An introduction to Point-to-Point Protocol

The big picture PPP is a layer 2 WAN technology that is designed to establish connection between two nodes over a variety of network mediums. Features 1. It has built-in error detection. 2. Monitoring the quality of the link before sending frames. 3. Capability to encapsulate frames and carry them over various layer2 WAN technologies … Continue reading An introduction to Point-to-Point Protocol →

Frame relay: Multilink point to point frame relay

Reference: http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_mfr.html Multilink Frame Relay (FRF.16.1) 1. This technology aggregates multiple number of physical serial interfaces into one bundle. a. This provides link redundancy i.e. if a physical link of a bundle has failed, the frame relay link will still be available. b. This also provides bandwidth aggregation from multiple serial interfaces. (See http://www.cisco.com/en/US/docs/ios/12_2s/feature/guide/fs_mfr.html#wp1054102) 2. The aggregated … Continue reading Frame relay: Multilink point to point frame relay →

Frame-relay: Inverse ARP

Frame relay is a packet switching technology that emulates like a switch. Switch uses ARP broadcast to find out the mac address of the host so that switch can forward the frame to the destined switch port. Frame relay however does not have broadcast ability, it uses encapsulation technique either Cisco or IETF encapsulation format. … Continue reading Frame-relay: Inverse ARP →

Spanning Tree Protocol (802.1D)

This protocol prevents bridging loop created by redundant links within switch network. STP calculation will make switch/es block its own port so that the switch path is one straight line and not a loop. This is perhaps the most confusing concept in switch, it is not extremely difficult but many terminologies and the method on … Continue reading Spanning Tree Protocol (802.1D) →

Catalyst Switch: Turn off trunking negotiation

To turn off dynamic trunking protocol (DTP) and use dot1q standard. It is recommended to turn off trunking protocol and put vtp to transparent mode, this is because a newly introduced Catalyst switch may form undesired switch topology and if the newly introduced Catalyst switch has a vtp revision number higher than the current switch … Continue reading Catalyst Switch: Turn off trunking negotiation →

Catalyst Switch: No trunks is formed

I have connected two Cisco Catalyst 3560 switches together by a pair of fibre cables. No trunk was formed. The default interface configuration for Catalyst 3560 is dynamic auto, in Catalyst 3550 the default was dynamic desirable. Dynamic desirable is actively negotiating a trunk with another cisco catalyst switch, whereas dynamic auto is passively waiting … Continue reading Catalyst Switch: No trunks is formed →