IP Addresses and Services Configuration Guide for Cisco 8000 Series Routers, IOS XR Releases

PDF

IP Addresses and Services Configuration Guide for Cisco 8000 Series Routers, IOS XR Releases

IP access list entry sequence numbering

Updated: August 12, 2026

Want to summarize with AI?

Log in

This topic describes the IP access list entry sequence numbering feature on the Cisco 8000 Series Router, which allows you to add sequence numbers to access-list entries and resequence them.

The IP Access List Entry Sequence Number is an ACL configuration feature that

  • simplifies access list modifications

  • enables precise positioning of entries within a list, and

  • eliminates the need to remove and re-enter existing entries during updates.

The IP access list entry sequence numbering feature allows users to add sequence numbers to access-list entries and resequence them. When you add a new entry, you choose the sequence number so that it is in a desired position in the access list. If necessary, entries currently in the access list can be resequenced to create room to insert the new entry.

Table 1. Feature History Table

Feature Name

Release Information

Feature Description

IP Access List Entry Sequence Numbering

Release 26.2.1

Introduced in this release on: Modular Systems (8800 [LC ASIC: P100]):*

*This feature is supported on:

  • 88-LC1-48Y8H-EM

IP Access List Entry Sequence Numbering

Release 25.4.1

Introduced in this release on: Fixed Systems (8010 [ASIC: A100])(select variants only*)

The IP Access List Entry Sequence Numbering feature makes managing access lists easier and less error-prone by allowing you to assign sequence numbers to each entry. You can insert, reorder, or resequence entries without removing and re-entering the entire list. By specifying a sequence number, new entries are placed exactly where needed, and the system automatically numbers entries when not specified. Sequence numbers are synchronized across the route processor and line cards, and this feature works with both standard and extended named IP access lists.

*This feature is supported on:

  • 8011-32Y8L2H2FH

  • 8011-12G12X4Y-A/D

  • 8011-4G24Y4H-I

Sequence numbering behavior

These are the details of the sequence numbering behavior:

  • If entries with no sequence numbers are applied, the first entry is assigned a sequence number of 10, and successive entries are incremented by 10. The maximum configurable sequence number is 2147483643 for IPv4 and IPv6 entries. For other entries, the maximum configurable sequence number is 2147483646. If the generated sequence number exceeds this maximum number, the following message displays:

    Exceeded maximum sequence number.

  • If you provide an entry without a sequence number, it is assigned a sequence number that is 10 greater than the last sequence number in that access list and is placed at the end of the list.

  • ACL entries can be added without affecting traffic flow and hardware performance.

  • If a new access list is entered from global configuration mode, then sequence numbers for that access list are generated automatically.

  • Distributed support is provided so that the sequence numbers of entries in the route processor (RP) and line card (LC) are synchronized at all times.

  • This feature works with named standard and extended IP access lists. Because the name of an access list can be designated as a number, numbers are acceptable.

Example: Add entries with sequence numbers

In the following example, a new entry is added to IPv4 access list acl_5.

ipv4 access-list acl_5
 2 permit ipv4 host 192.0.2.1 any
 5 permit ipv4 host 198.51.100.44 any
 10 permit ipv4 host 198.51.100.1 any
 20 permit ipv4 host 198.51.100.2 any
configure
ipv4 access-list acl_5
 15 permit 203.0.113.1 255.255.255.0
end
ipv4 access-list acl_5
 2 permit ipv4 host 192.0.2.1 any
 5 permit ipv4 host 198.51.100.44 any
 10 permit ipv4 host 198.51.100.1 any
 15 permit ipv4 203.0.113.1 255.255.255.0 any
 20 permit ipv4 host 198.51.100.2 any

Example: Add entries without sequence numbers

The following example shows how an entry with no specified sequence number is added to the end of an access list. When an entry is added without a sequence number, it is automatically given a sequence number that puts it at the end of the access list. Because the default increment is 10, the entry will have a sequence number 10 higher than the last entry in the existing access list.

configure
ipv4 access-list acl_10
permit 192.0.2.1 255.255.255.0
permit 198.51.100.1 255.255.255.0
permit 203.0.113.1 255.255.255.0
end

ipv4 access-list acl_10
 10 permit ip  192.0.2.1 255.255.255.0 any
 20 permit ip  198.51.100.1 255.255.255.0 any
 30 permit ip  203.0.113.1 255.255.255.0 any

configure
ipv4 access-list acl_10
permit  203.0.113.5 255.255.255.0
end

ipv4 access-list acl_10
 10 permit ip  192.0.2.1 255.255.255.0 any
 20 permit ip  198.51.100.1 255.255.255.0 any
 30 permit ip  203.0.113.1 255.255.255.0 any
 40 permit ip  203.0.113.5 255.255.255.0 any