NBAR is a classification engine that recognizes and classifies a wide variety of protocols and applications, including web-based and other difficult-to-classify applications and protocols that use dynamic TCP/UDP port assignments.

When NBAR recognizes and classifies a protocol or an application, the network can be configured to apply the appropriate QoS for that application or traffic with that protocol. The QoS is applied using the MQC.

Note	For more information about the MQC, see the “Applying QoS Features Using the MQC” module.

NBAR introduces several classification features that identify applications and protocols from Layer 4 through Layer 7. These classification features are as follows:

• Statically assigned TCP and UDP port numbers.

• Non-TCP and non-UDP IP protocols.

• Dynamically assigned TCP and UDP port numbers. This kind of classification requires stateful inspection, that is, the ability to inspect a protocol across multiple packets during packet classification.

• Subport classification or classification based on deep packet inspection, that is, classification for inspecting packets.

Note	Access Control Lists (ACLs) can also be used for classifying static port protocols. However, NBAR is easier to configure and can provide classification statistics that are not available when ACLs are used.

NBAR includes a Protocol Discovery feature that provides an easy way to discover application protocols that are operating on an interface. For more information about Protocol Discovery, see the “Enabling Protocol Discovery” module.

Note	NBAR classifies network traffic by application or protocol. Network traffic can be classified without using NBAR. For information about classifying network traffic without using NBAR, see the “Classifying Network Traffic” module.

NBAR includes the Protocol Pack feature that provides an easy way to load protocols and helps NBAR recognize additional protocols for network traffic classification. A protocol pack is set a of protocols developed and packed together. A new protocol pack can be loaded on the device to replace the default IOS protocol pack that is already present in the device.

Identifying and classifying network traffic is an important first step in implementing QoS. A network administrator can more effectively implement QoS in a networking environment after identifying the number and types of applications and protocols that are running on a network.

NBAR gives network administrators the ability to see the different types of protocols and the amount of traffic generated by each protocol. After NBAR gathers this information, users can organize traffic into classes. These classes can then be used to provide different levels of service for network traffic, thereby allowing better network management by providing the appropriate level of network resources for the network traffic.

NBAR is also used in Cisco Application Visibility and Control (AVC). With AVC, NBAR provides better application performance through better QoS and policing, and provides finer visibility about the network that is being used.

NBAR can classify Citrix Independent Computing Architecture (ICA) traffic and perform subport classification of Citrix traffic based on the published application name or ICA tag number.

Real-time Transport Protocol (RTP) is a packet format for multimedia data streams. It can be used for media-on-demand and for interactive services such as Internet telephony. RTP consists of a data part and a control part. The control part is called Real-Time Transport Control Protocol (RTCP). RTCP is a separate protocol that is supported by NBAR. It is important to note that the NBAR RTP Payload Type Classification feature does not identify RTCP packets and that RTCP packets run on odd-numbered ports and RTP packets run on even-numbered ports.

The data part of RTP is a thin protocol that provides support for applications with real-time properties such as continuous media (audio and video), which includes timing reconstruction, loss detection, and security and content identification. RTP is discussed in RFC 1889 (A Transport Protocol for Real-Time Applications ) and RFC 1890 (RTP Profile for Audio and Video Conferences with Minimal Control ).

The RTP payload type is the data transported by RTP in a packet, for example, audio samples or compressed video data.

The NBAR RTP Payload Type Classification feature not only allows real-time audio and video traffic to be statefully identified, but can also differentiate on the basis of audio and video codecs to provide more granular QoS. The RTP Payload Type Classification feature, therefore, does a deep-packet inspection into the RTP header to classify RTP packets.

For more information on the classification of RTP with NBAR, see NBAR RTP Payload Classification.

NBAR supports the use of custom protocols to identify custom applications. Custom protocols support static port-based protocols and applications that NBAR does not currently support. You can add to the set of protocols and application types that NBAR recognizes by creating custom protocols.

Custom protocols extend the capability of NBAR Protocol Discovery to classify and monitor additional static port applications and allow NBAR to classify nonsupported static port traffic.

Once the custom protocols are defined, you can then use them with the help of NBAR Protocol Discovery and the MQC to classify the traffic.

With NBAR supporting the use of custom protocols, NBAR can map static TCP and UDP port numbers to the custom protocols.

There are two types of custom protocols:

• Predefined custom protocols

• User-defined custom protocols

NBAR includes the following characteristics related to predefined custom protocols and applications:

• Custom protocols have to be named custom-xx, with xx being a number.

• Ten custom applications can be assigned using NBAR, and each custom application can have up to 16 TCP and 16 UDP ports each mapped to the individual custom protocol. The real-time statistics of each custom protocol can be monitored using Protocol Discovery.

• After creating a variable when creating a custom protocol, you can use the match protocol command to classify traffic on the basis of a specific value in the custom protocol.

NBAR includes the following characteristics related to user-defined custom protocols and applications:

• The ability to inspect the payload for certain matching string patterns at a specific offset.

• The ability to allow users to define the names of their custom protocol applications. The user-named protocol can then be used by Protocol Discovery, the Protocol Discovery MIB, and the match protocol command as an NBAR-supported protocol.

• The ability of NBAR to inspect custom protocols specified by traffic direction (that is, traffic heading toward a source or destination rather than traffic in both directions), if desired by the user.

• CLI support that allows a user configuring a custom application to specify a range of ports rather than to specify each port individually.

• The variable keyword, the field-name argument, and the field-length argument were added to the ip nbar custom command.

• The http keyword group that lets you add custom host and URL signatures.

This additional keyword and two additional arguments allow for creation of more than one custom protocol based on the same port numbers.

Note	Defining a user-defined custom protocol restarts the NBAR feature, whereas defining predefined custom protocol does not restart the NBAR feature.

NBAR can improve traffic classification by using DNS transaction information exchanged when a user initiates a connection with an application server. This method offers the significant advantage of classifying flows from the first packet in the flow.

To illustrate, when a web-based application is opened in a browser, the browser first communicates with a DNS server to request the IP address of the relevant server for the application. The DNS transaction consists of a request and response; the response contains the IP address of the server for the web-based application.

Using information from this transaction, NBAR can correctly associate the web-based application with the relevant server IP address. NBAR can then identify future traffic involving that IP address from the first packet of the flow.

Dynamic Packet Description Language Modules (PDLMs) allow new protocol support or enhance existing protocol support for NBAR without the requirement of a specific Cisco release upgrade and device reload. If the support is for enhancing protocols for NBAR, the module version of the PDLMs should be greater than the existing version of the PDLMs. Subsequent Cisco releases incorporate support for these new protocols.

Note	PDLMs must be loaded on both Route Processors (RPs) when using the ASR 1006 redundant hardware setup.

Dynamic PDLMs are platform-specific and have a Software Family Identifier (SFI) embedded in them. Dynamic PDLMs of other platforms cannot be loaded on Cisco ASR 1000 Series Aggregation Services Routers.

The match protocol (NBAR) command is used to classify traffic on the basis of protocols supported by NBAR. NBAR is can classify the following types of protocols:

• Non-UDP and non-TCP IP protocols

• TCP and UDP protocols that use statically assigned port numbers

• TCP and UDP protocols that use statically assigned port numbers but still require stateful inspection

• TCP and UDP protocols that dynamically assign port numbers and therefore require stateful inspection

To view the list of protocols supported in a protocol pack, see NBAR Protocol Library.

The NBAR2 Protocol Pack provides an easy way to update protocols supported by NBAR2 without replacing the base IOS image that is already present in the device. A Protocol Pack is a set of protocols developed and packaged together. To view the list of protocols supported in a Protocol Pack, see NBAR2 Protocol Library.

The following applications are the most common peer-to-peer file-sharing applications supported by NBAR:

• BitTorrent

• DirectConnect

• eDonkey

• eMule

• FastTrack

• KazaA (and KazaA Lite and KazaA Lite Resurrection)

• Win MX

• POCO

DirectConnect and eDonkey P2P protocols support the following subclassifications depending on your release:

• eDonkey supports the following subclassification options:

  • file-transfer
  • search-file-name
  • text-chat

• KazaA, FastTrack, and Gnuetella support the file-transfer subclassification.

The Gnutella file sharing became classifiable using NBAR in Cisco IOS XE Release 2.5.

Applications that use the Gnutella protocol are Bearshare, Gnewtellium, Gnucleus, Gtk-Gnutella, Limewire, Mutella, Phex, Qtella, Swapper, and Xolo. The traffic from the applications that use the Gnutella protocol will be classified as Gnutella and not as the respective application.

NBAR supports a wide range of stateful network protocols such as HTTP classification by URL, Host and MIME type, FTP, TFTP, and so on. NBAR classifies static-port protocols such as those classifiable with access control lists (ACLs).

Multi stage classification reports the underlying protocol as a temporary classification instead of an unknown classification. For example, in earlier releases, to support cases like Video-over-HTTP, where the signature is found on the HTTP response packet, recursive classification over HTTP was allowed causing the first packet of HTTP flows to be reported as unknown, which in turn impacted the following:

• Protocol discovery—reduced classification.

• Packet-based flexible NetFlow (FNF)—reduced classification.

• QoS—delayed classification.

• Performance—because more packets were being processed.

• Aging short flows that are in the middle of a classification process stops without any classification results, although they were partially classified.

Prior to NBAR multi stage classification, NBAR reported an unknown classification result until a final classification decision was reached. NBAR multi stage classification returns the most up-to-date classification decision. It modifies the data path to expose the underlying protocols from media partitioning (MP) recursive classification path—instead of returning “unknown” until a final classification is available, it returns the current (temporary) classification decision.

NBAR multi stage classification has the following characteristics:

Backward incompatibility

If a system has a policy that matches a protocol like SOCKet Secure (SOCKS), which is an underlying protocol for AOL Instant Messenger (AIM) and Bittorrent, when all other protocols have failed (when other protocols are also enabled, either through protocol discovery or through FNF or explicitly through modular QoS CLI [MQC]), this policy would match the first packets of AIM or Bittorrent flows as SOCKS. Blocking the underlying protocol while allowing non underlying protocols is not possible with multi stage classification.

Traffic Reordering

When a user configures different priorities for each classification on the traffic flow, the flow might be directed to different output queues. With multi stage classification more than one classification decision for a single traffic flow may occur. When the traffic is based on prioritized classification, we recommend that the underlying protocols get a higher priority (for example, HTTP get a higher priority than Video-over-HTTP).

Performance Routing (PfR)

When PfR checks the classification from NBAR to make a routing decision, it takes into account if this is a final classification or not. If it is not the final classification, no routing decision is made as it may split the traffic flow to many paths resulting in an “unknown” classification.

NBAR clients let the users know if the classification is temporary or not.

NBAR includes a feature called Protocol Discovery. Protocol discovery provides an easy way to discover protocol packets passing through an interface. For more information about Protocol Discovery, see the “Enabling Protocol Discovery” module.

The NBAR Protocol Discovery MIB expands the capabilities of NBAR Protocol Discovery by providing the following new functionalities through the Simple Network Management Protocol (SNMP):

• Enable or disable Protocol Discovery per interface.

• Display Protocol Discovery statistics.

• Configure and display multiple top-n tables that list protocols by bandwidth usage.

• Configure thresholds based on the traffic of particular NBAR-supported protocols or applications that report breaches and send notifications when these thresholds are exceeded.

For more information about the NBAR Protocol Discovery MIB, see the “Network-Based Application Recognition Protocol Discovery Management Information Base” module.

Depending on your release, NBAR provides the ability to simultaneously search large number of multipacket signatures. This new technique is supported for many of the new protocols. This technique also provides improved performance and accuracy for other protocols. Along with the support for new signatures, the multipacket classification capabilities change NBAR behavior in the following ways:

1. NBAR classification requires anywhere between 1 and 15 payload packets in a flow depending on the protocol. Retransmitted packets are not counted in this calculation.

2. NBAR will neither classify flows without any payload packets nor classify any TCP payload packet with a wrong sequence number even if there are 15 payload packets for classification.

3. TCP retransmitted packets are not counted as valid packets for classification in the Multipacket Engine module. These type of packets can delay the classification until a sufficient number of valid payload packets are accumulated.

4. Payload packets with only static signatures in NBAR are classified after the single-packet and multipacket protocols are processed and failed. Therefore, a maximum of 15 payload packets can be classified as unknown until the final (static) classification decision is taken.

5. Due to the above-mentioned restrictions, custom protocols can be used to force the classification of the first packet, ignoring the existence of payload or correct sequence numbers in the port-based classification.

Depending on your release, the NBAR IPv4 and IPv6 classification on VRF interfaces is supported.

Note	Classification for Citrix protocol with “app” subclassification is not guaranteed on VRF interfaces when NBAR is enabled on VRF interfaces.

Depending on your release, the following types of classification are supported:

• NBAR provides static port-based classification and IP protocol-based classification for IPv6 packets.

• NBAR supports IPv6 classification in protocol discovery mode, but not in MQC mode.

• NBAR always reads the next header field in the fixed IPv6 header to determine the transport layer protocol used by the packet’s payload for IPv6 packets. If an IPv6 packet contains one or more extension headers, NBAR will not skip to the last IPv6 extension header to read the actual protocol type; instead, NBAR classifies the packet as an IPv6 extension header packet.

NBAR supports Group Encrypted Transport VPN (GETVPN). When ingress QoS is in crypto-map mode, the ingress QoS will work on encrypted traffic.

You can go back to backward compatible mode by using the ip nbar disable classification encrypted-app command in global configuration mode.

Note	GETVPN is currently not supported by AVC and FNF.

CAPWAP (Control And Provisioning of Wireless Access Points) is a protocol is used in wireless traffic, providing point-to-point encapsulation (tunnel) for application traffic. There are two types of CAPWAP traffic: data and control.

NBAR provides a CAPWAP recognition mode that enables NBAR classification of the application traffic within a CAPWAP tunnel.

device# config terminal
device(config)# ip nbar classification tunneled-traffic capwap

Useful for policy implementations that do not use SRND. A disadvantage of this method is that it can be difficult to keep track of the mapping between traffic and the categories and sub-categories defined within the policy. For information about the procedure, see Configuring Attribute-based Protocol Match Using Categories and Sub-categories.

The NBAR category/sub-category model can support SRND implementations. However, beginning with the release of IOS 15.5(3)T and IOS XE 3.16S, for SRND policy implementations it is more efficient and recommended to use the SRND-specific model instead.

The SRND-specific model provides two attributes (traffic-class and business-relevance) to configure protocol matching for SRND-based policies. The attributes provided for operation with SRND-based policies are applicable only within the context of SRND implementations.

The following sections show a typical example of a class-map and policy-map for an SRND implementation. It illustrates how the traffic-class and business-relevance attributes address the 12-class SRND QoS model.

class-map match-all VOICE
    match protocol attribute traffic-class voip-telephony
    match protocol attribute business-relevance business-relevant

class-map match-all BROADCAST-VIDEO
    match protocol attribute traffic-class broadcast-video
    match protocol attribute business-relevance business-relevant

class-map match-all INTERACTIVE-VIDEO
    match protocol attribute traffic-class real-time-interactive
    match protocol attribute business-relevance business-relevant

class-map match-all MULTIMEDIA-CONFERENCING
    match protocol attribute traffic-class multimedia-conferencing
    match protocol attribute business-relevance business-relevant

class-map match-all MULTIMEDIA-STREAMING
    match protocol attribute traffic-class multimedia-streaming
    match protocol attribute business-relevance business-relevant

class-map match-all SIGNALING
    match protocol attribute traffic-class signaling
    match protocol attribute business-relevance business-relevant

class-map match-all NETWORK-CONTROL
    match protocol attribute traffic-class network-control
     match protocol attribute business-relevance business-relevant

class-map match-all NETWORK-MANAGEMENT
    match protocol attribute traffic-class ops-admin-mgmt
    match protocol attribute business-relevance business-relevant

class-map match-all TRANSACTIONAL-DATA
    match protocol attribute traffic-class transactional-data
    match protocol attribute business-relevance business-relevant

class-map match-all BULK-DATA
    match protocol attribute traffic-class bulk-data
    match protocol attribute business-relevance business-relevant

class-map match-all SCAVENGER
    match protocol attribute business-relevance business-irrelevant

policy-map 12-cls-marking

class VOICE
    set dscp ef

class BROADCAST-VIDEO
    set dscp cs5

class INTERACTIVE-VIDEO
    set dscp cs4

class MULTIMEDIA-CONFERENCING
    set dscp af41

class MULTIMEDIA-STREAMING
    set dscp af31

class SIGNALING
    set dscp cs3

class NETWORK-CONTROL
    set dscp cs6

class NETWORK-MANAGEMENT
    set dscp cs2

class TRANSACTIONAL-DATA
    set dscp af21

class BULK-DATA
    set dscp af11

class SCAVENGER
    set dscp cs1

class class-default
    set dscp default