61200510L1-29.1Cber 2006

ConfiguDecem

ration Guide

Multilink PPP

Configuring Multilink PPP for Routers

This Configuration Guide explains the concepts behind configuring your ADTRAN Operating System (AOS) product for multilink PPP support. For detailed information regarding specific command syntax, refer to the AOS Command Reference Guide on your ADTRAN OS System Documentation CD.

This guide consists of the following sections: Understanding Multilink PPP on page 2 Setting up Multilink PPP for Multiple T1 Interfaces on page 3 Verifying the PPP Configuration on page 5 Enhancing Multilink PPP Performance on page 6 Troubleshooting on page 6

Multilink PPP Understanding Multilink PPPUnderstanding Multilink PPP

Multilink PPP is an extension of Point-to-Point Protocol (PPP) that allows multiple physical connections to be combined into one logical connection. This increases the available bandwidth and access speeds for data transfer.

When enabled, the multilink PPP interface is capable of the following: Combining multiple physical links into one logical link Receiving upper layer protocol data units (PDUs) Fragmenting and transmitting packets over the physical links Receiving fragments over the physical links and reassembling them into PDUs

Multilink PPP Internet Access61200510L1-29.1C 2006 ADTRAN, Inc. 2

Multilink PPP Setting up Multilink PPP for Multiple T1 InterfacesSetting up Multilink PPP for Multiple T1 Interfaces

Follow the steps below to set up multilink PPP for multiple T1 interfaces.

Step 1 First, create a time division multiplex (TDM) group. The following example creates a TDM group of 10 DS0s (1 to 24, 1536 Mbps) on the T1 network connection. Use the tdm-group command at the Global Configuration prompt.

(config)#interface t1 1/1(config-t1 1/1)#tdm-group 1 timeslots 1-24(config-t1 1/1)#no shutdown(config-t1 1/1)#exit

Repeat above steps to create a second TDM group for interface T1 1/2.

Step 2To create a PPP interface, use the interface ppp command at the Global Configuration prompt. The following example creates a PPP interface labeled 1. You can use any number for the PPP interface.

(config)#interface ppp 1

Step 3The following command assigns an IP address to the PPP interface using a 24-bit mask. Replace the underlined IP address and subnet mask with the addresses you are using for your application.

(config-ppp 1)#ip address 10.19.2.14 255.255.255.252

Step 4Next, configure the PPP interface for multilink PPP.

(config-ppp 1)#ppp multilink(config-ppp 1)#no shutdown(config-ppp 1)#exit

The following steps assume the Global Configuration mode is currently active. Verify that the prompt of the unit displays (config)#.

The conifuration parameters used in the examples outlined in this document are for instructional purposes only. Please replace all underlined entries (example) with your specific parameters to configure your application. 61200510L1-29.1C 2006 ADTRAN, Inc. 3

Multilink PPP Setting up Multilink PPP for Multiple T1 InterfacesStep 5

Use the cross-connect command at the Global Configuration prompt to create a cross-connect map from a created TDM group on an interface to a virtual interface. All of the cross-connect statements should point to the same PPP interface.

(config)#cross-connect 1 t1 1/1 1 ppp 1

Step 6Repeat steps 1 and 5 for a second T1. When you repeat step 5, you will need to increment the cross-connect number when entering the cross-connect command. For example:

(config)#cross-connect 2 t1 1/2 1 ppp 161200510L1-29.1C 2006 ADTRAN, Inc. 4

Multilink PPP Verifying the PPP ConfigurationVerifying the PPP Configuration

To verify that multilink PPP is configured correctly, use the show interfaces ppp command.

#show interfaces ppp 1ppp 1 is UP Configuration: Keep-alive is set (10 sec.) Queue-type weighted-fair Multilink MTU = 1500, MRRU = 1520 Multilink Fragmentation No authentication IP is configured 10.19.2.14 255.255.255.252 Link thru t1 1/1 is UP; LCP state is OPENED, MTU is 1500 Receive: bytes=3934, pkts=62, errors=0 Transmit: bytes=4817, pkts=126, errors=0 5 minute input rate 144 bits/sec, 0 packets/sec 5 minute output rate 168 bits/sec, 1 packets/sec Link thru t1 1/2 is UP; LCP state is OPENED, MTU is 1500 Receive: bytes=647, pkts=9, errors=0 Transmit: bytes=867, pkts=19, errors=0 5 minute input rate 24 bits/sec, 0 packets/sec 5 minute output rate 24 bits/sec, 0 packets/sec Bundle information Queueing method: weighted fair HDLC tx ring limit: 2 Output queue: 0/1/0/64/0 (size/highest/max total/threshold/drops) Conversations 0/1/256 (active/max active/max total) Available Bandwidth 3072 kilobits/sec IP is UP, IPCP state is OPENED Address=10.19.2.14 Mask=255.255.255.252 Peer address=10.19.2.13 IP MTU=1500, Bandwidth=3072 Kbps61200510L1-29.1C 2006 ADTRAN, Inc. 5

Multilink PPP Enhancing Multilink PPP PerformanceEnhancing Multilink PPP Performance

The fragmentation and interleave options can be used to enhance the multilink operation. The multilink bundle will remain active with a minimum of one physical link. Physical links can be dynamically added or removed from the multilink bundle with minor interruption to traffic flow.

Fragmentation is used to reduce serialization delays of large packets. The fragmentation process evenly divides the data among all links in the bundle with a minimum packet size of 96 bytes. To activate the fragmentation option, enter:

(config-ppp 1)#ppp multilink fragmentation

The interleave process is used with streaming protocols to reduce delay by giving priority to packets identified as high priority. Sequential delivery is guaranteed with multilink fragmentation, but is not guaranteed with multilink interleave operation. To activate the interleave option, enter:

(config-ppp 1)#ppp multilink interleave

Troubleshooting

Use the debug ppp command to activate detailed debug messages about PPP operations. Debug messages are displayed (real time) to the terminal (or Telnet) screen. Use the no form of this command to disable the debug messages. The following options are available:

#debug ppp authentication Activates debug messages pertaining to PPP authentication (CHAP, PAP, EAP, etc.).

#debug ppp errors Activates debug messages that indicate a PPP error was detected (encapsulation error, etc.).

#debug ppp negotiation Activates debug messages associated with PPP negotiation (LCP, IPCP, BCP negotiation, etc.).

#debug ppp verbose Displays all PPP debug messages in real time to the terminal or Telnet screen. 61200510L1-29.1C 2006 ADTRAN, Inc. 6

Multilink PPPUnderstanding Multilink PPPSetting up Multilink PPP for Multiple T1 InterfacesVerifying the PPP ConfigurationEnhancing Multilink PPP PerformanceTroubleshooting

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