Home > Articles > Cisco Network Technology > General Networking > Cisco IOS IP Accounting Features

Cisco IOS IP Accounting Features

  • Sample Chapter is provided courtesy of Cisco Press.
  • Date: Oct 19, 2007.

Chapter Description

This chapter describes the IP Accounting features in Cisco IOS and enables you to distinguish the different IP Accounting functions and understand SNMP MIB details. This chapter also provides a command-line reference.

IP Accounting Access Control List (ACL)

The IP Accounting ACL identifies IP traffic that fails an IP access control list. This is a relevant security feature, because a sudden increase in traffic being blocked by an ACL can indicate a security attack in the network. Identifying IP source addresses that violate IP access control lists can help track down attackers. Alternatively, this mechanism can be used to identify when an attack is over, because an ACL is usually applied to block the attack. The data might also indicate that you should verify the network element configurations of the IP access control list. It is important to understand that the IP Accounting ACL does not account the amount of traffic that passes an individual ACL; therefore, it cannot be used for ACL optimization. However, the IP Accounting ACL can be used in conjunction with IP Accounting (Layer 3). For example, if ACLs are configured at a router, packets passing all ACLs are accounted by the IP Accounting (Layer 3) feature, and blocked traffic is collected via the IP Accounting ACL.

IP Accounting ACL is supported on ingress and egress traffic. There is no explicit command to recognize if the incoming traffic was blocked (the ip access-group ACL-number IN command, called ACL IN for simplicity) or the outgoing traffic was blocked (the ip access-group ACL-number OUT command, called ACL OUT). Nevertheless, because the blocking access list number is reported by the IP Accounting ACL, the direction can be identified in most cases.

IP Accounting ACL Principles

The principles of IP Accounting ACL can be summarized as follows:

  • It provides information for identifying IP traffic that fails IP ACLs.
  • It supports standard and extended ACLs, but not named ACLS.
  • It supports ACLs applied as both ingress and egress.
  • It has the same database concept as IP Accounting (Layer 3): active and checkpoint databases.
  • If the packet is blocked by an ACL, only the IP Accounting ACL database is updated, not the IP Accounting (Layer 3) database.
  • Collection data is accessible via CLI and SNMP; however, the initial configuration is required via CLI. To retrieve the collection results via SNMP, you need to enable SNMP on the router first. When configuring SNMP, distinguish between read-only access and read-write access. For more details about SNMP configuration, see Chapter 4.
  • The MIB contains only 32-bit SNMP counters.

Supported Devices and IOS Versions

The following list defines the devices and Cisco IOS Software releases that support IP Accounting ACL:

  • IP Accounting ACL was introduced in IOS 10.3.
  • It is supported on all routers, including the RSM and MSFC, except for the Cisco 12000.
  • It is supported on all physical interfaces and logical subinterfaces.
  • It is supported on all switching paths, except for autonomous switching, SSE switching, and dCEF. On the Cisco 7500 router, the IP Accounting ACL causes packets to be switched on the RSP instead of the VIP, which can cause performance degradation.

CLI Operations

Notable commands for configuring, verifying, and troubleshooting IP Accounting ACL are as follows:

  • router(config-if)# ip accounting access-violations

    allows IP Accounting ACL to identify IP traffic that fails IP ACLs.

  • router(config)# ip accounting-threshold count

    sets the maximum number of accounting entries to be created. The accounting threshold defines the maximum number of entries (source and destination address pairs) that are accumulated, with a default of 512 entries.

  • router# show ip accounting [checkpoint] access-violations

    displays the active accounting or checkpoint database for ACL violations.

  • router# clear ip accounting

    copies the content of the active database to the checkpoint database and afterwards clears the active database for both IP Accounting (Layer 3) and IP Accounting ACL.

  • router# clear ip accounting checkpoint

    clears the checkpoint database.

SNMP Operations

IP Accounting ACL uses the same MIB (OLD-CISCO-IP-MIB) as IP Accounting (Layer 3), which was described previously. IP Accounting ACL cannot be configured via SNMP, but a copy function from the active database to the checkpoint database is provided. First, you should copy the active database to the checkpoint database. Afterward, retrieve the data from the checkpoint database if you want to collect consistent accounting data across multiple network elements at the same time. IP Accounting ACL uses the same MIB tables as IP Accounting (Layer 3) but augments the information with the ACL Identifier—the ACL number that was violated by packets from source to destination. The ACL identifier is represented by actViolation in the lipAccountingTable table (the active database) and ckactViolation in the lipCkAccountingTable table (the checkpoint database). actCheckPoint copies the active database into the checkpoint database. For details about the MIB configuration, see the section “SNMP Operations” under “IP Accounting (Layer 3).”

Examples (CLI and SNMP)

The following example for IP Accounting ACL provides CLI and SNMP commands and extends them to display the entries of the IP Accounting (Layer 3) database as well. This helps you understand the close relationship between IP Accounting (Layer 3) and IP Accounting ACL.

Initial Configuration

Initially, the active and checkpoint databases are empty for both IP Accounting (Layer 3) and IP Accounting ACL. An SNMP query to the lipAccountingTable MIB table (active) and to the lipAcCkAccountingTable MIB table (checkpoint) confirms this:

router#show ip accounting output-packets
   Source         Destination          Packets        Bytes
   Accounting data age is 0

router#show ip accounting access-violations
   Source         Destination          Packets        Bytes       ACL
   Accounting data age is 0

router#show ip accounting checkpoint output-packets
   Source         Destination          Packets        Bytes
   Accounting data age is 0

router#show ip accounting checkpoint access-violations
   Source         Destination          Packets        Bytes       ACL
   Accounting data age is 0

For this example, IP Accounting ACL is configured in addition to IP Accounting (Layer 3); however, it can be configured independently of IP Accounting (Layer 3). An access list is inserted, which blocks the traffic coming from the source IP address and going to the destination IP address

router(config)#access-list 107 deny ip host host
router(config)#access-list 107 permit ip any any
router(config)#int serial 0/0
router(config-if)#ip accounting output-packets
router(config-if)#ip accounting access-violations
router(config-if)#ip access-group 107 out

Collection Monitoring

Afterwards, the following results can be retrieved from the router:

router#show ip accounting access-violations
   Source         Destination            Packets         Bytes    ACL                3             300     107
  Accounting data age is 3
router#show ip accounting output-packets
   Source         Destination            Packets         Bytes                5             500
  Accounting data age is 3

Three packets from the traffic (, are blocked by access list 107 and therefore are accounted by the IP Accounting ACL. The traffic (, is accounted by IP Accounting (Layer 3).

For the SNMP example, the router is accessed with SNMP2c, a read community string public, and the net-snmp SNMP utility. The entries from both IP Accounting (Layer 3) and the IP Accounting ACL appear in the same MIB lipAccountingTable table. The only difference is that the entries from the IP Accounting ACL will have a non-null value in the actViolation MIB variable:

SERVER % snmpwalk -c public -v 2c <router> lipAccountingTable
actSrc. = IpAddress:
actSrc. = IpAddress:
actDst. = IpAddress:
actDst. = IpAddress:
actPkts. = INTEGER: 5
actPkts. = INTEGER: 3
actByts. = INTEGER: 500
actByts. = INTEGER: 300
actViolation. = INTEGER: 0
actViolation. = INTEGER: 107

Formatting the result in a different way, the distinction between show ip accounting output-packets and show ip accounting access-violations is clear.

The first entry (show ip accounting output-packets) is

actSrc. = IpAddress:
actDst. = IpAddress:
actPkts. = INTEGER: 5
actByts. = INTEGER: 500
actViolation. = INTEGER: 0

The second entry (show ip accounting access-violations) is

actSrc. = IpAddress:
actDst. = IpAddress:
actPkts. = INTEGER: 3
actByts. = INTEGER: 300
actViolation. = INTEGER: 107

At this point, the checkpoint database is still empty. The clear ip accounting CLI command or the actCheckPoint MIB variable procedure copies the active database content to the checkpoint database. The two entries just discussed are now in the checkpoint database, and the active database is empty.

router#show ip accounting checkpoint access-violations
   Source         Destination              Packets             Bytes    ACL                  3                 300     107
  Accounting data age is 10

router#show ip accounting checkpoint output-packets
   Source         Destination              Packets             Bytes                  5                 500
  Accounting data age is 10

router#show ip accounting access-violations
   Source         Destination              Packets             Bytes    ACL
  Accounting data age is 11

router#show ip accounting output-packets
   Source         Destination              Packets             Bytes
  Accounting data age is 11

SERVER % snmpwalk -c public -v 2c <router> lipcKAccountingTable
ckactSrc. = IpAddress:
ckactSrc. = IpAddress:
ckactDst. = IpAddress:
ckactDst. = IpAddress:
ckactPkts. = INTEGER: 5
ckactPkts. = INTEGER: 3
ckactByts. = INTEGER: 500
ckactByts. = INTEGER: 300
ckactViolation. = INTEGER: 0
ckactViolation. = INTEGER: 107
3. IP Accounting MAC Address | Next Section Previous Section

Cisco Press Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from Cisco Press and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about Cisco Press products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites; develop new products and services; conduct educational research; and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@ciscopress.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by Cisco Press. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.ciscopress.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020