Community discussions

MikroTik App
 
sebamikrotik
just joined
Topic Author
Posts: 2
Joined: Tue May 23, 2023 7:38 pm

DHCP option 82 not predictable  [SOLVED]

Tue May 23, 2023 8:11 pm

Hello,

we use RouterOS 7.9 with CRS354-48P-4S+2Q+.

We would like to use DHCP option 82 to allow access via the Circuit-id, now the problem is the Circuit-id is not predictable.

It is the same bridge with DHCP snooping and the Option82 activated, same bridge port configuration etc.. but even if the differ, in my opinion the Circuit-id should be predictable.

In one case it adds 13 in the other case it adds 14.

ether9 + 13 ( in case one ether9 + 13 = 22:10)

DHCP options:
[82] Relay agent information: len = 35
[1] Circuit-id: SWITCH02 eth 0/22:10
[2] Remote-id: ether9

In the other case the Circuit-id is ether43 + 14 = 57)

[82] Relay agent information: len = 36
[1] Circuit-id: SWITCH02 eth 0/57:10
[2] Remote-id: ether43

I've downgrade to 7.7 but all the version show this behavior, I see in wireshark the CRS354 send the "wrong" Circuit-id:.

Any ideas?

Thank you

Seb
 
sebamikrotik
just joined
Topic Author
Posts: 2
Joined: Tue May 23, 2023 7:38 pm

Re: DHCP option 82 not predictable

Wed May 24, 2023 9:04 am

Hello,

I found the problem.

/interface/ethernet/switch/port print show-ids

* NAME SWITCH STORM-RATE
*25 ether24 switch1 100
*26 ether25 switch1 100
*28 ether26 switch1 100
*29 ether27 switch1 100

*27 was missing, this caused the problem with the ports starting from ether26.

Reason was a missing delay in the .rsc file after reset-configuration

ssystem/reset-configuration no-defaults=yes run-after-reset=

After I insert several delays everything works as it should, option 82 is reliably predictable.

Seb

Who is online

Users browsing this forum: Ahrefs [Bot], ItchyAnkle and 82 guests