Option 82 problem

Bob Harold rharolde at umich.edu
Fri Apr 17 16:26:37 UTC 2020


On Fri, Apr 17, 2020 at 10:18 AM Александр Сандецкий <
alexander.sandetsky at gmail.com> wrote:

> Hi!
>
> I have a problem with option 82 configuration.
>
> I have managed switch with IP 10.10.0.38 (managed VLAN 100). There is
> additional VLANs configured for clients: VLAN 3000 and 3010. There is
> option 82 and DHCP relay configured on the switch.
>
> I have DHCP server placed in VLAN 3000 with IP 172.18.0.101
>
> I want to DHCP server serves the VLAN 3010 (and other) on per-VLAN basis.
>
> The part of dhcpd.conf
>
> class "VLAN3010" {
>         match if binary-to-ascii(10, 8, "", substring(option
> agent.circuit-id, 2, 2)) = "3010"
>     }
>
>
> subnet 172.18.10.0 netmask 255.255.255.0 {
>     option routers  172.18.0.1;
>
>     pool {
>             range 172.18.10.51 172.18.10.250;
>             allow members of "VLAN3010";
>     }
> }
>
>
> The server receives request as
> DHCPDISCOVER from 2c:27:d7:b1:a2:85 via 10.10.0.38: network 10.10.0.0/24:
> no free leases
>
>
The packet came from 10.10.0.38, which is not in the subnet, so even if the
class matched, it would not get an IP from that subnet.
As it says, network 10.10.0.0/24 has no free leases

-- 
Bob Harold


>
>
> I have checked with Wireshark
>
>    Option: (82) Agent Information Option
>         Length: 18
>         Option 82 Suboption: (1) Agent Circuit ID
>             Length: 6
>             Agent Circuit ID: 00040bc20003
>         Option 82 Suboption: (2) Agent Remote ID
>             Length: 8
>             Agent Remote ID: 00068026897b2b40
>
> There is binary encoded agent circuit id that contains "0bc2" bytes that
> equal to "3010" in decimal.
>
> Why my class definition does not accept this request? What is wrong?
>
>
>
> --
>
> Regards,
> Alexander
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>
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