Cisco 6500 - Catalyst Series 10 Gigabit EN Interface Module Expansion, Configuration Manual, Page: 238 / 742

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Catalyst 6500 Series Switch and Cisco 7600 Series Router Firewall Services Module Configuration Guide using ASDM
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Chapter 13 Identifying Traffic with Access Lists
Simplifying Access Lists with Object Grouping
•
TrustedHosts—Includes the host and network addresses allowed access to the greatest range of
services and servers
• PublicServers—Includes the host addresses of servers to which the greatest access is provided
After creating these groups, you could use a single ACE to allow trusted hosts to make specific service
requests to a group of public servers.
You can also nest object groups in other object groups.
Note
The ACE system limit applies to expanded access lists. If you use object groups in ACEs, the number of
actual ACEs that you enter is fewer, but the number of expanded ACEs is the same as without object
groups. In many cases, object groups create more ACEs than if you added them manually, because
creating ACEs manually leads you to summarize addresses more than an object group does. To view the
number of expanded ACEs in an access list, enter the
show access-list command.
For example, consider a network object group with 100 sources, a network object group with 100
destinations, and a port object group with 5 ports. Permitting the ports from sources to destinations could
result in 50,000 ACEs (5 x 100 x 100) in the expanded access list.
Adding Object Groups
This section describes how to add object groups, and includes the following topics:
•
Adding a Protocol Object Group, page 13-12
•
Adding a Network Object Group, page 13-13
• Adding a Service Object Group, page 13-14
•
Adding an ICMP Type Object Group, page 13-14
Adding a Protocol Object Group
To add or change a protocol object group, perform the following steps. After you add the group, you can
add more objects as required by following this procedure again for the same group name and specifying
additional objects. You do not need to reenter existing objects; the commands you already set remain in
place unless you remove them with the
no form of the command.
To add a protocol group, perform the following steps:
Step 1
To add a protocol group, enter the following command:
hostname(config)# object-group protocol grp_id
The grp_id is a text string up to 64 characters in length.
The prompt changes to protocol configuration mode.
Step 2
(Optional) To add a description, enter the following command:
hostname(config-protocol)# description text
The description can be up to 200 characters.
Step 3
To define the protocols in the group, enter the following command for each protocol:
hostname(config-protocol)# protocol-object protocol