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Table Of Contents
Multilink Frame Relay FRF.16.1
Prerequisites for Multilink Frame Relay FRF.16.1
Restrictions for Multilink Frame Relay FRF.16.1
Information About Multilink Frame Relay FRF.16.1
Benefits of Multilink Frame Relay FRF.16.1
Link Integrity Protocol Control Messages
Variable Bandwidth Class Support
Load Balancing with Multilink Frame Relay FRF.16.1
How to Enable Multilink Frame Relay FRF.16.1
Configuring a Multilink Frame Relay Bundle
Configuring a Multilink Frame Relay Bundle Link
Monitoring and Maintaining Multilink Frame Relay FRF.16.1
Configuration Examples for Multilink Frame Relay FRF.16.1
Configuring Multilink Frame Relay: Example
Configuring Variable Bandwidth Class Support: Example
Feature Information for Multilink Frame Relay FRF.16.1
Multilink Frame Relay FRF.16.1
First Published: May 14, 2001Last Updated: August 08, 2010The Multilink Frame Relay (FRF.16.1) feature introduces functionality based on the Frame Relay Forum Multilink Frame Relay UNI/NNI Implementation Agreement (FRF.16.1). This feature provides a cost-effective way to increase bandwidth for particular applications by enabling multiple serial links to be aggregated into a single bundle of bandwidth. Multilink Frame Relay (MFR) is supported on User-to-Network Interfaces (UNI) and Network-to-Network Interfaces (NNI) in Frame Relay networks.
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 for Multilink Frame Relay FRF.16.1" section.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for Multilink Frame Relay FRF.16.1
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Restrictions for Multilink Frame Relay FRF.16.1
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Information About Multilink Frame Relay FRF.16.1
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How to Enable Multilink Frame Relay FRF.16.1
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Configuration Examples for Multilink Frame Relay FRF.16.1
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Feature Information for Multilink Frame Relay FRF.16.1
Prerequisites for Multilink Frame Relay FRF.16.1
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Multilink Frame Relay must be configured on the peer device.
Restrictions for Multilink Frame Relay FRF.16.1
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ISDN interfaces and any type of virtual interface cannot be a bundle link.
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Frame Relay fragmentation (FRF.12) is not supported in Cisco IOS releases 12.0(17)S, 12.2(8)T, and 12.2(14)S.
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The multilink Frame Relay MIB (RFC 3020) is not supported.
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FRF.9 hardware compression over multilink Frame Relay is not supported.
Information About Multilink Frame Relay FRF.16.1
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Benefits of Multilink Frame Relay FRF.16.1
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Link Integrity Protocol Control Messages
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Variable Bandwidth Class Support
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Load Balancing with Multilink Frame Relay FRF.16.1
Benefits of Multilink Frame Relay FRF.16.1
Flexible Pool of Bandwidth
By combining multiple physical interfaces into a bundle, you can design a Frame Relay interface that has more bandwidth than is available from any single physical interface. For example, many new network applications require more bandwidth than is available on a T1 line. One option is to invest in a T3 line; however, T3 lines can be expensive and are not available in some locations. Multilink Frame Relay provides a cost-effective solution to this problem by allowing multiple T1 lines to be aggregated into a single bundle of bandwidth.
Greater Service Resilience When Links Fail
Greater service resilience is provided when multiple physical interfaces are provisioned as a single bundle. When a link fails, the bundle continues to support the Frame Relay service by transmitting across the remaining bundle links.
Link Integrity Protocol Control Messages
For link management, each end of a bundle link follows the MFR Link Integrity Protocol and exchanges link-control messages with its peer (the other end of the bundle link). For a bundle link to be brought up, each end of the link must complete an exchange of ADD_LINK and ADD_LINK_ACK messages. To maintain the link, both ends periodically initiate the exchange of HELLO and HELLO_ACK messages. This exchange of hello messages and acknowledgments serves as a keepalive mechanism for the link. If a router is sending hello messages but not receiving acknowledgments, it will resend the hello message up to a configured maximum number of times. If the router exhausts the maximum number of retries, the bundle link line protocol is considered down (nonoperational).
The bundle link interface's line protocol status is considered up (operational) when the peer device acknowledges that it will use the same link for the bundle. The line protocol remains up when the peer device acknowledges the hello messages from the local router.
The bundle interface's line protocol status is considered up when the Frame Relay data-link layer at the local router and peer device is synchronized using the Local Management Interface (LMI), when LMI is enabled. The bundle line protocol remains up as long as the LMI keepalives are successful.
Variable Bandwidth Class Support
Multilink Frame Relay (FRF.16.1) variable bandwidth class support allows you to specify the criterion used to activate or deactivate a Frame Relay bundle. Consistent with the Frame Relay Forum Multilink Frame Relay UNI/NNI Implementation Agreement (FRF.16.1), bandwidth classes A (single link), B (all links), and C (threshold) are supported.
Class A (Single Link)
The Frame Relay bundle is provisioned when one or more bundle links indicate by issuing a BL_ACTIVATE message that operational bandwidth is available. When this occurs, the bundle emulates a physical link by issuing a PH_ACTIVATE message to the data-link layer.
When the operational bandwidth of a bundle link fails to meet operational requirements (for instance, if it is in rollback mode), the bundle link issues a BL_DEACTIVATE message. When all bundle links are down in a class A bundle, a PH_DEACTIVATE message is sent to the data-link layer, indicating that the Frame Relay bundle cannot accept frames.
Class B (All Links)
The Frame Relay bundle is provisioned when all bundle links indicate by issuing a BL_ACTIVATE message that operational bandwidth is available. When this occurs, the bundle emulates a physical link by issuing a PH_ACTIVATE message to the data-link layer.
When the operational bandwidth of a bundle link fails to meet operational requirements (for instance, if it is in loopback mode), the bundle link issues a BL_DEACTIVATE message. When any bundle link is down in a class B bundle, a PH_DEACTIVATE message is sent to the data-link layer, indicating that the Frame Relay bundle cannot accept frames.
Class C (Threshold)
The Frame Relay bundle is provisioned when the minimum number of links in the configured bundle issue a BL_ACTIVATE message. When this occurs, the bundle emulates a physical link by issuing a PH_ACTIVATE message to the data-link layer.
When the number of bundle links that are issuing a BL_ACTIVATE message falls below the configured threshold value, a PH_DEACTIVATE message is sent to the data-link layer, indicating that the Frame Relay bundle cannot accept frames.
Load Balancing with Multilink Frame Relay FRF.16.1
Multilink Frame Relay provides load balancing across the bundle links within a bundle. If a bundle link chosen for transmission happens to be busy transmitting a long packet, the load-balancing mechanism can try another link, thus solving the problems seen when delay-sensitive packets have to wait.
How to Enable Multilink Frame Relay FRF.16.1
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Configuring a Multilink Frame Relay Bundle
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Configuring a Multilink Frame Relay Bundle Link
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Monitoring and Maintaining Multilink Frame Relay FRF.16.1
Configuring a Multilink Frame Relay Bundle
To configure the bundle interface for multilink Frame Relay, perform the steps in this section.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
interface mfr interface-number
4.
frame-relay multilink bandwidth-class [a | b | c [threshold]]
5.
frame-relay intf-type dce
6.
frame-relay multilink bid name
7.
frame-relay multilink output-threshold bytes
8.
interface mfr interface-number.subinterface-number point-to-point
9.
ip address ip-address mask
10.
frame-relay interface-dlci dlci
11.
end
12.
show frame-relay multilink
DETAILED STEPS
Configuring a Multilink Frame Relay Bundle Link
To configure a bundle link interface for multilink Frame Relay, perform the steps in this section.
Tip
To minimize latency that results from the arrival order of packets, we recommend bundling physical links of the same line speed in one bundle.
SUMMARY STEPS
1.
enable
2.
configure terminal
3.
interface serial number
4.
encapsulation frame-relay mfr number [name]
5.
frame-relay multilink output-threshold bytes
6.
frame-relay multilink lid name
7.
frame-relay multilink hello seconds
8.
frame-relay multilink ack seconds
9.
frame-relay multilink retry number
10.
end
11.
show frame-relay multilink
DETAILED STEPS
Monitoring and Maintaining Multilink Frame Relay FRF.16.1
To monitor and maintain multilink Frame Relay, perform the steps in this section.
SUMMARY STEPS
1.
enable
2.
debug frame-relay multilink [control [mfr number | serial number]]
3.
show frame-relay multilink [mfr number | serial number] [detailed]
4.
show interfaces mfr number
DETAILED STEPS
Examples
The following example shows output for the show frame-relay multilink command. Because a particular bundle or bundle link is not specified, information for all bundles and bundle links is displayed:
Router# show frame-relay multilinkBundle: MFR0, state up, class A, no fragmentationID: Bundle-DallasSerial5/1, state up/up, ID: BL-Dallas-1Serial5/3, state up/add-sent, ID: BL-Dallas-3Bundle: MFR1, state down, class B, fragmentationID: Bundle-NewYork#1Serial3/0, state up/up, ID: BL-NewYork-1Serial3/2, state admin-down/idle, ID: BL-NewYork-2The following example shows output for the show frame-relay multilink command when a Frame Relay bundle is configured as bandwidth class C (threshold):
Router# show frame-relay multilinkBundle: MFR0, state down, class C (threshold 3), no fragmentationID: Bundle-DallasSerial5/1, state up/up, ID: BL-Dallas-1Serial5/3, state up/add-sent, ID: BL-Dallas-3The following example shows output for the show frame-relay multilink command when the serial number keyword and argument are specified. It displays information about the specified bundle link:
Router# show frame-relay multilink serial 3/2Bundle links :Serial3/2, HW state :down, Protocol state :Down_idle, LID :Serial3/2Bundle interface = MFR0, BID = MFR0The following examples show output for the show frame-relay multilink command when the serial number keyword and argument and the detailed option are specified. Detailed information about the specified bundle links is displayed. The first example shows a bundle link in the "idle" state. The second example shows a bundle link in the "up" state:
Router# show frame-relay multilink serial 3 detailBundle links:Serial3, HW state = up, link state = Idle, LID = Serial3Bundle interface = MFR0, BID = MFR0Cause code = none, Ack timer = 4, Hello timer = 10,Max retry count = 2, Current count = 0,Peer LID = Serial5/3, RTT = 0 msStatistics:Add_link sent = 0, Add_link rcv'd = 10,Add_link ack sent = 0, Add_link ack rcv'd = 0,Add_link rej sent = 10, Add_link rej rcv'd = 0,Remove_link sent = 0, Remove_link rcv'd = 0,Remove_link_ack sent = 0, Remove_link_ack rcv'd = 0,Hello sent = 0, Hello rcv'd = 0,Hello_ack sent = 0, Hello_ack rcv'd = 0,outgoing pak dropped = 0, incoming pak dropped = 0Router# show frame-relay multilink serial 3 detailBundle links:Serial3, HW state = up, link state = Up, LID = Serial3Bundle interface = MFR0, BID = MFR0Cause code = none, Ack timer = 4, Hello timer = 10,Max retry count = 2, Current count = 0,Peer LID = Serial5/3, RTT = 4 msStatistics:Add_link sent = 1, Add_link rcv'd = 20,Add_link ack sent = 1, Add_link ack rcv'd = 1,Add_link rej sent = 19, Add_link rej rcv'd = 0,Remove_link sent = 0, Remove_link rcv'd = 0,Remove_link_ack sent = 0, Remove_link_ack rcv'd = 0,Hello sent = 0, Hello rcv'd = 1,Hello_ack sent = 1, Hello_ack rcv'd = 0,outgoing pak dropped = 0, incoming pak dropped = 0Configuration Examples for Multilink Frame Relay FRF.16.1
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Configuring Multilink Frame Relay: Example
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Configuring Variable Bandwidth Class Support: Example
Configuring Multilink Frame Relay: Example
The following example shows the configuration of bundle "MFR1." Serial interfaces 5/0 and 6/0 are configured as bundle links:
interface MFR1no ip addressmls qos trust dscpframe-relay intf-type dceframe-relay multilink bid router1!interface MFR1.1 point-to-pointip address 10.0.1.1 255.255.255.0ip pim sparse-modemls qos trust dscpframe-relay interface-dlci 100interface Serial5/0encapsulation frame-relay MFR1frame-relay multilink lid first-linkframe-relay multilink hello 9frame-relay multilink retry 3interface Serial6/0encapsulation frame-relay MFR1frame-relay multilink ack 4Configuring Variable Bandwidth Class Support: Example
The following example configures the Frame Relay bundle "MFR1" to use the class B (all links) criterion to be activated or deactivated:
interface MFR1ip address 10.1.1.1 255.255.255.0frame-relay interface-dlci 100frame-relay multilink bandwidth-class bAdditional References
Related Documents
Standards
MIBs
MIB MIBs LinkNone
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
RFCs
Technical Assistance
Feature Information for Multilink Frame Relay FRF.16.1
Table 1 lists the features in this module and provides links to specific configuration information.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note
Table 1 lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Table 1 Feature Information for Multilink Frame Relay (FRF.16.1)
Feature Name Releases Feature InformationMultilink Frame Relay (FRF.16.1)
12.0(17)S
12.2(8)T
12.2(14)S
12.2(28)SB
12.2(33)SRA
12.2(31)SB2
12.2(33)SXHThe Multilink Frame Relay (FRF.16.1) feature introduces functionality based on the Frame Relay Forum Multilink Frame Relay UNI/NNI Implementation Agreement (FRF.16.1).
In 12.0(17)S, This feature was introduced on the Cisco 12000 series.
The following sections provide information about this feature:
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Information About Multilink Frame Relay FRF.16.1
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How to Enable Multilink Frame Relay FRF.16.1
The following commands were introduced or modified: debug frame-relay multilink, encapsulation frame-relay mfr, frame-relay multilink ack, frame-relay multilink bandwidth-class, frame-relay multilink bid, frame-relay multilink hello, frame-relay multilink lid, frame-relay multilink output-threshold, frame-relay multilink retry, interface mfr, show frame-relay multilink.
Frame Relay fragmentation (FRF.12)
12.3(9)
12.3(11)T
12.2(30)SFrame Relay Fragmentation based upon FRF.12 allow long data frames to be fragmented into smaller pieces and interleaved with real-time voice frames or other delay-sensitive traffic.
In 12.3(9), this feature was introduced.
Multilink Frame Relay (FRF.16.1) - Variable Bandwidth Class
12.0(30)S
12.4(2)T
15.0(1)SMultilink Frame Relay (FRF.16.1) variable bandwidth class support allows you to specify the criterion used to activate or deactivate a Frame Relay bundle.
In 12.0(30)S, this feature was introduced.
The following sections provide information about this feature:
Glossary
BID—Bundle identification. The BID is the name used to identify the bundle. The BID can be assigned, or the default can be used.
BL_ACTIVATE—A message that controls the addition of a bundle link to a Frame Relay bundle.
BL_DEACTIVATE—A message that controls the removal a bundle link from a Frame Relay bundle.
bundle—A logical grouping of one or more physical interfaces using the formats and procedures of multilink Frame Relay. A bundle emulates a physical interface to the Frame Relay data-link layer. The bundle is also referred to as the MFR interface.
bundle link—An individual physical interface that is a member of a bundle.
DLCI—data-link connection identifier. A value that identifies a permanent virtual circuit (PVC) in a Frame Relay network.
HELLO message—A message that notifies a peer endpoint that the local endpoint is in the operational state (up).
HELLO_ACK—A message that notifies a peer endpoint that a hello message has been received.
LID—link identification. The LID is the name used to identify a bundle link. The LID can be assigned, or the default can be used.
LMI—Local Management Interface. A set of enhancements to the basic Frame Relay specification. LMI includes support for a keepalive mechanism, which verifies that data is flowing; a multicast mechanism, which provides the network server with its local DLCI and the multicast DLCI; global addressing, which gives DLCIs global rather than local significance in Frame Relay networks; and a status mechanism, which provides an ongoing status report on the DLCIs known to the switch.
NNI—Network-to-Network Interface. The interface between two Frame Relay devices that are both located in a private network or both located in a public network.
PH_ACTIVATE—A message that indicates that the Frame Relay bundle is up.
PH_DEACTIVATE—A message that indicates that the Frame Relay bundle is down.
UNI—User-to-Network Interface. The interface between a Frame Relay device in a public network and a Frame Relay device in a private network.
Cisco and the Cisco Logo are trademarks of Cisco Systems, Inc. and/or its affiliates in the U.S. and other countries. A listing of Cisco's trademarks can be found at www.cisco.com/go/trademarks. Third party trademarks mentioned are the property of their respective owners. The use of the word partner does not imply a partnership relationship between Cisco and any other company. (1005R)
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
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