OS6200 DHCP snooping don't working good

[nikolami]

Hello,

I tested DHCP snooping option on OS6200 and OS6600 (separately). On one switch, in the same VLAN 40, are connected DHCP server and client (PC).


On OS6200 switch snooping working partially - PC client is not able to get IP address. But when port on which DHCP server is connected is configured as trust the situation remains the same.
Software version is the newest one (1.7.1.7).

Configuration for DHCP clients:
OS6248P_->(config)# ip dhcp snooping
OS6248P_->(config)# ip dhcp snooping vlan 40
OS6248P_->(config)# ip dhcp snooping information option allowed-untrusted

Port for DHCP server:
OS6248P_->(config)# interface ethernet e13
OS6248P_->(config-if)# ip dhcp snooping trust

On OS6600 DHCP snooping don't preventing DHCP server at all. In every situation DHCP client gets IP address from server.
Release 5.4.1.R01 is mandatory for DHCP Snooping since 5.1.6 don't support this feature.

per switch:
OS6600P24_-> ip helper dhcp-snooping enable
OS6600P24_-> ip helper dhcp-snooping option-82 data-insertion enable

or per VLAN:
OS6600P24_-> ip helper dhcp-snooping option-82 data-insertion enable
OS6600P24_-> ip helper dhcp-snooping vlan 40

On OS6600 DHCP snooping per switch and per VLAN are mutually exclusive, but on OS6200 must be configured both?!

OS6600P24_-> ip helper dhcp-snooping vlan 40
ERROR: Switch and VLAN based DHCP Snooping are mutually exclusive


Does anyone have experience with DHCP snooping on Alcatel OmniSwitches?
What is the situation on newer AOS switches (OS6850, OS6250)?


Regards,
Nikolami

[benny]

Hi Nikolami,

I don't have experience with "dhcp snooping" on OS6200 but wanted to let you know that AOS 6.4.4.R01 will contain new options for dhcp snooping (IP SRC filter options etc). I'll look into that and maybe write an article on that once I have time.

-benny

[nikolami]

Thank you Benny for info.

I hope that someone has experience with configuring DHCP snooping on AOS switch (OS6600, OS6850 or OS6250) and on OS6200. Because I faced with problems on both Alcatel's platforms with "DHCP Snooping" functionality.

Regards,

nikolami

[Bunleang Meng]

I have problem with DHCP snooping also
when i do

ip helper dhcp-snooping enable
ip helper dhcp-snooping binding enable
ip helper dhcp-snooping ip-source-filter port 1/1-48 enable (Connect to end device)
ip helper dhcp-snooping port 1/50 trust (uplink)

all pc client not receive dhcp form dhcp server ?

[silvio]

Your AOS-commands are in the total wrong Board.... Please post it again with your correct switch.
Than change you second line to "ip helper dhcp-snooping binding persistency enable" and post the output of:

Code: Select all

> show ip helper dhcp-snooping binding
> show ip helper dhcp-snooping port
> show configuration snapshop ip-helper

regards
Silvio

[Barrykeery]

Are you saying that my other 4 scopes need teh option 43 and NOT the VIOIP VLAN?? Do i need to add 125 and 128 as well? If so they have never been there.