2a dolan part 2 test 2 Flashcards
layer 2 switches
- frames are the PDU found at the data link layer.
- Switches are the piece of network
equipment that are primarily responsible for forwarding frames on a computer network.
two primary functions of a switch
- The first function = maintain an internal MAC Address Table aka Content Addressable Memory (CAM) Table
- The second function = make a filtering decision and forward frames out of a single destination interface that matches the destination MAC address of the frame
what is address learning?
MAC address table on a switch will associate MAC addresses to individual switchports on a switch
when will switch forward frames?
always based on destination however, if it knows address it will send to that specific switch port
if it is unable to link destination it will flood the frame (get rid of )
collision domains
are areas on a computer network where the potential for a literal collision in communication can occur
switches break up collision domains
half-duplex
Half-Duplex communication means only one side of a link can transmit at any given time
full-duplex
communication means that both sides can transmit and receive data at the same time (like a phone call)
switchport configurations
-access
when the connection going to the switch is that of a node on a computer network
-trunk
the link in question is going between a switch to another switch or a router.
one switch can talk to another switch
-routed
the port is required to act as a Layer 3 specific interface
aka no switchport mode in Cisco
hierachical internetworking model
- access layer
deployment of switches is primarily focused on directly connecting nodes, hosts, clients, and servers
handle mostly layer 2 functions such as forwarding frames, with little to no emphasis on layer 3 routing functions. aka - Desktop Layer because of this emphasis on node connectivity.
- distribution layer
deployment of switches and routers are primarily focused on accomplishing routing and filtering between the individual access layer switches
Switches capable of routing packets in addition to routers are employed here versus the strictly layer 2 switches encountered at the access layer
referred to as the Workgroup Layer
- core layer
deployment of switches and routers are primarily focused on providing high-speed and redundant connections between the routers and switches located at the distribution layer
more “powerful” switches and high-end routers for a base’s computer network are located.
broadcast storms
possibly bring down an entire base’s network if proper loop avoidance is not diligently applied beforehand
network loop
- more than one link between two pieces of network equipment that causes repetition of frames being literally loop between infinitely
broadcast frames -
- destination address of FFFF.FFFF.FFFF, sent out by individual nodes on a computer network when using a variety of different protocols
- concern on a network without proper Loop Avoidance.
CPU = will eventually reach a breaking point where it is unable to process frames entirely and quickly maxes out its CPU utilization
spanning tree protocol
STP allows for multiple paths to exist without the threat of a potential broadcast storm occurring
Spanning-Tree Topology
the protocol will assign various roles to the active switchports involved in forwarding traffic between the participating STP configured switches on a computer network
assess multiple paths between switches and** prioritize** one switchport involved in that communication path over the other
Forwarding state= allow traffic to flow
Blocking state= disallowing traffic
will designate a switch in the topology as the Root Bridge
Bridge Protocol Data Units (BPDUs)
frames sent by switches that contan information to STP + sent out every two seconds by default.
designated ports
permitted to forward on the root bridge
Root Ports
Ports permitted to forward on non-root bridge switches
