Before we move down to MLPPP, it is necessary to understand the meaning of PPP. Point-to-Point Protocol or PPP for short, as described in RFC 1661, would be providing encapsulation protocol for transporting network layer traffic over point-to-point links, like the synchronous serial or (ISDN). Multilink PPP or shortly known as the MLP would be defined in RFC 1990, is considered to be a variant of PPP utilized for aggregating multiple WAN links into one logical channel for the transport of traffic. It would be enabling the load-balancing of traffic from different links and allows some level of redundancy in case of failure in a line on a single link.
The Cisco implementation would be following standards for providing the following functionality: HDLC (High-Level Data Link Control) protocol for encapsulating datagrams; an extensible LCP (Link Control Protocol) for establishing, configuring, and testing the data-link connection; as well as Network Control Protocols (NCPs) for negotiating configuration parameters.
Multilink Point-to-Point Protocol (MLPPP) would be aggregating the multiple PPP physical links into a single virtual connection or logical bundle. More specifically, MLPPP would be bundling multiple link-layer channels into a single network-layer channel. Peers negotiating the MLPPP during the initial phase of the LCP (Link Control Protocol) option negotiation. Each router would be indicating that it is multilink which would be capable by sending the multilink option as part of its LCP configuration request initially.
An MLPPP bundle could be consisting of multiple physical links of the same type like the multiple asynchronous lines or could be consisting of physical links of different types like the leased synchronous lines as well as dial-up asynchronous lines. Packets received with an MLPPP header are considered to be subject to reassembly, fragmentation, and sequencing. Packets received without the MLPPP header couldn’t be sequenced and could be delivered only on a first-come, first-served basis. Before we learn more about the MLPPP, you must acquire the IT Exam dumps offered at the SPOTO Club, if you are aiming to have a bright future in IT Sector.
Traditional MLPPP Application
MLPPP would be utilized for the bundle multiple low-speed links for creating a higher bandwidth pipe such that the combined bandwidth would be available to traffic from all links, as well as supporting LFI (link fragmentation and interleaving) support on the bundle for reducing the transmission delaying of high priority packets. LFI would be interleaving voice packets with fragmented data packets for ensuring timely delivery of voice packets. The below-mentioned figure would be showing how incoming packets are going to be distributed and aggregated into an MLPPP bundle.
MLPPP Aggregation of Traffic Into Single
Because MLPPP would be aggregating multiple link-layer channels onto a single network-layer IP interfacing, protocol layering within the router would be different than for non-multilink PPP.
The below-mentioned figure would be illustrating interface stacking with MLPPP.
Structure of MLPPP
MLPPP LCP Negotiation Option
Multilink PPP would be adding the multilink MRRU (maximum received reconstructed unit) option for LCP negotiation. The MRRU option would be having two functions:
- It would be informing the other end of the linking the maximum reassembled size of the PPP packet payload that the router could receive.
- It would be informing the other end that the router would be supporting MLPPP.
When you would be enabling multilink on your router, the router would be including the MRRU option in LCP negotiation with the default value set to 1500 bytes (user-configurable option) for PPP. If the remote system rejects this option, the local system would be determining that the remote system doesn’t support multilink PPP as well as it would be terminating the link without negotiation.
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