Network Layer Flashcards
Basic operations of Network Layer
- Addressing end devices
- Encapsulation
- Routing
- De-encapsulation
Does src and dest IP change (if there is no NAT)
No, it stays the same. (unlike MAC)
IP characteristics
- Connectionless
- Best Effort
- Media independent
What does Connectionless mean in context with IP?
no connection is established before sending data (TCP would be connection-oriented)
What does Best effort mean in context with IP?
- Delivery is not guaranteed
- No mechanism to resend
IPv4 Fragmentation causes…
latency
IPv4 Fragmentation
Layer 3 splits the IPv4 Packet into smaller units (MTU)
How to check if NIC is alive?
ping 127.0.0.1
Ping to internal IPs works, external not, what is wrong?
Default Gateway
You replace a Router with a new one with the same IP. The connection to it doesn’t work, what could be the problem?
ARP-Table has still the old MAC linked to this IP.
Other word for Default Gateway
Last resort
3 types of Routing Table entries
- Directly connected
- Remote (static)
- Default Route
2 types of routing entries
- static
- dynamic
Where is static routing used and why is it used?
- small networks
- less resources needed (from the router)
What does Dynamic Routing
- chooses best path to destination
- dynamically adapts to topology changes
What is a disadvantage of static routing?
it doesn’t adapts to topology changes or during an outage.
You want to forward another private IP to a specific Router over the Internet, what do you configure?
a static route for this IP or IP net to the public IP of the router.
