xStack DES-3800 Series Layer 3 Stackable Fast Ethernet Managed Switch CLI Manual
162
this case, when a logical AND operation between an IP address specified in the next step and the
ip_source_mask
match.
The default for an access profile on the Switch is to
permit
traffic flow. If you want to restrict traffic, you
must use the
deny
parameter.
Now that an access profile has been created, you must add the criteria the Switch will use to decide if a
given frame should be forwarded or filtered. Here, we want to filter any packets that have an IP source
address between 10.42.73.0 and 10.42.73.255:
config access_profile profile_id 1 add access_id 1 ip source_ip 10.42.73.1 port 1:1 deny
Here we use the
profile_id 1
which was specified when the access profile was created. The
add
parameter instructs the Switch to add the criteria that follows to the list of rules that are associated with
access profile 1. For each rule entered into the access profile, you can assign an
access_id
that both
identifies the rule and establishes a priority within the list of rules. A lower
access_id
gives the rule a
higher priority. In case of a conflict in the rules entered for an access profile, the rule with the highest
priority (lowest
access_id
) will take precedence.
The
ip
parameter instructs the Switch that this new rule will be applied to the IP addresses contained
within each frame’s header.
source_ip
tells the Switch that this rule will apply to the source IP addresses
in each frame’s header. Finally, the IP address
10.42.73.1
will be combined with the
source_ip_mask
255.255.255.0
to give the IP address 10.42.73.0 for any source IP address between 10.42.73.0 to
10.42.73.255.
Due to a chipset limitation, the Switch supports a maximum of 9 access profiles. The rules used to define
the access profiles are limited to a total of 800 rules for the Switch.
There is an additional limitation on how the rules are distributed among the Fast Ethernet and Gigabit
Ethernet ports. This limitation is described as follows: Fast Ethernet ports are limited to 200 rules for each
of the three sequential groups of eight ports. That is, 200 ACL profile rules may be configured for ports 1
to 8. Likewise, 200 rules may be configured for ports 9 to 16, and another 200 rules for ports 17 to 24. Up
to 100 rules may be configured for each Gigabit Ethernet port. The table below provides a summary of
the maximum ACL profile rule limits.
Port Numbers
Maximum ACL Profile Rules per Port Group
1 - 8
200
9 – 16
200
17 - 24
200
25 (Gigabit)
100
26 (Gigabit)
100
27 (Gigabit)
100
28 (Gigabit)
100
Total ACL Rules
800
It is important to keep this in mind when setting up VLANs as well. Access rules applied to a VLAN
require that a rule be created for each port in the VLAN. For example, let’s say VLAN10 contains ports 2,
11 and 12. If you create an access profile specifically for VLAN10, you must create a separate rule for
each port. Now take into account the rule limit. The rule limit applies to both port groups 1-8 and 9-16
since VLAN10 spans these groups. One less rule is available for port group 1-8. Two less rules are
available for port group 9-16. In addition, a total of three rules apply to the 800 rule Switch limit.
In the example used above - config access_profile profile_id 1 add access_id 1 ip source_ip 10.42.73.1
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