- Cisco BGP Overview
- Configuring a Basic BGP Network
- Connecting to a Service Provider Using External BGP
- Configuring BGP Neighbor Session Options
- Configuring Internal BGP Features
- Configuring Advanced BGP Features
- BGP Link Bandwidth
- iBGP Multipath Load Sharing
- BGP Multipath Load Sharing for Both eBGP and iBGP in an MPLS-VPN
- Loadsharing IP Packets Over More Than Six Parallel Paths
- BGP Policy Accounting
- BGP Policy Accounting Output Interface Accounting
- BGP Cost Community
- BGP Support for IP Prefix Import from Global Table into a VRF Table
- Per-VRF Assignment of BGP Router ID
- BGP Next Hop Unchanged
IP Routing: BGP Configuration Guide, Cisco IOS Release 12.2SY
- Updated:
- July 11, 2017
Chapter: BGP Policy Accounting Output Interface Accounting
- Finding Feature Information
- Prerequisites for BGP PA Output Interface Accounting
- Restrictions for BGP PA Output Interface Accounting
- Information About BGP PA Output Interface Accounting
- How to Configure BGP PA Output Interface Accounting
- Configuration Examples for BGP PA Output Interface Accounting
- Where to Go Next
- Additional References
- Command Reference
- Glossary
BGP Policy Accounting Output Interface Accounting
Border Gateway Protocol (BGP) policy accounting (PA) measures and classifies IP traffic that is sent to, or received from, different peers. Policy accounting was previously available on an input interface only. The BGP Policy Accounting Output Interface Accounting feature introduces several extensions to enable BGP PA on an output interface and to include accounting based on a source address for both input and output traffic on an interface. Counters based on parameters such as community list, autonomous system number, or autonomous system path are assigned to identify the IP traffic.
Feature History for BGP PA Output Interface Accounting
| Release |
Modification |
|---|---|
| 12.0(9)S |
This feature was introduced. |
| 12.0(17)ST |
This feature was integrated into Cisco IOS Release 12.0(17)ST. |
| 12.0(22)S |
Output interface accounting was added, and the bucket size was increased. |
| 12.3(4)T |
This feature was integrated into Cisco IOS Release 12.3(4)T. |
| 12.2(22)S |
This feature was integrated into Cisco IOS Release 12.2(22)S. |
- Finding Feature Information
- Prerequisites for BGP PA Output Interface Accounting
- Restrictions for BGP PA Output Interface Accounting
- Information About BGP PA Output Interface Accounting
- How to Configure BGP PA Output Interface Accounting
- Configuration Examples for BGP PA Output Interface Accounting
- Where to Go Next
- Additional References
- Command Reference
- Glossary
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the Feature Information Table at the end of this document.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for BGP PA Output Interface Accounting
Before using the BGP Policy Accounting Output Interface Accounting feature, you must enable BGP and Cisco Express Forwarding or distributed CEF on the router.
Restrictions for BGP PA Output Interface Accounting
The CISCO-BGP-POLICY-ACCOUNTING-MIB is only available in the Cisco IOS Release 12.0(9)S, 12.0(17)ST, 12.2(22)S, and later releases. This MIB is not available on any mainline and T-train release.
Information About BGP PA Output Interface Accounting
BGP PA Output Interface Accounting
Policy accounting using BGP measures and classifies IP traffic that is sent to, or received from, different peers. Originally, BGP PA was available on an input interface only. BGP PA output interface accounting introduces several extensions to enable BGP PA on an output interface and to include accounting based on a source address for both input and output traffic on an interface. Counters based on parameters such as community list, autonomous system number, or autonomous system path are assigned to identify the IP traffic.
Using the BGP table-map command, prefixes added to the routing table are classified by BGP attribute, autonomous system number, or autonomous system path. Packet and byte counters are incremented per input or output interface. A Cisco policy-based classifier maps the traffic into one of eight possible buckets that represent different traffic classes.
Using BGP PA, you can account for traffic according to its origin or the route it traverses. Service providers (SPs) can identify and account for all traffic by customer and can bill accordingly. In the figure below, BGP PA can be implemented in Router A to measure packet and byte volumes in autonomous system buckets. Customers are billed appropriately for traffic that is routed from a domestic, international, or satellite source.
| Figure 1 | Sample Topology for BGP Policy Accounting |
BGP policy accounting using autonomous system numbers can be used to improve the design of network circuit peering and transit agreements between Internet service providers (ISPs).
Benefits of BGP PA Output Interface Accounting
Accounting for IP Traffic Differentially
BGP policy accounting classifies IP traffic by autonomous system number, autonomous system path, or community list string, and increments packet and byte counters. Policy accounting can also be based on the source address. Service providers can account for traffic and apply billing according to the origin of the traffic or the route that specific traffic traverses.
Efficient Network Circuit Peering and Transit Agreement Design
Implementing BGP policy accounting on an edge router can highlight potential design improvements for peering and transit agreements.
How to Configure BGP PA Output Interface Accounting
- Specifying the Match Criteria for BGP PA
- Classifying the IP Traffic and Enabling BGP PA
- Verifying BGP Policy Accounting
Specifying the Match Criteria for BGP PA
The first task in configuring BGP PA is to specify the criteria that must be matched. Community lists, autonomous system paths, or autonomous system numbers are examples of BGP attributes that can be specified and subsequently matched using a route map. Perform this task to specify the BGP attribute to use for BGP PA and to create the match criteria in a route map.
DETAILED STEPS
Classifying the IP Traffic and Enabling BGP PA
After a route map has been defined to specify match criteria, you must configure a way to classify the IP traffic before enabling BGP policy accounting.
Using the table-map command, BGP classifies each prefix that it adds to the routing table according to the match criteria. When the bgp-policy accounting command is configured on an interface, BGP policy accounting is enabled.
Perform this task to classify the IP traffic and enable BGP policy accounting.
DETAILED STEPS
Verifying BGP Policy Accounting
Perform this task to verify that BGP policy accounting is operating.
DETAILED STEPS
| Step 1 | show ip cef [network[mask]] [detail] Enter the show ip cef command with the detail keyword to learn which accounting bucket is assigned to a specified prefix. In this example, the output is displayed for the prefix 192.168.5.0. It shows that accounting bucket number 4 (traffic_index 4) is assigned to this prefix. Example:
Router# show ip cef 192.168.5.0 detail
192.168.5.0/24, version 21, cached adjacency to POS7/2
0 packets, 0 bytes, traffic_index 4
via 10.14.1.1, 0 dependencies, recursive
next hop 10.14.1.1, POS7/2 via 10.14.1.0/30
valid cached adjacency
|
| Step 2 | show ip bgp [network] [network-mask] [longer-prefixes] Enter the show ip bgp command for the same prefix used in Step 1--192.168.5.0--to learn which community is assigned to this prefix. In this example, the output is displayed for the prefix 192.168.5.0. It shows that the community of 100:197 is assigned to this prefix. Example:
Router# show ip bgp 192.168.5.0
BGP routing table entry for 192.168.5.0/24, version 2
Paths: (1 available, best #1)
Not advertised to any peer
100
10.14.1.1 from 10.14.1.1 (32.32.32.32)
Origin IGP, metric 0, localpref 100, valid, external, best
Community: 100:197
|
| Step 3 | show cef interface [type number] policy-statistics[input| output] Enter the show cef interface policy-statistics command to display the per-interface traffic statistics. In this example, the output shows the number of packets and bytes that have been assigned to each accounting bucket: Example:
Router# show cef interface policy-statistics input
FastEthernet1/0/0 is up (if_number 6)
Corresponding hwidb fast_if_number 6
Corresponding hwidb firstsw->if_number 6
BGP based Policy accounting on input is enabled
Index Packets Bytes
1 9999 999900
2 0 0
3 0 0
4 0 0
5 0 0
6 0 0
7 0 0
8 0 0
9 0 0
10 0 0
11 0 0
12 0 0
13 0 0
14 0 0
15 0 0
16 0 0
17 0 0
18 0 0
19 0 0
20 0 0
21 0 0
22 0 0
23 0 0
24 0 0
25 0 0
26 0 0
27 0 0
28 0 0
29 0 0
30 0 0
31 0 0
32 0 0
33 0 0
34 1234 123400
35 0 0
36 0 0
37 0 0
38 0 0
39 0 0
40 0 0
41 0 0
42 0 0
43 0 0
44 0 0
45 1000 100000
46 0 0
47 0 0
48 0 0
49 0 0
50 0 0
51 0 0
52 0 0
53 0 0
54 5123 1198782
55 0 0
56 0 0
57 0 0
58 0 0
59 0 0
60 0 0
61 0 0
62 0 0
63 0 0
64 0 0
|
| Step 4 | show cef interface [type number] [statistics] [detail] Enter the show cef interfaceEXEC command to display the state of BGP policy accounting on a specified interface. In this example, the output shows that BGP policy accounting has been configured to be based on input traffic at Fast Ethernet interface 1/0/0: Example:
Router# show cef interface Fast Ethernet 1/0/0
FastEthernet1/0/0 is up (if_number 6)
Corresponding hwidb fast_if_number 6
Corresponding hwidb firstsw->if_number 6
Internet address is 10.1.1.1/24
ICMP redirects are always sent
Per packet load-sharing is disabled
IP unicast RPF check is disabled
Inbound access list is not set
Outbound access list is not set
IP policy routing is disabled
BGP based policy accounting on input is enabled
BGP based policy accounting on output is disabled
Hardware idb is FastEthernet1/0/0 (6)
Software idb is FastEthernet1/0/0 (6)
Fast switching type 1, interface type 18
IP Distributed CEF switching enabled
IP Feature Fast switching turbo vector
IP Feature CEF switching turbo vector
Input fast flags 0x100, Output fast flags 0x0, Flags 0x0
ifindex 7(7)
Slot 1 Slot unit 0 VC -1
Transmit limit accumulator 0xE8001A82 (0xE8001A82)
IP MTU 1500 |
Configuration Examples for BGP PA Output Interface Accounting
- Specifying the Match Criteria for BGP Policy Accounting Example
- Classifying the IP Traffic and Enabling BGP Policy Accounting Example
Specifying the Match Criteria for BGP Policy Accounting Example
In the following example, BGP communities are specified in community lists, and a route map named set_bucket is configured to match each of the community lists to a specific accounting bucket using the set traffic-index command:
ip community-list 30 permit 100:190 ip community-list 40 permit 100:198 ip community-list 50 permit 100:197 ip community-list 60 permit 100:296 ! route-map set_bucket permit 10 match community-list 30 set traffic-index 2 ! route-map set_bucket permit 20 match community-list 40 set traffic-index 3 ! route-map set_bucket permit 30 match community-list 50 set traffic-index 4 ! route-map set_bucket permit 40 match community-list 60 set traffic-index 5
Classifying the IP Traffic and Enabling BGP Policy Accounting Example
In the following example, BGP policy accounting is enabled on POS interface 2/0/0. The policy accounting criteria is based on the source address of the input traffic, and the table-map command is used to modify the bucket number when the IP routing table is updated with routes learned from BGP.
router bgp 65000 table-map set_bucket network 10.15.1.0 mask 255.255.255.0 neighbor 10.14.1.1 remote-as 65100 ! ip classless ip bgp-community new-format ! interface POS2/0/0 ip address 10.15.1.2 255.255.255.0 bgp-policy accounting input source no keepalive crc 32 clock source internal
Where to Go Next
Additional BGP, CEF, and dCEF command and configuration information is available from the appropriate Cisco IOS command reference or configuration guide documents. For more details, see the "Additional References" section.
Additional References
The following sections provide references related to BGP policy accounting.
Related Documents
| Related Topic |
Document Title |
|---|---|
| BGP commands: complete command syntax, command mode, defaults, usage guidelines, and examples |
Cisco IOS IP Routing: BGP Command Reference |
| Switching commands: complete command syntax, command mode, defaults, usage guidelines, and examples |
Cisco IOS IP Switching Command Reference |
| CEF and dCEF configuration information |
"Cisco Express Forwarding Overview" module |
Standards
| Standards |
Title |
|---|---|
| No new or modified standards are supported by this feature, and support for existing standards has not been modified by this feature. |
-- |
MIBs
RFCs
| RFCs |
Title |
|---|---|
| No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature. |
-- |
Technical Assistance
| Description |
Link |
|---|---|
| The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
Command Reference
The following commands are introduced or modified in the feature or features documented in this module. For information about these commands, see the Cisco IOS IP Routing: BGP Command Reference. For information about all Cisco IOS commands, go to the Command Lookup Tool at http://tools.cisco.com/Support/CLILookup or to the Cisco IOS Master Commands List.
Glossary
AS --autonomous system. An IP term to describe a routing domain that has its own independent routing policy and is administered by a single authority.
BGP --Border Gateway Protocol. Interdomain routing protocol that exchanges reachability information with other BGP systems.
CEF --Cisco Express Forwarding.
dCEF --distributed Cisco Express Forwarding.
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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