CCNP Switching Exam Notes: Spanning Tree Protocol (stp), Core/distribution/access Layer Switches, And Gigabyte Ethernet.

6.0 One primary function of Spanning Tree Protocol (STP) is that it prevents loops in a switched network.

7.0 If an end station in one VLAN needs to communicate with a resource in another VLAN, a router is required to route the traffic from one VLAN to another. A bridge or a layer-2 switch can only switch frames within a VLAN.


8.1 The primary function of a Core Layer is to switch traffic as fast as possible and providing connectivity between switch blocks, WAN blocks and/ or any other blocks that may be present.
8.2 The Distribution Layer is responsible for routing traffic between VLANs, Broadcast domain definition, Inter-VLAN routing, and security.
8.3 The Access Layer is responsible for Layer 2 services, such as VLAN membership, traffic filtering based on broadcast or MAC addresses.

9,0 Important properties of Core/Distribution/Access Layer switches:

9.1 The devices functioning at Access Layer are usually characterized with higher port density and lower cost. These devices also provide LAN segmentation.

9.2 High speed switching is not a characteristic of Access layer. It is usually associated with Core layer.

9.3 The Catalyst 2950 switch can provide 12,24, or 48 10/100 BaseT ports. It also provides 2 100FX or 1000BASE-X uplinks. It is a Cisco recommended for Access Layer switch.

10. Gigabit Ethernet:

The following cable lengths are specified under Gigabit Ethernet specification:
1000BaseCX: Copper shielded twisted pair: 25 meters
1000BaseT: Copper Cat 5 UTP, 4 pair: 100 meters
1000BaseSX: Multimode fiber, 62.5 micron core: 260m
1000BaseLX: Single mode fiber, 9 micron core: 3 km

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