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Dropping/filtering broadcast packets

Hi, we ran into very strange situation yesterday: clients were unable to get DHCP configuration from DHCP servers.

Wireshark analysis on client machine shows that only "discover" packets are sent (to ff:ff:ff:ff:ff:ff) and clients don't receive "offer" packet from DHCP server. Wireshark analysis on DHCP server shows that "discover" packets are received and "offer" packets are sent back to the client (to ff:ff:ff:ff:ff:ff as expected).

The topology:

- clients are connected to local 3650 access switches (stack)

- catalyst 3650 are connected via port channel to Nexus 9300 (vPC);

- Nexus 9300 (local) are connected to other Nexus 9300 (remote) via vPC (on the remote location)

- Nexus 9300 (remote) are connected to Catalyst 3650 stack switches (remote)

- DHCP server (windows server 2016) is connected to catalyst 3650

 

Next strange issue we observed was clients receive response from DHCP server after approx. 0,5h connected to network.

Successful workaround was disconnecting Nexus switches and connecting Catalyst switches directly via portchannel.

Nexus 9300 is running with latest recommended software: 7.0(3)I5(2).

 

Anyone experienced similar issue?

1 Reply 1

awatson20
Level 4
Level 4
Did you find a solution to this issue? We are experiencing a similar issue with client connecting to a 3650 switch
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