exam 3 Flashcards
(36 cards)
in what types of links is the network layer implemented?
3 types:
1. wired links
2. wireless links
3. LANS
combination of software, hardware, firmware
forwarding vs routing
forwarding = local action of transferring a packet from an input port to an output port on an individual device
- data plane
routing = network-wide process that determines a packet’s path across the network from source to destination
- control plane
switching fabric definition
area/component that connects a router’s input ports to its output ports
forwarding table definition
determines the routes of packets across a network
generated by routing algorithm
link-layer protocols run at which network layer
layer 2 (link layer)
second layer from bottom
network adapter synonym
network interface card (NIC)
one-bit even parity scheme flaw
if an even number of errors occurs, the errors will be undetected
what layer are ethernet switches on
data link layer (layer 3)
NOT network layer (layer 2)
where is the network layer implemented
it’s implemented in routers in the network core AND in hosts at the network edge
data plane responsibilities (3)
- moving datagram from router input port to output port
- dropping a datagram due to congested (full) output buffer
- looking up additional bits in an arriving datagram’s header in the forwarding table
data plane vs control plane
control plane - routing (deciding where packets should go)
- runs in software
data plane - forwarding (actually sends the packets)
- runs in hardware
control plane responsibilities (2)
- monitoring and managing the configuration & performance of a network device
- computing the contents of the forwarding table
SDN stands for
software-defined networking
traditional per-router control-plane vs SDN approaches to managing/controlling network behavior
traditional = distributed control plane (each router has it own control plane)
- control plane & data plane are coupled in the same device
- routers communicate with each other
SDN = centralized control plane (control logic happens in a centralized controller)
- data planes (routers, switches) are dumb and just follow controller instructions
- routers do NOT communicate with each other
do routers message each other in traditional per-router control-plane approach?
yes, they message each other
- share their costs to reach a destination
- send info about incoming/outgoing links to other routers
what does the “best-effort” internet service model NOT guarantee? (4)
- delivery time
- bandwidth
- packet loss
- delivery order
2 router components that operate primarily in the data plane
- input ports
- switching fabric
2 router components that operate primarily in the control plane
- routing processor
- output ports
Where in a router is the destination IP address looked up in a forwarding table?
At the input port where a packet arrives
switching fabric
router’s internal network that connects its input ports to output ports
- moves packets from input to output
“match plus action” meaning
“Match plus action” means the router looks at certain fields in a packet (match), and then takes a specific action based on that match
example:
match = looks at fields like: IP address, MAC address, port number, protocol type
action = forward to a certain port, drop packet, modify packet header, send to controller (in SDN)
where does “match plus action” happen in a router?
At the input port where a packet arrives
IPv4 protocol definition
protocol that is used to identify devices & route packets across networks
- assigns 32-bit addresses (IP addresses) to devices & helps route packets from source to destination across networks
- operates at the network layer (layer 3)
IPv4 protocol principal components (3)
- Packet-handling conventions at routers (e.g., segmentation/reassembly)
- IPv4 datagram format
- IPv4 addressing conventions
