We run an all cisco network wth a 6500 core switch and 3500 access layer switches.
In one instance a customer had a VOIP gateway device plugged in improperly and as a result all clients on that specific VLAN looses their regularly assigned IP address and picks up on from the VOIP Gateway which is setup to be a DHCP server.
Is there anything that can be doneto prevent unauthorized DHCP servers from causing outages such as these?
The newer switches have a feature called dhcp snooping which prevents unauthorised DHCP servers taking out your network. Unfortunately I don't believe that your legacy 3500 switches will have support for this feature.
TBH I don't think there is much you can do from where you are. As mentioned, DHCP snooping may help, but another aspect to consider - How big are your subnets? Smaller subnets would mean fewer users would be affected by an incident like this.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.