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L3 HP switch not preventing DHCP flooding

 
lucaprete
Occasional Visitor

L3 HP switch not preventing DHCP flooding

Hello everyone,

 

I've an HP switch (HP 5400zl E5406 ZL - J8697A v2 with firmware K.15.17.0007) that I use as L3 switch to do inter-vlan routing for my LAN network.

Since it's supported, I also configured a DHCP server on it.

 

For some other firmware errors, I discovered I've two hosts on the network that keep asking new IP addresses to the DHCP server (every 5 seconds). I don't know why, the DHCP start to associate different IPs (at the same time!!) to the same MAC address, without never releasing (before the lease time expires) the addresses.

I've a lease time configured, so I really don't understand why this happens..

 

My config is the following:

dhcp-server pool "10"
   authoritative
   default-router "10.1.8.1"
   dns-server "192.168.1.1,8.8.8.8"
   lease 00:18:00
   network 10.1.8.0 255.255.252.0
   range 10.1.8.10 10.1.9.255
   exit

 

This is bad, since as soon as I turn on those devices the addresses in the DHCP pool finish in a second.

 

Count on your help!

 

Thanks,

 

Luca