CISCO NETWORKING ACADEMY Chabot College ELEC Ethernet Switches

CISCO NETWORKING ACADEMY Ethernet Switch Basics Layer 2 device Uses MAC addressing to control traffic flow Supports multiple simultaneous conversations Reduces needless LAN traffic

CISCO NETWORKING ACADEMY Basics: Layer 2 Device Switch understands layer 2 addresses (MAC addresses): 00-C0-F0-56-BD-98

CISCO NETWORKING ACADEMY Basics: MAC Address Use Switch does not act like hub! Switch forwards frames based on MAC address tables.

CISCO NETWORKING ACADEMY Basics: MAC Address Use Switch “learns” MAC addresses of hosts connected to switch ports as it receives frames from those ports:

CISCO NETWORKING ACADEMY Basics: Multiple Data Paths Switch can create several simultaneous data paths or “conversations”:

CISCO NETWORKING ACADEMY Switches Reduce Needless LAN Traffic Each switch port defines a collision domain. Users on hub A only see traffic from/to their workgroup.

CISCO NETWORKING ACADEMY Advanced Features Switching matrix Addressing Multiple data rates Full duplex Port trunking VLANs Inter-switch communications Modular Chassis

CISCO NETWORKING ACADEMY Switching Matrix (Fabric) Store & Forward –stores entire incoming frame in memory buffer –performs error detection –drops bad frames –forwards good frames to destination port based on MAC address –takes time - “high latency”

CISCO NETWORKING ACADEMY Switching Matrix (Fabric) Cut-through (cross-point) –reads frame only as far as destination address field –immediately forwards all frames to destination port based on MAC address –no error checking; forwards bad frames (usually not a serious problem) –fast - “low latency” (“wire speed”)

CISCO NETWORKING ACADEMY Addressing Capability 1 MAC address per port –used with “port switching” –microsegmentation

CISCO NETWORKING ACADEMY Addressing Capability 1 MAC address per port –used with “port switching” –microsegmentation Multiple MAC addresses per port –used with “segment switching”

CISCO NETWORKING ACADEMY Multiple Data Transfer Rates Ports at 10mb/s and 100 mb/s Requires “flow control” Otherwise, a fast server on a 100 mb port could overflow the buffer of a 10 mb port.

CISCO NETWORKING ACADEMY Full Duplex Ports Ports can transmit & receive simultaneously. Useful mainly for servers. Possible only when there is one host per port (no collisions). Modern NICs “auto-sense” a full-duplex switch port & turn on FD.

CISCO NETWORKING ACADEMY Port Trunking Ports can “trunked” (linked together) to form a high bandwidth channel between switches:

CISCO NETWORKING ACADEMY Tiered Bandwidth Bandwidth can be placed where it is needed most:

CISCO NETWORKING ACADEMY VLANs Switch ports can be separated into groups called VLANs (virtual LANs)

CISCO NETWORKING ACADEMY VLANs Each VLAN forms a broadcast domain. Each VLAN is a separate Local Area Network

CISCO NETWORKING ACADEMY VLANs VLAN can be cross-connected by routers. (just like LANs)

CISCO NETWORKING ACADEMY Inter-Switch Communication Vendor-specific frame technologies allow switches to communicate. Cisco’s version is ISL (Inter Switch Link) Allows VLANs to span several switches. Hosts G, I, J, K are all part of VLAN 2:

CISCO NETWORKING ACADEMY Modular Chassis Large switches often use a modular chassis that accepts various: –“switching engines” –interface modules –power supplies The Cisco Catalyst 5000 and 5505 are examples used on the Chabot campus

CISCO NETWORKING ACADEMY Catalyst 5000 Chassis