configured on a Brocade FastIron switch to a certain VLAN?

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: DHCP Server

Hi Chris,

     I cannot see any way to apply a scope to a specific VALN.

     Are you saying that VLAN X does not receive a DHCP lease or what all VLANs are recevice leases and you want to appliy to only one VLAN?

     One way locking down to one VLAN might be a ACL.  Need more infoprmation sorry.

Thanks

Michael.

Contributor
Posts: 54
Registered: ‎01-27-2010

Re: DHCP Server

Interestingly, there's no "base layer 3" code for the FCX. 

The Layer 3 ("R"outing) code supports all features except BGP4, which requires an "ADV" software license but runs from the same image, most recently FCXR07200a.bin.  So all FCX code, L2 & L3, now supports DHCP server.

Contributor
Posts: 54
Registered: ‎01-27-2010

Re: DHCP Server

At least on an FCX running 7.2.00a Layer 3, the DHCP server seems pretty smart about VLANs and subnets.  My laptop gets an address when connected to a port that's in a vlan which has a router-interface with an IP in the DHCP pool subnet.  It does NOT get an address when in a VLAN with a router-interface in a different subnet.

EXAMPLE

pool is 2.2.2.0/24

vlan 2

  untagged e 1/1/2

  router-interface ve 2

interface ve 2

  ip address 2.2.2.1/24

vlan 3
  untagged e 1/1/3
  router-interface ve 3
interface ve 3
  ip address 3.3.3.1/24 (different subnet than DHCP pool)

Port 2 has DHCP.

Port 3 doesn't.

So with Layer 3 code, one way to limit DHCP to a specific VLAN is to make sure that other VLANs are assigned IPs in subnets different from the DHCP pool. Or if you create another pool for the second subnet, DHCP will work correctly on both subnets.  You'd think they planned it ;-)

NOTE:  When testing, if you move a device between VLANs/pools, end the lease using clear ip dhcp-server binding A.B.C.D so it will issue a different IP to the MAC that moved.

Contributor
Posts: 50
Registered: ‎01-07-2011

Re: DHCP Server

What I am trying to do is configure the DHCP server on and FWS with multipule VLANs. I can't get the switch to issue IP addresses to devices in a VLAN other than VLAN 1.

Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: DHCP Server

This may work for you - though I normally use this layer 3 VLANs.  Give it a try.

Configuring an IP helper address

To forward a client broadcast request for a UDP application when the client and server are on

different networks, you must configure a helper address on the interface connected to the client.

Specify the server IP address or the subnet directed broadcast address of the IP subnet the server is in as the helper address.

You can configure up to 16 helper addresses on each interface. You can configure a helper

address on an Ethernet port or a virtual interface.

To configure a helper address on interface 2 on chassis module 1, enter the following commands.

FastIronconfig)# interface ethernet 1/2

FastIron(config-if-1/2)# ip helper-address 1 207.95.7.6

The commands in this example change the CLI to the configuration level for port 1/2, then add a helper address for server 207.95.7.6 to the port. If the port receives a client request for any of the applications that the Layer 3 Switch is enabled to forward, the Layer 3 Switch forwards the client request to the server.

Syntax: ip helper-address

<num> <ip-addr>

The <num> parameter specifies the helper address number and can be from 1 through 16.

The <ip-addr> command specifies the server IP address or the subnet directed broadcast address

of the IP subnet the server is in.

You would configure this in the VLAN

Thanks

Michael.

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