Beware off using ACL filtering on 6500s with many vlans (100+) and long acls (hundred+ lines)... You'll soon find out more than you ever wanted to know about TCAM, different TCAM types used in various sup's and what the limitations imposed by TCAM on processing ACLs in hardware... Sam Crooks -----Original Message----- From: Michael Helmeste [mailto:mhelmest@uvic.ca] Sent: Tuesday, April 07, 2009 3:06 PM To: nanog@nanog.org Subject: ACLs vs. full firewalls Hi all, One of the duties of my current place of employ is reorganizing the network. We have a few Catalyst 6500 series L3 switches, but currently do all packet filtering (and some routing) using a software based firewall. Don't ask me, I didn't design it :) Current security requirements are only based on TCP and non-stateful UDP src/dst net/port filtering, and so my suggestion was to use ACLs applied on the routed interface of each VLAN. There was some talk of using another software based firewall or a Cisco FWSM card to filter traffic at the border, mostly for management concerns. We expect full 1 gig traffic levels today, and 10 gig traffic levels in the future. I view ACLs as being a cheap, easy to administrate solution that scales with upgrades to new interface line speeds, where a full stateful firewall isn't necessary. However, I wanted to get other opinions of what packet filtering solutions people use in the border and in the core, and why. What's out there, and why do you guys use it? How do you feel about the scalability, performance, security, and manageability of your solution? What kind of traffic levels do you put through it?