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February 2012

Backup Interfaces

In Theory A backup interface is an interface that stays inactive as long as the primary interface is in “up/up” state, but becomes active when the primary interface’s protocol status becomes “down”. When the protocol on the primary interface comes back up, the backup interface moves back in a “standby …

ODR

1. What is ODR? ODR(On Demand Routing) is a routing protocol that runs on top of CDP and that is best suited for a hub and spoke topology. If the CDP traffic is already active between the routers on a Hub and Spoke network, the use of ODR makes sense …

Frame Relay Switching

1. Frame Relay Switching When setting up a Frame Relay DCE device, we need to follow the following steps. 1. Enable Frame Relay Switching 2. Change The interface type 3. Glue the DLCIs together 1.1 Enable Frame Relay Switching The command is ultra simple, but without it the device will …

PPPoE – PPP over Ethernet

PPP can be encapsulated over Ethernet and it can be used to offer authentication over Ethernet connections. It cannot be used for Multilinking Ethernet connections. When using PPPoE we need a server and a client. 1. Server Side Configuring the server makes use of the Virtual Template/Virtual Access interfaces. We …

PPPoFR – PPP over Frame Relay

1. PPPoFR PPP can be used encapsulated in Frame Relay to offer all PPP features over an existing Frame Relay network. The first feature that comes to mind is probably authentication, but PPPoFR can also be used to offer advantages such as Multilink PPP over Frame Relay or PPP compression. …

PPP Multilink

1. PPP Mulitlink One feature that PPP can offer is the posibility to bundle multiple physical links into one logical link, much like an EtherChannel interface available on the Ethernet Switches. Considering two routers connected back-to-back over more than one serial links. Each serial interface can be configured for PPP …

Multilink Frame Relay

Frame Relay can be used to group multiple physical interfaces in one logical interface, much like an EtherChannel interface available on the Ethernet Switches. It offers load-balancing and higher availability since the link will be up as long as one physical connection is up. In order to do this, bothe …

PPP 101

PPP is an open-standard, media-independent Layer 2 protocol that can provide such features as authentication, multilink, compression, reliability. PPP uses 2 negotiation phases. First, LCP (Link Control Protocol) is used to set up the link and to negotiate authentication, compression mechanisms, available MTU size, and so on, and then there’s …

PPP Authentication – CHAP

1. CHAP algorithm CHAP is more secure than PAP because even though it sends usernames in clear text, it uses an MD5 hash instead of a clear text password for authentication. When a router is set to ask for authentication, it will send a CHAP Challenge to the other router …

PPP Authentication – PAP

PAP is a simple but not very secure authentication protocol. It sends the username and password information in clear text. 1. One-way authentication On the router that asks for authentication: On the router that is authenticating: This is clearly a one-way authentication. Only R2 authenticates to R1. 2. Two-way authentication …