10-13-2011 05:08 AM
We have a Brocade FCX switch/router and are setting an ip helper-address on a ve interface to use our DHCP server on another VLAN than the DHCP request comes from. This works as expected when the DHCP server replies with an IP for the client other than 192.168.X.X. As soon as the DHCP server wants to assign the asking DHCP client an IP from the 192.168.X.X network the reply is not forwarded by the FCX to the client (I see the answer going out of the server with tcpdump). What can we do to get this working?
Thanks a lot for your help!
10-13-2011 12:44 PM
What versions of code are you runing please (do a 'show version').
If the subnet if anthing else apart fromt he 192.168.x.x e.g. 172.16.x.x then you say that works?
Do you have anything else setup on the switch that is also using the 192.168.x.x range?
10-17-2011 02:33 AM
Here is the 'sh ver':
Copyright (c) 1996-2010 Brocade Communications Systems, Inc.
UNIT 1: compiled on Feb 16 2011 at 05:39:19 labeled as FCXR07202a
(6007397 bytes) from Primary fcxr07202a.bin
SW: Version 07.2.02aT7f3
Boot-Monitor Image size = 369292, Version:07.1.00T7f5 (grz07100)
HW: Stackable FCX624
UNIT 1: SL 1: FCX-24G 24-port Management Module
Serial #: BGF2231F06K
License: FCX_FULL_ROUTER_SOFT_PACKAGE (LID: dihHHIGhFLm)
P-ENGINE 0: type DB10, rev 01
UNIT 1: SL 2: FCX-4XG 4-port 10G Module (4-SFP+)
800 MHz Power PC processor 8544E (version 33/0022) 400 MHz bus
65536 KB flash memory
512 MB DRAM
STACKID 1 system uptime is 144 days 20 hours 6 minutes 25 seconds
The system : started=cold start
We are normally using a public IP space and are distributing them through DHCP. But for some devices there are static entries in the DHCP server for distributing IPs from the private space (We are mixing several subnets in the same VLAN).
On the switch is an IP like 192.168.X.Y/24 configured, but it's not in the same subnet like the private IPs we'd like to distribute over DHCP (e.g. 192.168.a.b/24).
10-17-2011 03:52 AM
With a bit more thought I do not think having a VLAN with multipul ip subnets will work.
IP Helper transforms the DHCP broadcast into a unicast request. Since the unicast address has the router IP address associated with the VE as its source, the DHCP server can take that address and use it to determine the proper scope for the lease but this would work for only one subnet per vlan.
10-18-2011 08:10 AM
I'm pretty shure it should work, because you can add permanent leases to the dhcp server, even if it's on a different subnet.
And we had it working with a freebsd and linux router/dhcrelay. So there must be something on the brocade side which is different than on a linux/freebsd router... It stopped working as soon as we migrated this vlan to the brocade router.