Contents
- Using Multilink PPP over Serial Interface Links
- Finding Feature Information
- Prerequisites for Using Multilink PPP over Serial Interface Links
- Restrictions for Using Multilink PPP over Serial Interface Links
- Information About Using Multilink PPP over Serial Interface Links
- MQC and Multilink PPP over Serial Interface Links
- Multilink Group Interfaces
- How to Configure Multilink PPP over Serial Interface Links
- Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface
- Associating the Serial Interface with the Multilink Group
- Verifying the Multilink PPP over Serial Interface Link Configuration
- Configuration Examples for Using Multilink PPP over Serial Interface Links
- Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface Example
- Associating the Serial Interface with the Multilink Group Example
- Verifying the Multilink PPP over Serial Interface Link Configuration Example
- Where to Go Next
- Additional References
- Feature Information for Using Multilink PPP over Serial Interface Links
Using Multilink PPP over Serial Interface Links
This module contains conceptual information and configuration tasks for using Multilink PPP over serial interface links. Multilink PPP is a method used to reduce latency and jitter for real-time traffic.
- Finding Feature Information
- Prerequisites for Using Multilink PPP over Serial Interface Links
- Restrictions for Using Multilink PPP over Serial Interface Links
- Information About Using Multilink PPP over Serial Interface Links
- How to Configure Multilink PPP over Serial Interface Links
- Configuration Examples for Using Multilink PPP over Serial Interface Links
- Where to Go Next
- Additional References
- Feature Information for Using Multilink PPP over Serial Interface Links
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and 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 module.
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 Using Multilink PPP over Serial Interface Links
Knowledge
Be familiar with the concepts in the "Reducing Latency and Jitter for Real-Time Traffic Using Multilink PPP" module.
Enable Queueing Mechanism
Multilink uses first-in first out (FIFO) queuing for queueing and interleaving packets. Other queueing mechanisms such as low latency queueing (LLQ), weighted fair queueing (WFQ), and class-based weighted fair queueing (CBWFQ) can be used. If you want to use one of these alternative mechanisms, enable it before configuring multilink.
Restrictions for Using Multilink PPP over Serial Interface Links
Number of Links per Multilink Bundle
If a multilink bundle has one link or packet order is not important for interleaved packets, use Link Fragmentation and Interleaving (LFI) without multiclass. Use LFI with multiclass if a multilink bundle has multiple links.
VoIP Support
Only Voice over IP (VoIP) is supported.
Queueing Mechanisms Not Supported
Many of the legacy queueing mechanisms are not supported by multilink. These mechanisms include:
Fair queueing on a virtual template interface
Weighted random early detection (WRED) on a virtual template interface
Custom queueing
Priority queueing
 Note | Fair queueing, WRED, and priority queueing can be configured in a traffic policy using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC). |
Information About Using Multilink PPP over Serial Interface Links
MQC and Multilink PPP over Serial Interface Links
Before using Multilink PPP over serial interface links, a traffic policy (also known as a policy map) must be created. (See the "Prerequisites" section on page 3 .) Policy maps are created using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).
The MQC is a CLI structure that allows users to create traffic polices (policy maps) and attach these policy maps to interfaces. A policy map contains a traffic class and one or more QoS features. A traffic class is used to classify traffic. The QoS features in the traffic policy determine how to treat the classified traffic.
Multilink Group Interfaces
A multilink group interface is a collection of interfaces bundled together in the multilink PPP configuration. With a multilink group interface, you can bundle interfaces into logical multilink groups.
How to Configure Multilink PPP over Serial Interface Links
- Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface
- Associating the Serial Interface with the Multilink Group
- Verifying the Multilink PPP over Serial Interface Link Configuration
Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface
Before proceeding with this task, you must create a policy map. The policy map contains the configuration parameters used to apply the specific quality of service feature to the network traffic. To create a policy map, use the MQC.
1.
enable
2.
configure
terminal
3.
interface
multilink
multilink-bundle-number
4.
ip
address
ip-address
mask
[secondary]
5.
service-policy
output
policy-map-name
6.
service-policy
input
policy-map-name
7.
ppp
multilink
fragment
delay
milliseconds
[microseconds]
8.
ppp
multilink
interleave
9.
ppp
multilink
multiclass
10.
end
DETAILED STEPS
Associating the Serial Interface with the Multilink Group
1.
enable
2.
configure
terminal
3.
interface
serial
slot
/
port
:
timeslot
4.
no
fair-queue
5.
encapsulation
ppp
6.
ppp
multilink
7.
ppp
multilink
group
group-number
8.
end
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable
Example: Router> enable |
Enables privileged EXEC mode.
|
| Step 2 |
configure
terminal
Example: Router# configure terminal |
Enters global configuration mode. |
| Step 3 |
interface
serial
slot
/
port
:
timeslot
Example: Router# interface serial 4/1:23 Example: |
Specifies a serial interface created on a channelized E1 or channelized T1 controller (for ISDN PRI, channel-associated signaling, or robbed-bit signaling), and enters interface configuration mode.
|
| Step 4 |
no
fair-queue
Example: Router(config-if)# no fair-queue |
Disables WFQ (or DWFQ for VIP-enabled routers). |
| Step 5 |
encapsulation
ppp
Example: Router(config-if)# encapsulation ppp |
Sets the serial interface encapsulation method used by the interface. |
| Step 6 |
ppp
multilink
Example: Router(config-if)# ppp multilink |
Enables Multilink on an interface. |
| Step 7 |
ppp
multilink
group
group-number
Example: Router(config-if)# ppp multilink group 1 |
Restricts a physical link to joining only a designated multilink group interface.
|
| Step 8 |
end
Example: Router(config-if)# end |
(Optional) Exits interface configuration mode. |
Verifying the Multilink PPP over Serial Interface Link Configuration
1.
enable
2.
show
interfaces
[type number] [first] [last] [accounting]
3.
show
ppp
multilink
[active | inactive | interface bundle-interface | [username name] [endpoint endpoint]]
4.
show
policy-map
interface
interface-name
[vc [vpi/] vci] [dlci dlci] [input | output]
5.
exit
DETAILED STEPS
| Command or Action | Purpose | |
|---|---|---|
| Step 1 |
enable
Example: Router> enable |
Enables privileged EXEC mode.
|
| Step 2 |
show
interfaces
[type number] [first] [last] [accounting] Example: Router# show interfaces |
(Optional) Displays statistics for all interfaces configured on the router or access server. |
| Step 3 |
show
ppp
multilink
[active | inactive | interface bundle-interface | [username name] [endpoint endpoint]] Example: Router# show ppp multilink |
(Optional) Displays bundle information for mutlilink bundles. |
| Step 4 |
show
policy-map
interface
interface-name
[vc [vpi/] vci] [dlci dlci] [input | output] Example: Router# show policy-map interface serial0/0 |
(Optional) Displays the packet statistics of all classes that are configured for all service policies either on the specified interface or subinterface or on a specific permanent virtual circuit (PVC) on the interface. |
| Step 5 |
exit
Example: Router# exit |
(Optional) Exits privileged EXEC mode. |
Configuration Examples for Using Multilink PPP over Serial Interface Links
- Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface Example
- Associating the Serial Interface with the Multilink Group Example
- Verifying the Multilink PPP over Serial Interface Link Configuration Example
Configuring Multilink PPP over Serial Interface Links on a Multilink Group Interface Example
The following is an example of configuring Multilink PPP over serial interface links on a multilink group interface:
Router> enable
Router# configure terminal
Router(config)# interface multilink 1
Router(config-if)# ip address 10.10.100.1 255.255.255.0
Router(config-if)# service-policy output policy1
Router(config-if)# service-policy input policy1
Router(config-if)# ppp multilink fragment delay 20
Router(config-if)# ppp multilink interleave
Router(config-if)# ppp multilink multiclass
Router(config-if)# end
Associating the Serial Interface with the Multilink Group Example
The following is an example of associating the serial interface serial4/1 with the multilink group:
Router> enable
Router# configure terminal
Router(config)# interface serial 4/1:23
Router(config-if)# no fair-queue
Router(config-if)# encapsulation ppp
Router(config-if)# ppp multilink
Router(config-if)# ppp multilink group 1
Router(config-if)# end
Verifying the Multilink PPP over Serial Interface Link Configuration Example
You can verify the Multilink PPP over serial interface links configuration by using one or more of the following show commands:
show interfaces
show ppp multilink
show policy-map interface
The following section provides sample output of the show ppp multilink command only. For sample output of the other commands, see the appropriate Cisco IOS Release 12.3 T command reference publication.
show ppp multilink Command Output Example
The following is an example of the show ppp multilink command output. In this example, one multilink bundle called 7206-2 is on the system. This bundle has two member links: one active link and one inactive link.
Router# show ppp multilink
Multilink2, bundle name is 7206-2
Endpoint discriminator is 7206-2
Bundle up for 00:00:09, 1/255 load
Receive buffer limit 12000 bytes, frag timeout 1500 ms
0/0 fragments/bytes in reassembly list
0 lost fragments, 0 reordered
0/0 discarded fragments/bytes, 0 lost received
0x0 received sequence, 0x3 sent sequence
Member links:1 active, 1 inactive (max not set, min not set)
Se3/2, since 00:00:10, 240 weight, 232 frag size
Se3/3 (inactive)
Where to Go Next
To use Multilink PPP over ATM links, see the "Using Multilink PPP over ATM Links" module.
To use Multilink PPP over Frame Relay, see the "Using Multilink PPP over Frame Relay" module.
To use Multilink PPP over dialer interface links, see the "Using Multilink PPP over Dialer Interface Links" module.
Additional References
The following sections provide references related to Multilink PPP over serial interface links:
Related Documents
|
Related Topic |
Document Title |
|---|---|
|
QoS commands: complete command syntax, command modes, command history, defaults, usage guidelines, and examples |
Cisco IOS Quality of Service Solutions Command Reference |
|
LLQ, WFQ, CBWFQ, PQ, CQ, FIFO and other queueing mechanisms |
"Configuring Weighted Fair Queueing" module |
|
MQC |
"Applying QoS Features Using the MQC" module |
|
Multilink PPP configurations |
"Configuring Media-Independent PPP and Multilink PPP" module |
|
Multilink PPP overview module |
"Reducing Latency and Jitter for Real-Time Traffic Using Multilink PPP" module |
|
Multilink PPP over ATM links (including ATM interfaces and ATM PVCs) |
"Using Multilink PPP over ATM Links" module |
|
Multilink PPP over Frame Relay |
"Using Multilink PPP over Frame Relay" module |
|
Multilink PPP over dialer interface links |
"Using Multilink PPP over Dialer Interface Links" module |
Standards
|
Standard |
Title |
|---|---|
|
No new or modified standards are supported, and support for existing standards has not been modified. |
-- |
MIBs
|
MIB |
MIBs Link |
|---|---|
|
No new or modified MIBs are supported, and support for existing MIBs has not been modified. |
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
|
RFC |
Title |
|---|---|
|
RFC 1990 |
The PPP Multilink Protocol (MP) |
|
RFC 2686 |
Multiclass Extension to Multilink PPP (MCML) |
Technical Assistance
|
Description |
Link |
|---|---|
|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for Using Multilink PPP over Serial Interface Links
The following table provides release information about the feature or features described in this module. This table 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.
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.
|
Feature Name |
Software Releases |
Feature Configuration Information |
|---|---|---|
|
Distributed Link Fragmentation and Interleaving Over Leased Lines |
12.2(8)T |
The Distributed Link Fragmentation and Interleaving over Leased Lines feature extends distributed link fragmentation and interleaving functionality to leased lines. This feature was extensively rewritten from the perspective of using Multilink PPP for link fragmentation and interleaving over serial interface links. |
|
Distributed Link Fragmentation and Interleaving for Frame Relay and ATM Interfaces on Cisco 7500 Series Routers |
12.2(4)T |
The Distributed Link Fragmentation and Interleaving (dLFI) for Frame Relay and ATM Interfaces on Cisco 7500 Series Routers feature extends link fragmentation and interleaving functionality to VIP-enabled Cisco 7500 series routers. This feature was extensively rewritten from the perspective of using Multilink PPP for link fragmentation and interleaving over serial interface links. |