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New Member

WS-C4507R+E chassis with WS-X45-SUP7-E module - DHCP relay problem

Hi experts,

I have this switch and it doesn't relay DHCP packets for certain DHCP clients.

!

interface Vlan853

description VOD_IDF_2A-4A

ip address 172.19.1.6 255.255.255.0

ip helper-address 172.19.255.40

no ip redirects

no ip unreachables

no ip proxy-arp

!

interface Vlan851

description VOD_Servers

ip address 172.19.255.6 255.255.255.0

no ip redirects

no ip unreachables

no ip proxy-arp

!

#ping 172.19.255.40

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 172.19.255.40, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms

A WinXP laptop can get IP fine on VLAN 853 but not a STB. When I do "debug ip dhcp server packets" I see the following errors

Nov 15 12:05:42: DHCPD: option 12 is malformed (option length 0).

Nov 15 12:05:42: DHCPD: invalid DHCP options - unable to parse

(repeated)

The DHCP request packets are discarded by the switch and it is likely because of the above error.

I don't have DHCP snooping turned on. How do I turn off this type of DHCP inspection thing on the switch?

Thanks!

Difan

1 REPLY
New Member

WS-C4507R+E chassis with WS-X45-SUP7-E module - DHCP relay probl

Hi experts,

I just found another post in this forum who had the same problem as mine. He ended up fixing the DHCP client software by stopping sending the option. It won't be easy for me because the STBs are hardcoded firmware and can't do any customized change. Help please!

thanks!

Difan

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