Users Guide

NOTE: When assigning sequence numbers to filters, you may have to insert a new filter. To prevent reconfiguring multiple
filters, assign sequence numbers in multiples of five or another number.
The example below shows how the seq command orders the filters according to the sequence number assigned. In the example, filter 15
was configured before filter 5, but the show config command displays the filters in the correct order.
Dell(config-ext-nacl)#seq 15 deny ip host 112.45.0.0 any log
Dell(config-ext-nacl)#seq 5 permit tcp 12.1.3.45 0.0.255.255 any
Dell(config-ext-nacl)#show confi
!
ip access-list extended dilling
seq 5 permit tcp 12.1.0.0 0.0.255.255 any
seq 15 deny ip host 112.45.0.0 any log
Dell(config-ext-nacl)#
Configuring Filters Without a Sequence Number
If you are creating an extended ACL with only one or two filters, you can let the system assign a sequence number based on the order in
which the filters are configured. Filters are assigned in multiples of five.
To configure a filter for an extended IP ACL without a specified sequence number, use any or all of the following commands:
• Configure a deny or permit filter to examine IP packets.
CONFIG-EXT-NACL mode
{deny | permit} {source mask | any | host ip-address} [count [byte]] [order] [fragments]
• Configure a deny or permit filter to examine TCP packets.
CONFIG-EXT-NACL mode
{deny | permit} tcp {source mask] | any | host ip-address}} [count [byte]] [order] [fragments]
• Configure a deny or permit filter to examine UDP packets.
CONFIG-EXT-NACL mode
{deny | permit} udp {source mask | any | host ip-address}} [count [byte]] [order] [fragments]
When you use the log keyword, the CP logs details about the packets that match. Depending on how many packets match the log entry
and at what rate, the CP may become busy as it has to log these packets’ details.
The following example shows an extended IP ACL in which the sequence numbers were assigned by the software. The filters were
assigned sequence numbers based on the order in which they were configured (for example, the first filter was given the lowest sequence
number). The show config command in IP ACCESS LIST mode displays the two filters with the sequence numbers 5 and 10.
Example of Viewing Filter Sequence for a Specified Extended ACL
Dell(config-ext-nacl)#deny tcp host 123.55.34.0 any
Dell(config-ext-nacl)#permit udp 154.44.123.34 0.0.255.255 host 34.6.0.0
Dell(config-ext-nacl)#show config
!
ip access-list extended nimule
seq 5 deny tcp host 123.55.34.0 any
seq 10 permit udp 154.44.0.0 0.0.255.255 host 34.6.0.0
Dell(config-ext-nacl)#
To view all configured IP ACLs and the number of packets processed through the ACL, use the show ip accounting access-list
command in EXEC Privilege mode, as shown in the first example in Configure a Standard IP ACL Filter.
Configure Layer 2 and Layer 3 ACLs
Both Layer 2 and Layer 3 ACLs may be configured on an interface in Layer 2 mode.
If both L2 and L3 ACLs are applied to an interface, the following rules apply:
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Access Control Lists (ACLs)