How to configure ppp on cisco router


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How to configure ppp on cisco router

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How to configure ppp on cisco router

  1. 1. How to Configure PPP on Cisco Router?What is PPP?Point-to-Point connection is one of the most common types of WAN connection. PPPconnections are used to connect LANs to service provider WANs, and to connect LANsegments within an organization network. A LAN-to-WAN point-to-point connectionis also referred to as a serial connection or leased-line connection, because the linesare leased from a carrier (usually a telephone company) and are dedicated for use bythe company leasing the lines.Simply, when you establish a connection to your ISP (Internet Service Provider)through a modem. The connection between the ISP and you make up two points onthe network. Therefore, the protocol that is used for establishing this connectivitybetween the two of you is the Point-to-Point Protocol or the PPP.Note:The default serial encapsulation method when you connect two Cisco routers isHDLC. This means, Cisco HDLC can only work with other Cisco devices. However, whenyou need to connect to a non-Cisco router, you should use PPP encapsulation. This isone of many advantages to using PPP it is not proprietary.PPP can be used over twisted pair, fibre-optic lines, and satellite transmission. PPPprovides transport over ATM, Frame Relay, ISDN and optical links. For security, PPPallows you to authenticate or secure connections using either PasswordAuthentication Protocol (PAP) or the more effective Challenge HandshakeAuthentication Protocol (CHAP).PPP is used to carry out the following functions Data Encapsulations: this is a method used to encapsulate multi-protocol datagrams. Different network-layer protocols are simultaneously transported and encapsulated over the same link, the flexibility of the PPP design enables it to be compatible to most supporting network devices. Link Control Protocol: The LCP is used to establish, configure, and test the data link connection. It’s flexible in handling different sizes of packets, detect a looped-back link, configuration errors, and terminate the link. Network Control Protocol: NCP is used for establishing and configuring different Network layer protocols. PPP enables the simultaneous use of multiple Network layer protocols. Some of the more familiar NCPs are: Internet Protocol Control Protocol AppleTalk Control Protocol Novell IPX Control Protocol Cisco Systems Control Protocol SNA Control Protocol Compression Control Protocol.
  2. 2. How to configure PPP on Cisco Router?You can configure point-to-point encapsulation, software compression, link qualitymonitoring, load balancing across links (multilinks) on R1, R2 and R3 serial interfacebelow.Before you actually configure PPP on a serial interface, we will look at the commandsand the syntax of these commands as shown below. This series of examples showsyou how to configure PPP and some of the options.
  3. 3. 1. How to enable PPP on an InterfaceTo set PPP as the encapsulation method used by a serial or ISDN interface, use theencapsulation ppp interface configuration command.The following example enables PPP encapsulation on serial interface 0/0/0:R1#config tR1(config)#interface se 0/0/0R1(config-if)#encapsulation pppR1(config-if)#endThe encapsulation ppp command has no arguments, however, you must firstconfigure the router with an IP routing protocol (RIP, EIGRP or OSPF) to use PPPencapsulation. You should recall that if you do not configure PPP on a Cisco router,the default encapsulation for serial interfaces is HLDC.2. How to configure CompressionYou can configure point-to-point software compression on serial interfaces after youhave enabled PPP encapsulation. Because this option invokes a softwarecompression process, it can affect system performance. If the traffic already consistsof compressed files (.zip, .tar, or .mpeg, for example), do not use this option.To configure compression over PPP, enter the following commands:R1(config)#interface serial 0/0/0R1(config-if)#encapsulation pppR1(config-if)#compress [predictor | stac]
  4. 4. R1(config-if)#end3. How to configure Link Quality MonitoringOne of the primary functions of LCP when establishing a PPP session includes testingof a link to determine whether the link quality is sufficient to use Layer 3 protocols.The command ppp quality {percentage} ensures that the link meets the qualityrequirement you set; otherwise, the link closes down.How Link Percentage is calculatedThe percentages are calculated for both incoming and outgoing directions. Theoutgoing quality is calculated by comparing the total number of packets and bytessent to the total number of packets and bytes received by the destination node. Theincoming quality is calculated by comparing the total number of packets and bytesreceived to the total number of packets and bytes sent by the destination node.If the link quality percentage is not maintained, the link is deemed to be of poorquality and is taken down. Link Quality Monitoring (LQM) implements a time lag sothat the link does not bounce up and down.Use the configuration commands below to monitor the data traffic on the link andavoids frame looping:R1(config)#interface serial 0/0/0R1(config-if)#encapsulation pppR1(config-if)#ppp quality 80R1(config-if)#endUse the no ppp quality command to disable LQM.4. How to Configure Load Balancing Across Links (MultiLinks)Multilink PPP (also referred to as MP, MPPP, MLP, or Multilink) provides a method forspreading traffic across multiple physical WAN links while providing packetfragmentation and reassembly, proper sequencing, multivendor interoperability, andload balancing on inbound and outbound traffic.MPPP allows packets to be fragmented and sends these fragments simultaneouslyover multiple point-to-point links to the same remote address. The multiple physicallinks come up in response to a user-defined load threshold. MPPP can measure theload on just traffic into the network, or on just traffic going out, but not on thecombined load of both inbound and outbound traffic.Use the following commands to perform load balancing across multiple links:R1#config tR1(config)#interface se0/0/0R1(config-if)#encapsulation pppR1(config-if)#ppp multilink
  5. 5. R1(config-if)#endThe multilink command has no arguments. To disable PPP multilink, use the no pppmultilink command---Original guide from orbit-computer-solutions.comNOTE: What Are the Basic Cisco Router Commands?How to Connect 2 WAN, 1 LAN through a Cisco router