# IPv6 PACL (Port ACL)

**URL:** https://forum.networklessons.com/t/ipv6-pacl-port-acl/3879
**Category:** Lessons Discussion
**Created:** [May 15, 2018, 11:10am UTC](https://forum.networklessons.com/t/ipv6-pacl-port-acl/3879 "2018-05-15T11:10:28Z")
**Posts on this page:** 1
**Showing post:** 2

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### Author: ![davidilles](https://cdn-forum.networklessons.com/user_avatar/forum.networklessons.com/davidilles/32/9686_2.png) [@davidilles](https://forum.networklessons.com/u/davidilles)
#### Post date: [February 11, 2025, 3:16pm UTC](https://forum.networklessons.com/t/ipv6-pacl-port-acl/3879/2 "2025-02-11T15:16:52Z")

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Hello, everyone.

Happy to be the first one to make a post here 😃

I am studying about ACLs for my ENCOR exam and the following piece of information is mentioned in my book:

PACLs have a few restrictions that vary from platform to platform. The following are some  
of the most common restrictions:

> - **PACLs only support filtering incoming traffic on an interface (no outbound filtering support)**
> - **PACLs cannot filter Layer 2 control packets, such as CDP, VTP, DTP, PAgP, UDLD, and**  
> **\> STP.**
> - PACLs are supported only in hardware.
> - **PACLs do not support ACLs to filter IPv6, ARP, or Multiprotocol Label Switching**  
> **(MPLS) traffic**

The highlighted restrictions don’t make much sense to me.

From an architectural perspective, what exactly prevents an ACL that is applied to an L2 interface (so a PACL) from being capable of outbound filtering or filtering IPv6? Sometimes it feels as if these restrictions are made up 😃

Also, why can’t the ACL filter CDP, VTP, etc messages?

//Edit: Rene could filter IPv6 packets inbound here which the following text explains - _PACLs have a few restrictions that **vary from platform to platform** _.

Thank you.

David

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