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This chapter describes how to configure the Bandwidth Allocation Control Protocol (BACP), described in RFC 2125.
The Bandwidth Allocation Control Protocol provides Multilink PPP peers with the ability to govern link utilization. Once peers have successfully negotiated BACP, they can use the Bandwidth Allocation Protocol (BAP), which is a subset of BACP, to negotiate bandwidth allocation. BAP provides a set of rules governing dynamic bandwidth allocation through call control; a defined method for adding and removing links from a multilink bundle for Multilink PPP is used.
BACP provides the following benefits:
For simplicity, the remaining text of this chapter makes no distinction between BACP and BAP. Only BACP is mentioned.
For a complete description of the PPP BACP commands in this chapter, refer to the "PPP Bandwidth Allocation Control Protocol Commands" chapter of the Dial Solutions Command Reference. To locate documentation of other commands that appear in this chapter, use the command reference master index or search online.
PPP BACP can be configured to operate in the following ways:
A virtual or dialer interface must be configured either to make call requests or to make callback requests, but cannot be configured to do both.
BACP supports only ISDN and asynchronous serial interfaces.
Before you configure BACP on an interface, determine the following important information. The router might be unable to connect to a peer if this information is incorrect.
BACP can be configured on a virtual template interface or on a dialer interface (including dialer rotary groups and ISDN interfaces).
Complete the following steps to configure BACP on a selected interface or interface template:
Step 1 Enable BACP.
Passive mode is in effect and the values of several parameters are set by default when PPP BACP is enabled.
If you can accept all the passive mode parameters, do not go to Step 2.
Step 2 Modify BACP Passive Mode Default Settings
or
You might need to configure a base telephone number, if it is applicable to your dial-in environment. This is a number that remote users can dial to establish a connection. Otherwise, individual PPP BACP links might need numbers. Information is provided in the task lists for configuring passive mode or active mode PPP BACP. See the ppp bap number command options in the task lists.
You can also troubleshoot BACP configuration and operations and monitor interfaces configured for PPP BACP. See the "Troubleshoot BACP" and "Monitor Interfaces Configured for BACP" sections for details.
For examples of PPP BACP configuration, see the "BACP Configuration Examples" section.
To enable PPP bandwidth allocation control and dynamic allocation of bandwidth, use one of the following commands in interface configuration mode:
or ppp multilink bap required Enable PPP BACP bandwidth allocation negotiation. Enable PPP BACP bandwidth allocation negotiation and enforce mandatory negotiation of BACP for the multilink bundle.
Command
Purpose
When PPP BACP is enabled, it is in passive mode by default and the following settings are in effect:
The default settings will be in effect in the environment for which the ppp multilink bap command is entered:
To modify the default parameter values or to configure additional parameters in passive mode, use the following commands, as needed, in interface configuration mode for the interface or virtual template interface that is configured for PPP BACP:
| Command | Purpose |
|---|---|
ppp bap timeout pending seconds | Modify the timeout on pending actions. |
ppp bap timeout response seconds | Modify the timeout on not receiving a response from a peer. |
Modify the number of attempts to call a number. | |
Modify the number of times to send a call status indication. | |
ppp bap max req-retries number | Modify the number of retries of a particular request. |
Modify the maximum number of free dialers logged. | |
Specify that only analog links can be added to a multilink bundle | |
ppp bap number default phone-number | For all DDR-capable interfaces in the group, specify a primary telephone number for the peer to call for PPP BACP negotiation, if different from any base number defined on the dialer interface or virtual template interface. |
ppp bap number secondary phone-number | For BRI interfaces on which a different number is provided for each B channel, specify the secondary telephone number. |
ppp bap drop timer seconds | Specify a time to wait between outgoing link drop requests. |
no ppp bap monitor load | Disable the default monitoring of load and the validation of peer requests against load thresholds. |
To configure active mode BACP, complete the following tasks in interface configuration mode for the dialer interface on which BACP was enabled. For your convenience, the tasks that make BACP function in active mode are presented before the tasks that change default parameters or add parameters.
| Command | Purpose |
|---|---|
| Enable Active Mode |
Enable the interface to initiate the addition of links to the multilink bundle. | |
Enable the interface to initiate the addition of links upon peer request. | |
Enable the interface to drop a link without negotiation after receiving no response to retries to send a drop request. | |
Set the time to wait between outgoing call requests. | |
| Modify Default Settings |
ppp bap timeout pending seconds | Modify the timeout on pending actions. |
ppp bap timeout response seconds | Modify the timeout on not receiving a response from a peer. |
Modify the number of attempts to call a number. | |
Modify the number of times to send a call status indication. | |
ppp bap max req-retries number | Modify the number of retries of a particular request. |
Modify the maximum number of free dialers logged. | |
Specify that only analog links can be added to a multilink bundle | |
ppp bap number default phone-number | For all DDR-capable interfaces in the group, specify a primary telephone number for the peer to call for PPP BACP negotiation, if different from any base number defined on the dialer interface or virtual template interface. |
ppp bap number secondary phone-number | For BRI interfaces on which a different number is provided for each B channel, specify the secondary telephone number. |
To monitor interfaces configured for PPP BACP, use the following commands in EXEC mode:
| Command | Purpose |
|---|---|
show ppp bap group [name] | Display information about all PPP BACP multilink bundle groups or a specific, named multilink bundle group. |
Display information about the BACP queues. | |
Display information about the dialer interface, the multilink bundle, and the group members. | |
Display BACP numbers dialed and the reasons for the calls. | |
Display configured dynamic and static dialer maps and dynamically created BACP temporary static dialer maps. |
To troubleshoot the BACP configuration and operation, use the following debug commands:
| Command | Purpose |
|---|---|
Display BACP errors, protocol actions, and negotiation events and transitions. | |
Display information about events affecting multilink bundles established for BACP. |
This section provides the following BACP configuration examples:
The following example configures an ISDN BRI interface for BACP to make outgoing calls and prevent the peer from negotiating link drops:
interface bri 0 ip unnumbered ethernet 0 dialer load-threshold 10 either dialer map ip 172.21.13.101 name bap-peer 12345668899 encapsulation ppp ppp multilink bap ppp bap call request ppp bap callback accept no ppp bap call accept no ppp bap drop accept ppp bap pending timeout 30 ppp bap number default 5664567 ppp bap number secondary 5664568
In the following example, a dialer rotary group is configured to accept incoming calls:
interface async 1 no ip address encapsulation ppp dialer rotary-group 1 ppp bap number default 5663456 ! ! Set the bandwidth to suit the modem/line speed on the remote side. interface bri 0 no ip address bandwidth 38400 encapsulation ppp dialer rotary-group 1 ppp bap number default 5663457 ! interface bri 1 no ip address encapsulation ppp dialer rotary-group 1 ppp bap number default 5663458 ! interface dialer1 ip unnumbered ethernet 0 encapsulation ppp ppp multilink bap ppp bap call accept ppp bap link types isdn analog dialer load threshold 30 ppp bap timeout pending 60
The following example configures a virtual template interface to use BACP in passive mode:
multilink virtual-template 1 ! interface virtual-template 1 ip unnumbered ethernet 0 encapsulation ppp ppp multilink bap ppp authentication chap callin
interface bri 0 no ip address encapsulation ppp ppp multilink ppp bap number default 4000 ppp bap number secondary 4001
In this example, a dialer rotary group that has four members, each with a different number, accepts incoming dial attempts. The dialer interface does not have a base phone number; the interface which is used to establish the first link in the multilink bundle will provide the appropriate number from its configuration.
interface bri 0 no ip address encapsulation ppp isdn spid1 01234567890 dialer rotary-group 1 no fair-queue no cdp enable ppp bap number default 6666666 ! interface bri 1 no ip address encapsulation ppp isdn spid1 01234567891 dialer rotary-group 1 no fair-queue no cdp enable ppp bap number default 6666667 ! interface bri 2 no ip address encapsulation ppp isdn spid1 01234567892 dialer rotary-group 1 no fair-queue no cdp enable ppp bap number default 6666668 ! interface bri 3 no ip address encapsulation ppp isdn spid1 01234567893 dialer rotary-group 1 no fair-queue no cdp enable ppp bap number default 6666669 ! interface dialer 1 ip unnumbered Ethernet0 encapsulation ppp dialer in-band dialer idle-timeout 300 dialer-group 1 no fair-queue no cdp enable ppp authentication chap ppp multilink bap ppp bap call accept ppp bap callback request ppp bap timeout pending 20 ppp bap timeout response 2 ppp bap max dial-attempts 2 ppp bap monitor load
In this example, a dialer rotary group with two members, each with the same number, accepts incoming dial attempts. The dialer interface has a base phone number because each of its member interfaces is in a hunt group and the same number can be used to access each individual interface.
interface bri 0 no ip address encapsulation ppp isdn spid1 01234567890 dialer rotary-group 1 no fair-queue no cdp enable ! interface bri 1 no ip address encapsulation ppp isdn spid1 01234567890 dialer rotary-group 1 no fair-queue no cdp enable ! interface dialer 1 ip unnumbered Ethernet0 encapsulation ppp dialer in-band dialer idle-timeout 300 dialer-group 1 no fair-queue no cdp enable ppp authentication chap ppp multilink bap ppp bap call accept ppp bap callback request ppp bap timeout pending 20 ppp bap timeout response 2 ppp bap max dial-attempts 2 ppp bap monitor load ppp bap number default 6666666
In the following example, a PRI interface has no BACP number defined and accepts incoming dial attempts (passive mode). The PRI interface has no base phone number defined, so each attempt to add a link would result in a delta of zero being provided to the calling peer. To establish the bundle, the peer should then dial the same number as it originally used.
interface serial 0:23 ip unnumbered Ethernet0 encapsulation ppp dialer in-band dialer idle-timeout 300 dialer-group 1 no fair-queue no cdp enable ppp authentication chap ppp multilink bap ppp bap call accept ppp bap callback request ppp bap timeout pending 20 ppp bap timeout response 2 ppp bap max dial-attempts 2 ppp bap monitor load
In the following example, the BRI interface has no base phone number defined. The number that it uses to establish the bundle is that from the dialer map, and all phone delta operations are applied to that number.
interface bri 0 ip unnumbered Ethernet0 encapsulation ppp dialer in-band dialer idle-timeout 300 dialer map ip 10.1.1.1 name bap_peer speed 56 19998884444 dialer-group 1 no fair-queue no cdp enable ppp authentication chap ppp multilink bap ppp bap call request ppp bap timeout pending 20 ppp bap timeout response 2 ppp bap max dial-attempts 2 ppp bap monitor load
Posted: Mon May 3 11:38:34 PDT 1999
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