problem with DHCP Relay

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damjan123
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problem with DHCP Relay

Post by damjan123 » 08 Apr 2015 05:06

Dear All,

I have a problem with DHCP Relay on Alcatel OmniSwitch 6860. The problem that occur is only when the Alcatel Switch is configured with ip static routes and vlan interfaces. The DHCP server is on Linux Virtual Machine. The main problem is that users don't take IP address from the desired VLAN. e.g if that port is in VLAN 2, the user take IP from vlan 1, because on the dhcp server that MAC address in the past 2 hours was with ip from vlan 1. The client have one DHCP server for 60 vlans with one IP. All Ip helpers are per vlan with that specific vlan, ip helper forward delay is 0 and option 82 is disabled.
When the Vlan IP interfaces and routes are on CISCO switch everything is working, user from vlan 2 will have ip from scope of VLAN 2(the cisco switch have only one up link from the Alcatel switch), the cisco is configured also with ip helper per vlan.

What should be the problem, the conf on the alcatel is same as on the cisco.

devnull
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Re: problem with DHCP Relay

Post by devnull » 08 Apr 2015 06:00

Afaik there was a known bug with dhcp relay on 6900 so it may be present in 6860 as well.
It should work, but i have not tested it with 6860.

update to latetest build, grab a wireshark trace of a request where Alcatel is relay and one where cisco does the job. open a SR.

On 6900 it is:
ip helper per-vlan-only
ip helper vlan 1 address 10.0.0.3
ip helper vlan 300 address 10.22.20.190
ip helper vlan 410 address 10.0.0.3
ip helper vlan 420 address 10.0.0.3

If you have only one server you do not need per-vlan just set a "global" dhcp-server to relay to.

damjan123
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Posts: 8
Joined: 18 Apr 2013 18:38

Re: problem with DHCP Relay

Post by damjan123 » 08 Apr 2015 07:23

i've tried that also, the same thing happens. today i will take trace from cisco and alcatel. i will try with 6850 also, just to see this problem will occur again

damjan123
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Posts: 8
Joined: 18 Apr 2013 18:38

Re: problem with DHCP Relay

Post by damjan123 » 08 Apr 2015 10:18

With Alcatel Switch 6850 DHCP is working. I will see the traces but probably the problem is with the Firmware of the 6860.

devnull
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Re: problem with DHCP Relay

Post by devnull » 08 Apr 2015 10:33

Which Firmware do you use= 8.1.1.585 or the GA?

damjan123
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Posts: 8
Joined: 18 Apr 2013 18:38

Re: problem with DHCP Relay

Post by damjan123 » 09 Apr 2015 02:44

8.1.1.585.R01. Is there any newer?

devnull
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Re: problem with DHCP Relay

Post by devnull » 09 Apr 2015 03:51

This is the last available. Open a SR, there have been a couple of DHCP relay fixes in 7.3.3 maybe they need to be incorperated in 6860/8.1.1 as well.
Please update here if you got a reply from TAC

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