Wednesday, July 4, 2012

ccna tips 5

Core layer: Considered the backbone of the network (high-end switches, high-speed cables). Concerned only with speed and reliable delivery of data. No packet filtering happens here.

Distribution layer (Workgroup layer): Ensures packets are properly routed between subnets and VLANs using LAN-based routers and Layer 3 switches.

Access layer (Desktop layer): Deals with connecting workstations to the network with switches and hubs.

The original Spanning-Tree protocol was created by Digital Equipment Corporation (DEC) which is now part of Compaq. The IEEE created its own version called IEEE 802.1d which is not compatible with the original version.

Cisco enhanced the original 802.1d specification with features such as Uplink Fast, Backbone Fast, and Port Fast to speed up the convergence time of a
bridged network. However, these new features are proprietary, and can only be configured on Cisco switches.

In Transparent mode switch just forwards update sent by other switches without reading it. It doesn’t update its VLAN database so the Configuration Revision doesn’t increase.

Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol for negotiating trunking on a link between two devices and for negotiating the type of
trunking encapsulation (802.1Q) to be used.

This micro-segmentation performed by the switch cuts the collision domain down so that only two nodes coexist within each collision domain.

You can have more than one static route in your routing table.

lmi sud be sent by dce and sud be received by dte

Two ways to discover neighbors on an NBMA network: static neighbor, point-to-multipoint

Switches do not use a shared medium as opposed to hubs. Computers connected to a switch port can transmit data simultaneously without having the need to wait for other PC’s to complete data transmission.

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