Unicast DHCPINFORM reply packets swallowed

[jinkama-san]

Hi,

we have a problem here with the DHCP relay feature.

ip helper per-vlan only
ip helper address 10.0.1.1 vlan 100
ip helper forward delay 0
ip helper agent-information policy keep
ip helper dhcp-snooping bypass option-82-check enable
ip helper dhcp-snooping vlan 1
ip helper dhcp-snooping vlan 1 option-82 data-insertion disable
ip helper dhcp-snooping vlan 1 mac-address verification disable
ip helper dhcp-snooping vlan 100
ip helper dhcp-snooping vlan 100 mac-address verification disable
ip helper dhcp-snooping binding enable
ip helper dhcp-snooping option-82 format ascii remote-id vlan interface system-name delimiter "-"
ip helper dhcp-snooping port 1/22 trust

The PC is in VLAN 100, the DHCP server 10.0.1.1 is in VLAN 1 on port 1/22. There is another 6850 involved to the PC, but this one doesn't have any helper or dhcp-snooping configuration.

DHCPDISCOVER, DHCPOFFER, DHCPREQUEST etc all work fine, the PC gets the expected IP.
But when the PC requests additional information with DHCPINFORM, the unicast DHCPACK (RFC2131, 3.4) reply doesn't get forwarded to the PC.
Am I doing something in the configuration? Or is this a bug in 6.4.4.373.R01? The server is ISC DHCP 3.0.7 (SLES10SP4).

Thanks,
Franz

[Paxan76]

try both:
->ip helper standard
->ip helper address 10.0.1.1

[jinkama-san]

Hi,

it turned out to be a real bug in the switch firmware.
It's fixed in at least 6.4.4.530 (tested), possibly already in 6.4.4.508 (untested). The PR is 167584.

Franz.