Configuration Guide for A7000 dl T1 and E1 WAN Interfaces 2005-12

Configuring PPP Interfaces Understanding SROS Queuing Methods
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Multilink PPP Operation
Multilink PPP operation increases bandwidth on your PPP connection by aggregating multiple
physical links into a single logical bundle. All the physical links in a multilink bundle are treated as a
single entity by the system, allowing each PPP session on the connection to dynamically share the total
bandwidth of the bundle. Single data packets can be fragmented into smaller pieces which may or may
not be transmitted to the network over the same physical link. Multilink PPP devices balance the
transmitted information to evenly use all the physical links in a bundle.
The multilink bundle will remain active with a minimum of one physical link. Physical links can be
dynamically added and removed from the logical bundle with a minor interruption to data flow, so a
failure on one physical link does not halt the overall operation of the bundle. Since all PPP sessions
have access to the entire bundle bandwidth, failure of a single physical connection in the bundle does
not decrease efficiency.
Remote side PPP peers are virtually unaffected by multilink operation; however, they must be aware
that multilink PPP operation is occurring and be able to handle the fragmented frames transmitted on
multiple physical links. Each PPP fragmented frame will include a sequence number to aid in the
reconstruction of PPP frames.
Multilink PPP requires minimal configuration in your SROS product. You must first enable multilink
operation on the PPP interface and then bind the multiple physical interfaces to the single PPP
interface.
The fragmentation and interleave options can be used to enhance multilink operation. Fragmentation is
used to reduce serialization delays during the transmission of large packets. The fragmentation process
evenly divides the data among all the links in the bundle with a minimum packet size of 96 bytes. Use
the ppp multilink fragmentation command (at the Global configuration level) to activate the
fragmentation option for all multilink PPP bundles configured on the system. 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. Use the ppp multilink interleave command (at the Global configuration level) to
activate the interleave option for all multilink PPP bundles configured on the system.
The following commands specify the configuration parameters required for a standard multilink PPP
interface:
ProCurve>enable
ProCurve#config terminal
ProCurve(config)#interface ppp 1
ProCurve(config-ppp 1)#ppp multilink
ProCurve(config-ppp 1)#no shutdown
ProCurve(config-ppp 1)#exit
Now, bind multiple physical interfaces to the same multilink PPP interface:
ProCurve(config)#bind 1 t1 3/1 1 ppp 1
ProCurve(config)#bind 2 t1 3/2 2 ppp 1
ProCurve(config)#bind 3 t1 3/3 3 ppp 1
To create a standard multilink PPP interface using the Web GUI, follow the same procedure for a
standard PPP interface (see Configuring PPP Interfaces on page 12) and click the Multilink
checkbox. Interfaces configured for multilink operation can be bound to more than one physical
interface. To bind a physical interface to an existing multilink interface, specify multilink operation