CWA on ISE and switches

Question

I was able to configure the CWA on the switch and Cisco ISE. It is working as expected. I followed the guide on the link bellow.
http://www.cisco.com/en/US/products/ps11640/products_configuration_example09186a0080ba6514.shtml
I only have one question. I try to understand why ACL must be configured on the port on the switch. Guide uses ACL with name webauth which permit all traffic. If port is authorized it receives dACL from ISE, otherwise port is in unauthorize state and denies all traffic.
interface GigabitEthernet1/0/12
description ISE1 - dot1x clients - UCS Eth0
switchport access vlan 100
switchport mode access
ip access-group webauth in
authentication order mab
authentication priority mab
authentication port-control auto
mab
spanning-tree portfast
end
ip access-list extended webauth
permit ip any any

Answer 1

Why ACL must be configured on the port on the switch
Question:
I only have one question. I try to understand why ACL must be configured on the port on the switch. Guide uses ACL with name webauth which permit all traffic. If port is authorized it receives dACL from ISE, otherwise port is in unauthorize state and denies all traffic.
What is Web Authentication?
Web authentication is opposed to local web authentication, which is the usual web authentication on the switch itself. In that system, upon dot1x/mab failure, the switch wills failover to the webauth profile and will redirect client traffic to a web page on the switch.
Role of ACL:
The redirectACL sent back with the central webauth profile determines which traffic (HTT or HTTPS) is redirected to the ISE. The downloadable ACL allows you to define what traffic is allowed. You should typically allow for DNS, HTTP(S), and 8443 and deny the rest. Otherwise, the switch redirects HTTP traffic but allows other protocols.
Port ACLs
Port ACLs are ACLs that are applied to Layer 2 interfaces on a switch. Port ACLs are supported only on physical interfaces and not on EtherChannel interfaces and can be applied only on interfaces in the inbound direction. These access lists are supported:
•Standard IP access lists using source addresses
•Extended IP access lists using source and destination addresses and optional protocol type information
•MAC extended access lists using source and destination MAC addresses and optional protocol type information
The switch examines ACLs associated with all inbound features configured on a given interface and permits or denies packet forwarding based on how the packet matches the entries in the ACL. In this way, ACLs control access to a network or to part of a network.  Figure is an example of using port ACLs to control access to a network when all workstations are in the same VLAN. ACLs applied at the Layer 2 input would allow Host A to access the Human Resources network, but prevent Host B from accessing the same network. Port ACLs can only be applied to Layer 2 interfaces in the inbound direction.
Figure 31-1 Using ACLs to Control Traffic to a Network
When you apply a port ACL to a trunk port, the ACL filters traffic on all VLANs present on the trunk port. When you apply a port ACL to a port with voice VLAN, the ACL filters traffic on both data and voice VLANs.
With port ACLs, you can filter IP traffic by using IP access lists and non-IP traffic by using MAC addresses. You can filter both IP and non-IP traffic on the same Layer 2 interface by applying both an IP access list and a MAC access list to the interface.
For More information, please check
http://www.cisco.com/en/US/docs/switches/lan/catalyst2960/software/release/12.2_55_se/configuration/guide/swacl.html#wp1715468