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This is official, we have almost reached the capacity of our public IP addresses (20,000 just on Wireless) We love IPv6, but for the moment it's not going to solve our issue! So, NAT it is, and we have zero experience besides our visitor network that handles 1000+ users. Our plan is to terminate NAT on our Fortinet firewalls, and assign 32 VLANs (in our Aruba VLAN pools) with a private /21 in each subnet. So ~64,000 IP addresses. We block mDNS etc... no worries there. We can now move away from the 30 minutes lease time and go to... I was thinking 12 or 14 hours. We plan to do NAT-PAT 1 public to 8 private IP ratio or 1 to 16. People with similar size networks: Anything to worry about? DHCP capacity, NAT capacity, Logs, ... Thank you in advance for your input, Philippe Hanset Univ. of TN, Knoxville ********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at


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We have been running PAT (NAT) for over 5 years now on our wireless network. This year we have over 10k concurrent users on wireless. Meru provides the majority of our wireless network gear. We have 3 SSIDs (captive portal, 802.1x, and guest). Each of these 3 SSID's is assigned a single /19 of 172.18. space (Meru suppresses broadcast at the AP). We use Cisco ASA 5580's as the devices managing the PAT translations and L3 interfaces. We assign 1 overload address per 256 addresses. Our DHCP timeout is set to 2 hours. From a network perspective this has been working just fine. If you want any other details let me know. -- Jason E. Murray Sr. Systems Engineer Washington University in St. Louis Phone: 314-935-4865 Email: Web:

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