Content

| 6.1 |  | Characteristics of Transport Layer Technologies |
| 6.1.4 |  | Standard access control lists |

Recall that access control lists (ACLs) can be implemented on routers to permit and deny traffic that matches predefined profiles. Traffic profiles can be configured to match individual hosts, parts of networks, or entire ranges of networks, and can apply to all IP traffic, or traffic using a specific source or destination port. Access lists can also be used to filter traffic for other operations on the network equipment, particularly network management traffic destined to a network switch or router.

Standard access lists examine only the source address of packets. This means they must be implemented at each ingress point for a protected destination. Implementing the standard access list as close to the protected destination as possible reduces the total number of access lists required.

Numbered standard access lists can be used for filtering traffic being forwarded or received by a router or switch. Numbered standard access lists use the number ranges 1-99 and 1300-1999.

Named standard ACLs have the same capabilities and limitations as numbered standard ACLs. The main advantage of a named ACL is better documentation, as the ACL can be named according to its purpose. One significant disadvantage is that other processes, such as SNMP security, cannot reference named standard ACLs.

Figure shows the command syntax for creating numbered standard access lists.

Figure shows the command syntax for creating named standard access lists.