Users Guide

interval of 5 minutes is used. Similarly, if you do not specify the threshold for ACL logs, a default threshold of 10 is used, where this value
refers to the number of packets that are matched against an ACL .
A Layer 2 or Layer 3 ACL contains a set of defined rules that are saved as flow processor (FP) entries. When you enable ACL logging for a
particular ACL rule, a set of specific ACL rules translate to a set of FP entries. You can enable logging separately for each of these FP
entries, which relate to each of the ACL entries configured in an ACL. Dell Networking OS saves a table that maps each ACL entry that
matches the ACL name on the received packet, sequence number of the rule, and the interface index in the database. When the
configured maximum threshold has exceeded, log generation stops. When the interval at which ACL logs are configured to be recorded
expires, a fresh interval timer starts and the packet count for that new interval commences from zero. If ACL logging was stopped
previously because the configured threshold has exceeded, it is reenabled for this new interval.
The ACL application sends the ACL logging configuration information and other details, such as the action, sequence number, and the ACL
parameters that pertain to that ACL entry. The ACL service collects the ACL log and records the following attributes per log message.
• For non-IP packets, the ACL name, sequence number, ACL action (permit or deny), source and destination MAC addresses,
EtherType, and ingress interface are the logged attributes.
• For IP Packets, the ACL name, sequence number, ACL action (permit or deny), source and destination MAC addresses, source and
destination IP addresses, and the transport layer protocol used are the logged attributes.
• For IP packets that contain the transport layer protocol as Transmission Control Protocol (TCP) or User Datagram Protocol (UDP),
the ACL name, sequence number, ACL action (permit or deny), source and destination MAC addresses, source and destination IP
addresses, and the source and destination ports (Layer 4 parameters) are also recorded.
If the packet contains an unidentified EtherType or transport layer protocol, the values for these parameters are saved as Unknown in the
log message. If you also enable the logging of the count of packets in the ACL entry, and if the logging is deactivated in a specific interval
because the threshold has exceeded, the count of packets that exceeded the logging threshold value during that interval is recorded
when the subsequent log record (in the next interval) is generated for that ACL entry.
Guidelines for Configuring ACL Logging
This functionality is supported on the platform.
Keep the following points in mind when you configure logging of ACL activities:
• During initialization, the ACL logging application tags the ACL rule indices for which a match condition exists as being in-use, which
ensures that the same rule indices are not reused by ACL logging again.
• The ACL configuration information that the ACL logging application receives from the ACL manager causes the allocation and
clearance of the match rule number. A unique match rule number is created for the combination of each ACL entry, sequence number,
and interface parameters.
• A separate set of match indices is preserved by the ACL logging application for the permit and deny actions. Depending on the action
of an ACL entry, the corresponding match index is allocated from the particular set that is maintained for permit and deny actions.
• A maximum of 125 ACL entries with permit action can be logged. A maximum of 126 ACL entries with deny action can be logged.
• For virtual ACL entries, the same match rule number is reused. Similarly, when an ACL entry is deleted that was previously enabled for
ACL logging, the match rule number used by it is released back to the pool or available set of match indices so that it can be reused for
subsequent allocations.
• If you enabled the count of packets for the ACL entry for which you configured logging, and if the logging is deactivated in a specific
interval owing to the threshold having exceeded, the count of packets that exceeded the logging threshold value during that interval is
logged when the subsequent log record (in the next interval) is generated for that ACL entry.
• When you delete an ACL entry, the logging settings associated with it are also removed.
• ACL logging is supported for standard and extended IPv4 ACLs, IPv6 ACLs, and standard and extended MAC ACLs.
• For ACL entries applied on port-channel interfaces, one match index for every member interface of the port-channel interface is
assigned. Therefore, the total available match indices of 251 are split (125 match indices for permit action and 126 match indices for
the deny action).
• You can configure ACL logging only on ACLs that are applied to ingress interfaces; you cannot enable logging for ACLs on egress
interfaces.
• The total available match rule indices is 255 with four match indices used by other modules, leaving 251 indices available for ACL
logging.
Configuring ACL Logging
This functionality is supported on the platform.
To configure the maximum number of ACL log messages to be generated and the frequency at which these messages must be generated,
perform the following steps:
Access Control Lists (ACLs)
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