Thursday 1 September 2011

IOS Access List numbering scheme

The simple CLI parser implemented in early releases of Cisco IOS recognized only numbered access lists. The protocols supported early in the Cisco IOS history were thus using numbered access lists to filter traffic or routing updates.
Most of the access lists were using common address space. Banyan Vines access lists were an exception, they were always configured with the vines access-list configuration command and used their own independent numbering scheme. Rate-limit access-lists (configured with access-list rate-limit number) also use an independent address space.
The first protocol using named access lists was CLNS. Named standard and extended access lists were later added to IP. As numerous IP features still expected an access-list number in the configuration commands even after the named IP access lists were introduced, the address space of the numbered IP access lists was expanded.
The following table documents the IOS access-list numbering conventions:
Start End Description
1 99 IP standard access lists
100 199 IP extended access lists
200 299 Protocol type-code access lists (used in bridging filters)
300 399 DECnet standard access lists
400 499 XNS standard access lists
500 599 XNS extended access lists
600 699 AppleTalk cable range access lists
700 799 MAC address access lists (used in bridging filters)
800 899 Novell IPX standard access lists
900 999 Novell IPX extended access lists
1000 1099 Novell IPX SAP access lists
1100 1199 MAC address access lists (extended range)
1200 1299 Novell IPX NLSP access lists
1300 1999 IP standard access lists (extended range)
2000 2699 IP extended access lists (extended range)
Rate limit access lists configured with the access-list rate-limit global configuration command and used in the rate-limit input|output access-group rate-limit number rate interface configuration command use the following numbers (independent from the access-list numbering scheme):
Start End Description
1 99 Precedence ACL
100 199 MAC address ACL
200 299 MPLS EXP bits ACL
Banyan Vines access lists configured with the vines access-list number global configuration commands used the following numbering scheme:
Start End Description
1 100 Standard ACL
101 200 Extended ACL
201 300 Simple ACL

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