3com 2924-PWR Manual De Usuario

C

HAPTER

 4: M

ANAGING

 D

EVICE

 S

ECURITY

Access Control Lists (ACLs) allow network managers to define 
classification actions and rules for specific ingress ports. A network 
manager can configure an ACL on an ingress port so that packets are 
either admitted or denied entry. The user can also specify that when 
packets are denied entry, the ingress port is also disabled.

For example, an ACL rule is defined stating that port number 20 can 
receive TCP packets, however, if a UDP packet is received, the packet is 
dropped. ACLs are composed of access control entries (ACEs) that are 
made of the filters that determine traffic classifications. 

The following are examples of filters that can be defined as ACEs:

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Source Port IP Address and Wildcard Mask — Filters the packets 
by the source port IP address and wildcard mask.

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Destination Port IP Address and Wildcard Mask — Filters the 
packets by the destination port IP address and wildcard mask.

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ACE Priority — Filters the packets by the ACE priority.

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Protocol — Filters the packets by the IP protocol.

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DSCP — Filters the packets by the DiffServ Code Point (DSCP) value.

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IP Precedence — Filters the packets by the IP Precedence.

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Action — Indicates the action assigned to the packet matching the 
ACL. Packets are forwarded or dropped. In addition, the port can be 
shut down, a trap can be sent to the network administrator, or packet 
is assigned rate limiting restrictions for forwarding. 

This section includes the following topics:

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