User`s guide

108 XSR User’s Guide
PPP Features Chapter 6
Configuring PPP
 The XSR can receive upper layer protocol data units (PDU)
fragmented using the multilink header and reassemble the fragments
into the original PDU for processing
 The XSR can receive PDUs of size N octets where N is specified as
part of the option even if N is larger than the maximum receive unit
(MRU) for a single physical link
When a packet is transmitted over a multilink bundle it is encapsulated by a
multilink header, which includes information to allow the packets sent over
the links in the bundle to be sequenced.
Functionality provided by MLPPP on the XSR includes:
 Learned number of fragments to be sent on each link and the bundle
 Fragmentation/reassembly
 Detection of fragment loss
 Optimal buffer usage
 MTU size determination
 Management of MLPPP bundles
 MIB support for network management
 Up to four T1/E1 lines can be aggregated running MLPPP
IP Control Protocol (IPCP)
IPCP negotiates the following options, as referenced in RFC-1332:
 The IP address of the system
 The compression protocol to be applied on IP datagrams (Van
Jacobson Compressed TCP/IP)
Along with the above support, the following IPCP extension is also offered:
 Primary and Secondary DNS and NBNS address
Once negotiation is successful, IPCP allows IP traffic over the established PPP
link. The negotiated IP addresses and MTU of the interface are passed on to
the higher layer (IP) to update its tables.