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WAN technologies

What is: IP unnumbered?

IP unnumbered is method that you can use to enable IP processing on a Point to Point interface without assigning an it an IP address to conserve the IP address space. All you need to do, is to select an interface that you are going to borrow its IP address; preferrably the loopback interface because it is always in the up state ,then use the command IP unnumbered <selected-interface> under the point to point interface. To summarize: This feature helps in conserving IPv4 addresses. Mostly used in dial-up or DSL setups. The IP unnumbered command must be used under a …

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How-to:Configure PPP authentication Part2 (CHAP)

The second and the most secure authentication method in PPP is CHAP. CHAP stands for challenge Handshake Authentication Protocol. How CHAP works? If CHAP is negotiated successfully during the LCP phase, the authenticator sends a challenge message to the peer. The peer responds to the challenge with a value calculated through an MD5 function. The authenticator then verifies the received value against its own calculated value. If they match the authentication is successful. In our example R1 is the authenticator and R2 is the authenticated peer. R1 will send a challenge to R2; R2 will calculate a response to the …

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How-to: Configure PPP authentication Part1 (PAP)

PPP has two different authentication methods, in today’s post we are going to explore the first method which is PAP. PAP stands for Password Authentication Protocol which is a simple authentication method. PAP is considered an insecure method because the password is sent in clear text format over the PPP link and has no protection to replay and brute force attacks. How PAP works? During the LCP phase both ends can negotiate the use of specific authentication protocol; if it was successful and LCP is completed a series of authentication messages are exchanged to identify the remote end. In our …

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PPP in brief

The Point-to-Point Protocol (PPP) provides a standard method for transporting multi-protocol packets over point-to-point links between two peers. In order to establish a communication link between two peers, each end of the PPP link must first send LCP packets to configure and test the data link. After the link has been established, the peer may be authenticated (optional). Then, PPP must send NCP packets to choose and configure one or more network-layer protocols. Once each of the chosen network-layer protocols has been configured, datagrams from each network-layer protocol can be sent over the link. The link will remain configured for …

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How-to: Configure Frame-relay Switching

Routers can be configured as Frame Relay switches to be used mostly in service provider or LAB environments. Lets see how you can configure frame-relay switch to use your in studies. On a Frame Relay switch, frames from a Frame Relay PVC arriving o­n an incoming interface are switched to a Frame Relay PVC o­n an outgoing interface. The switching paths taken by the frames are based o­n the static Frame Relay route table. In the following example two routers (Router1 & Router2) are connected via a router acting as a dedicated frame-relay switch (FRSW) . Configuration steps: Enable frame …

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How to Configure Frame-relay interfaces

Frame relay interfaces can be configured as Physical, Multipoint and point-to-point interfaces. Frame relay routing protocols and mostly all network configuration is heavily affected by interface type selected. In the following digram R1 is connected to R2 using frame-relay and we are going to explore different configuration options. Task1: Configure frame-relay PVC between R1 and R2 using physical Physical interfaces are considered to be multipoint interfaces by default, which means that address resolution is essential in order for both ends to communicate. Address resolution can be accomplished manually using the frame-relay map command or dynamically using inverse ARP. Dynamic address …

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