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Contents
Multilink PPP is a method used to reduce latency and jitter for real-time traffic. This module contains conceptual information and configuration tasks for using Multilink PPP over Frame Relay.
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.
Be familiar with the concepts in the "Reducing Latency and Jitter for Real-Time Traffic Using Multilink PPP" module.
Multilink uses first-in first out (FIFO) queuing for queuing and interleaving packets. Other queuing mechanisms such as low latency queuing (LLQ), weighted fair queuing (WFQ), and class-based weighted fair queuing (CBWFQ) can be used. If you want to use one of these alternative mechanisms, enable it before configuring Multilink.
Frame Relay Traffic Shaping (FRTS) must be enabled on the Frame Relay interface.
Only one link per multilink bundle is supported.
Only Voice over IP (VoIP) is supported; Voice over Frame Relay (VoFR) is not supported.
Only one PVC is supported per virtual template.
To handle congestion, a shape policy in an MLP over Frame Relay should be configured via a map class and attached to the PVC.
Before using Multilink PPP over Frame Relay, FRTS must be enabled.
Note | On the Cisco 7200 and lower series of routers, the frame-relay traffic-shaping command is used to enable FRTS. On the Cisco 7500 and higher series of routers, the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC) is used to enable FRTS. For more information about MQC, see the "MQC and Multilink PPP over Frame Relay" section. |
FRTS is a Cisco traffic shaping mechanism. A traffic shaping mechanism allows you to regulate (that is, "shape") the packet flow on a network. When you shape traffic, you control the speed of traffic leaving an interface. This way, you can match the flow of the traffic to the speed of the interface and avoid bottlenecks on the network.
Cisco has long provided support for forward explicit congestion notification (FECN) for DECnet and OSI, and backward explicit congestion notification (BECN) for Systems Network Architecture (SNA) traffic using Logical Link Control, type 2 (LLC2) encapsulation via RFC 1490 and discard eligible (DE) bit support. FRTS builds upon this existing Frame Relay support with additional capabilities that improve the scalability and performance of a Frame Relay network, increasing the density of virtual circuits (VCs) and improving response time.
FRTS can eliminate bottlenecks in Frame Relay networks that have high-speed connections at the central site and low-speed connections at branch sites. You can configure rate enforcement--a peak rate configured to limit outbound traffic--to limit the rate at which data is sent on the VC at the central site.
Before using Multilink PPP over Frame Relay, a policy map must be created. (See the "Prerequisites" section.) Policy maps are created using the Modular Quality of Service (QoS) Command-Line Interface (CLI) (MQC).
A virtual template interface is logical interface configured with generic configuration information for a specific purpose or configuration common to specific users, plus router-dependent information. The template takes the form of a list of Cisco IOS interface commands that are applied to virtual access interfaces, as needed.
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.
While the first two procedures are listed as optional, you must choose one or the other according to the Cisco router that you are using in your network.
These steps apply if you are using the Cisco 7500 series router or the Cisco 7600 series router only. If you are using another series of Cisco router, do not complete these steps. Instead, advance to Configuring Multilink PPP over Frame Relay 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 a specific QoS features such as distributed LLQ (dLLQ) to the network traffic. To create a policy map and configure the appropriate QoS feature, use the MQC. See the MQC and Multilink PPP over Frame Relay.
1.
enable
2.
configure
terminal
3.
interface
virtual-template
number
4.
bandwidth
kbps
5.
ip
address
ip-address
mask
[secondary]
6.
service-policy
output
policy-map-name
7.
service-policy
input
policy-map-name
8.
ppp
multilink
9.
ppp
multilink
fragment
delay
milliseconds
[microseconds]
10.
ppp
multilink
interleave
11.
end
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
virtual-template
number
Example: Router(config)# interface virtual-template 1 |
Creates a virtual template and enters interface configuration mode. | ||
Step 4 |
bandwidth
kbps
Example: Router(config-if)# bandwidth 32 |
Sets the bandwidth value for an interface.
| ||
Step 5 |
ip
address
ip-address
mask
[secondary]
Example: Router(config-if)# ip address 10.10.100.1 255.255.255.0 |
Sets a primary IP address for an interface. This command can also set the optional secondary IP address for an interface. | ||
Step 6 |
service-policy
output
policy-map-name
Example: Router(config-if)# service-policy output policy1 |
Attaches the previously created QoS traffic policy (policy map). See the "Prerequisites" section on page 4 . The policy map evaluates and applies QoS features for traffic leaving the interface. | ||
Step 7 |
service-policy
input
policy-map-name
Example: Router(config-if)# service-policy input policy1 |
Attaches the previously created QoS traffic policy (policy map). See the "Prerequisites" section on page 4 . The policy map evaluates and applies QoS features for traffic entering the interface. | ||
Step 8 |
ppp
multilink
Example: Router(config-if)# ppp multilink |
Enables MLP on the interface. | ||
Step 9 |
ppp
multilink
fragment
delay
milliseconds
[microseconds]
Example: Router(config-if)# ppp multilink fragment delay 20 |
Specifies a maximum size in units of time for packet fragments on a Multilink PPP (MLP) bundle.
| ||
Step 10 |
ppp
multilink
interleave
Example: Router(config-if)# ppp multilink interleave |
Enables interleaving of packets among the fragments of larger packets on a multilink bundle. | ||
Step 11 |
end
Example: Router(config-if)# end |
(Optional) Exits interface configuration mode. |
If you are using the Cisco 7500 series router or the Cisco 7600 series router, do not complete these steps. Instead, complete the steps in Configuring Multilink PPP over Frame Relay on a Virtual Template Interface.
Before proceeding with this task, you must create a policy map. The policy map contains the configuration parameters used to apply a specific QoS features such as distributed LLQ (dLLQ) to the network traffic. To create a policy map and configure the appropriate QoS feature, use the MQC. See the MQC and Multilink PPP over Frame Relay.
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.
end
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
multilink
multilink-bundle-number
Example: Router(config)# interface multilink 1 |
Creates a multilink bundle and enters interface configuration mode. |
Step 4 |
ip
address
ip-address
mask
[secondary]
Example: Router(config-if)# ip address 10.10.100.1 255.255.255.0 |
Sets a primary IP address for an interface. This command can also set the optional secondary IP address for an interface. |
Step 5 |
service-policy
output
policy-map-name
Example: Router(config-if)# service-policy output policy1 |
Attaches the previously created QoS traffic policy (policy map). See the "Prerequisites" section on page 6 . The policy map evaluates and applies QoS features for traffic leaving the interface. |
Step 6 |
service-policy
input
policy-map-name
Example: Router(config-if)# service-policy input policy1 |
Attaches the previously created QoS traffic policy (policy map). See the "Prerequisites" section on page 6 . The policy map evaluates and applies QoS features for traffic entering the interface. |
Step 7 |
ppp
multilink
fragment
delay
milliseconds
[microseconds]
Example: Router(config-if)# ppp multilink fragment delay 20 |
Specifies a maximum size in units of time for packet fragments on a multilink bundle. |
Step 8 |
ppp
multilink
interleave
Example: Router(config-if)# ppp multilink interleave |
Enables interleaving of packets among the fragments of larger packets on a multilink bundle. |
Step 9 |
end
Example: Router(config-if)# end |
(Optional) Exits interface configuration mode. |
After configuring Multilink PPP over Frame Relay on a multilink group interface, the next step is to associate the virtual template interface with the multilink group by completing the steps in the following section.
If you are using a Cisco 7500 series router or a Cisco 7600 series router, advance to Associating the Virtual Template Interface with a Frame Relay PVC to continue.
1.
enable
2.
configure
terminal
3.
interface
virtual-template
number
4.
no
ip
address
5.
ppp
multilink
group
group-number
6.
end
1.
enable
2.
configure
terminal
3.
interface
type
number
[name-tag]
4.
frame-relay
traffic-shaping
5.
frame-relay
interface-dlci
dlci
[ietf | cisco] [voice-cir cir] [ppp virtual-template-name]
6.
class
name
7.
end
1.
enable
2.
show
frame-relay
pvc
[interface
interface] [dlci] [64-bit]
3.
show
interfaces
[type
number] [first] [last] [accounting]
4.
show
ppp
multilink
[active |
inactive |
interface
bundle-interface | [username
name] [endpoint
endpoint]]
5.
show
policy-map
interface
interface-name
[vc [vpi/]
vci] [dlci
dlci] [input |
output]
6.
exit
Command or Action | Purpose | |
---|---|---|
Step 1 |
enable
Example: Router> enable |
Enables privileged EXEC mode. |
Step 2 |
show
frame-relay
pvc
[interface
interface] [dlci] [64-bit]
Example: Router# show frame-relay pvc |
(Optional) Displays statistics about permanent virtual circuits (PVCs) for Frame Relay interfaces. |
Step 3 |
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 4 |
show
ppp
multilink
[active |
inactive |
interface
bundle-interface | [username
name] [endpoint
endpoint]]
Example: Router# show ppp multilink |
(Optional) Displays bundle information for multilink bundles. |
Step 5 |
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 PVC on the interface. |
Step 6 |
exit
Example: Router# exit |
(Optional) Exits privileged EXEC mode. |
The following is an example of configuring Multilink PPP over Frame Relay on a virtual template interface:
Router> enable
Router# configure terminal
Router(config)# interface virtual-template 1
Router(config-if)# bandwidth 32
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
Router(config-if)# ppp multilink fragment delay 20
Router(config-if)# ppp multilink interleave
Router(config-if)# end
The following is an example of configuring Multilink PPP over Frame Relay 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)# end
The following is an example of associating the virtual template interface with the multilink group:
Router> enable
Router# configure terminal
Router(config)# interface virtual-template 1
Router(config-if)# no ip address
Router(config-if)# ppp multilink group 1
Router(config-if)# end
The following is an example of associating the virtual template interface with a Frame Relay PVC:
Router> enable
Router# configure terminal
Router(config)# interface serial1/0/0/1:0
Router(config-if)# frame-relay interface-dlci 100 ppp virtual-template1
Router(config-fr-dlci)# class frdlci
Router(config-fr-dlci)# end
You can verify the Multilink with PPP over Frame Relay configuration by using one or more of the following show commands:
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 12.3T command reference publication.
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 Multilink1, bundle name is 7206-2 Endpoint discriminator is 7206-2 Bundle up for 00:00:15, 1/255 load Receive buffer limit 12000 bytes, frag timeout 3428 ms 0/0 fragments/bytes in reassembly list 1 lost fragments, 1 reordered 0/0 discarded fragments/bytes, 0 lost received 0x3 received sequence, 0x3 sent sequence Member links:1 active, 1 inactive (max not set, min not set) Vi2, since 00:00:15, 105 weight, 93 frag size Vt1 (inactive)
To use Multilink PPP over ATM links, see the "Using Multilink PPP over ATM Links" module.
To use Multilink PPP over dialer interface links, see the "Using Multilink PPP over Dialer Interface Links" module.
To use Multilink PPP over serial interface links, see the "Using Multilink PPP over Serial Interface Links" module.
The following sections provide references related to using Multilink PPP over Frame Relay.
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 |
FRTS |
"MQC-Based Frame Relay Traffic Shaping" module |
Multilink PPP configurations |
"Configuring Media-Independent PPP and Multilink PPP" module |
Virtual template interfaces |
"Configuring Virtual Template Interfaces" 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 dialer interface links |
"Using Multilink PPP over Dialer Interface Links" module |
Multilink PPP over serial interface links |
"Using Multilink PPP over Serial Interface Links" module |
Standard |
Title |
---|---|
No new or modified standards are supported, and support for existing standards has not been modified. |
-- |
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: |
RFC |
Title |
---|---|
RFC 1990 |
The PPP Multilink Protocol (MP) |
RFC 2686 |
Multiclass Extension to Multilink PPP (MCML) |
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. |
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 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 Frame Relay. |
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 Frame Relay. |