Verify the MMP Configuration
Configuring Multichassis Multilink PPP
This chapter describes the use of Multichassis Multilink PPP (MMP) on the Cisco AccessPath-TS3 Model 531 Integrated Access System. The chapter begins with the principles of MMP and how it works, and then describes procedures for configuring MMP.
To enable MMP on the AccessPath-TS3 system, you must configure the Access Servers.
Topics in this section include the following:
Understanding MMP
This section presents a brief overview of MMP operations and includes the following topics:
MMP is a feature in Cisco IOS Release 11.2 and later that extends Multilink Point-to-Point Protocol (PPP) (MP, also known as MLP) functionality across multiple chassis.
MP gives users additional bandwidth on demand by splitting and recombining packets across a logical pipe (bundle) formed by multiple links. On the transmit end, MP provides for the fragmentation of a single packet into multiple packets for transmission across multiple PPP links. On the receive end, MP provides packet reassembly from multiple PPP links.
MMP enhances MP by permitting MP links from a single client to terminate on different access servers. The whole process is invisible to the user.
MMP allows Internet service providers (ISPs) and enterprise system administrators the flexibility to group multiple access servers into a single rotary group that users can access from a single number. The MMP client is unaware that the MP bundle is made up of links terminating on different access servers.
Why Use MMP?
MMP is particularly suited to the AccessPath-TS3 system for the following reasons:
- Scalability—You can add Access Servers to the AccessPath-TS3 system.
- Dial-up pooling—MMP permits the AccessPath-TS3 system to use Access Servers for the dial-up pool and to reassemble and resequence MP packets.
- Stack grouping—All Access Servers can be designated as a stack group. The stack group can support a variety of technologies.
- Single access number—Any stack group member can answer a call coming into a single access number. This single access number would normally be applied via a telco hunt group (a single number the telco applies to a group of physical connections). The central office switch can assign any call made to the access number to any ISDN B channel on any Primary Rate Interface (PRI) within this hunt group.
How MMP Works
MMP works with the Stack Group Bidding Protocol (SGBP), which supports bidding and arbitration across multiple components in the AccessPath-TS3 system.
Figure 8-1 MMP Operation
In Figure 8-1, User X (connected to Router Y) takes advantage of the added bandwidth provided by MP when dialing into the AccessPath-TS3 system stack. The Access Server that answers the first call will host the master bundle for MMP calls. The following sequence illustrates a typical scenario when the AccessPath-TS3 system is configured in a peer stack group:
1. Call 1 is made and Access Server A asks other components whether anyone has received the first call from Router Y.
2. If no one received the first call from Router Y, Access Server A will accept the call.
3. When User X needs more bandwidth, Call 2 is made and, in this example, Access Server C accepts the call and informs the stack group.
4. The stack group members bid for ownership of the call, but Access Server A wins the bid because it already has an MP session with User X.
5. Access Server A sets up an L2F tunnel to pass raw PPP data between the Access Server C and itself.
Configuring MMP on the Access Servers
The Access Servers in the AccessPath-TS3 system use MMP by default, for multichannel operation. SGBP is used to control channel termination.
Configure
Table 8-1 Configuring MMP—Access Server
| Step
|
Command
|
Purpose
|
| 1
|
AS01> enable
Password: <password>
AS01#
|
Enter enable mode.
Enter the password.
You have entered enable mode when the prompt changes to AS01#.
|
| 2
|
AS01# config term
Enter configuration commands, one per line. End with CNTL/Z.
AS01(config)#
|
Enter global configuration mode. You have entered global configuration mode when the prompt changes to AS01(config)#.
|
| 3
|
AS01(config)# sgbp group mystack
|
Create a stack group and assign this Access Server to it.
Substitute your stack group name for mystack.
|
| 4
|
AS01(config)# sgbp member AS02 172.16.1.34
AS01(config)# sgbp member AS03 172.16.1.35
AS01(config)# sgbp member AS04 172.16.1.36
AS01(config)# sgbp member AS05 172.16.1.37
AS01(config)# sgbp member AS06 172.16.1.38
AS01(config)# sgbp member AS07 172.16.1.39
AS01(config)# sgbp member AS08 172.16.1.40
AS01(config)# sgbp member AS09 172.16.1.41
AS01(config)# sgbp member AS10 172.16.1.42
AS01(config)# sgbp member AS11 172.16.1.43
AS01(config)# sgbp member AS12 172.16.1.44
AS01(config)# sgbp member AS13 172.16.1.45
AS01(config)# sgbp member AS14 172.16.1.46
AS01(config)# sgbp member AS15 172.16.1.47
AS01(config)# sgbp member AS16 172.16.1.48
AS01(config)# sgbp member AS17 172.16.1.49
AS01(config)# sgbp member AS18 172.16.1.50
AS01(config)# sgbp member AS19 172.16.1.51
AS01(config)# sgbp member AS20 172.16.1.52
AS01(config)# sgbp member AS21 172.16.1.53
|
Specify the host name and IP address of the peer member of the stack group. In this example, there are 21 peers.
|
| 5
|
AS01(config)# sgbp seed-bid default
|
Set the bidding level for a stack group member. Default indicates that the Access Server will only bid for an external call if it is already bundling the first channel of the same set.
|
| 6
|
AS01(config)# sgbp source-ip 172.16.1.33
|
Set the source IP address for SGBP packets. The AccessPath-TS3 system uses Loopback 0 addresses for SGBP source IP addresses.
|
| 7
|
AS01(config)# username mystack password mypassword
|
Assign a password for the SGBP peers to exchange. The username must match the stack group name. The same password must be configured in each Access Server in the SGBP group. Substitute your stack group name for mystack, and your SGBP password for mypassword.
|
| 8
|
AS01(config)# end
AS01#
%SYS-5-CONFIG_I: Configured from console by console
|
Return to privileged EXEC mode.
This message is normal and does not indicate an error.
|
MMP
Verify the MMP Configuration
To verify the MMP configuration on each Access Server :
- Enter the show sgbp command:
Group Name: test Ref: 0x4780B252
Seed bid: default, 50, default seed bid setting
Member Name: AS02 State: active Id: 9
Group Name: test Ref: 0x4780B54D
Seed bid: default, 50, default seed bid setting
Member Name: AS01 State: active Id: 1
Note the following:
- Check to make sure State is active. State set to idle indicates there is a misconfiguration on either side.
- Check to make sure the username and password are configured for the SGBP group; otherwise the Access Servers will not be able to talk to each other.
If you are having trouble:
- Enter the debug sgbp ? command to view a list of available debugging commands:
hellos SGBP connection hellos
queries SGBP mastership queries
- Enter the debug sgbp errors command to view error messages. When you finish viewing the messages, enter the no debug sgbp errors command to turn off the messages.
*Mar 4 11:55:24.105 EST: %SGBP-1-MISSCONF: Possible misconfigured member
*Mar 4 11:55:41.185 EST: %SGBP-7-NORESP: Fail to response to mystack group
test, may not have password
Error messages are displayed if one Access Server (AS11) shows an SGBP group configured, but the group is not configured for another Access Server in the group. Error messages are also displayed if the password is not configured for the SGBP group.
- Enter the debug sgbp events command to view event messages. When you finish viewing the messages, enter the no debug sgbp events command to turn off the messages.
*Mar 4 12:26:46.441 EST: %SGBP-7-CLOSE: Closing pipe for member AS02
*Mar 4 12:26:46.445 EST: %SGBP-5-LEAVING: Member AS02 leaving mystack
The above event message indicates that the SGBP connection went down, and that AS02 is no longer part of the SGBP group mystack. You can check AS02 for the reasons why the SGBP connection went down. Possibly, the SGBP member entry for AS01 was removed, or there is no communication between AS01 and AS02.
Posted: Mon Jan 20 21:56:21 PST 2003
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