Chapter 4: The Network Layer: Data Plane

These flashcards cover the key concepts and definitions related to the Network Layer data plane as discussed in Chapter 4.

What two main parts is the Network Layer decomposed into?

data plane and the control plane.

What is the key function of the data plane in the Network Layer?

The data plane is responsible for forwarding packets from an input link to an output link.

What is the difference between forwarding and routing?

Forwarding is a per-router function for moving packets, while routing is the network-wide process of determining paths for packets.

What is a forwarding table?

The forwarding table links the data and control planes, specifying the local forwarding behavior of a router.

What components typically make up a traditional router?

A traditional router consists of input ports, output ports, a switching fabric, and a routing processor.

What are input ports in a router responsible for?

Input ports perform link-layer and network-layer processing, including looking up the output port for incoming datagrams.

What is the role of the switching fabric in a router?

The switching fabric moves packets from input ports to the appropriate output ports.

Name some packet scheduling disciplines.

FIFO (First-In, First-Out), Priority Queuing, Round Robin (RR), and Weighted Fair Queuing (WFQ).

what’s Packet scheduling?

Disciplines determining which packets get serviced next:

What does the IP service model guarantee?

The IP service model provides a best-effort delivery service without guaranteeing delivery, order, or data integrity.

What key fields are included in the IPv4 Datagram Format?

Key fields include Header Checksum, Time-to-Live (TTL), and Protocol Field.

What is the purpose of the Time-to-Live (TTL) field in an IPv4 datagram?

TTL is decremented at each router and if it reaches zero, the datagram is dropped to prevent infinite loops.

What is CIDR and why is it important?

CIDR (Classless Interdomain Routing) allows IP addresses to be defined with a network prefix, enabling route aggregation and reducing the size of forwarding tables.

Explain Network Address Translation (NAT).

NAT allows a private network to use a single public IP address for outbound traffic by mapping local IP address and port pairs to public pairs.

What is the purpose of IPv6?

IPv6 is designed to replace IPv4, providing a larger address space (128 bits) and a simplified header.

What does Match-Plus-Action in generalized forwarding involve?

Match-Plus-Action involves matching values across multiple header fields and performing corresponding actions like forwarding, dropping, or sending to the routing processor.

What is OpenFlow?

OpenFlow is a protocol that implements generalized forwarding using flow tables instead of just forwarding tables.

what are subnets?

Isolated networks defined by interfaces and physical media

What does Output ports do?

Stores packets before transmission onto the outgoing link, perform link-layer and physical-layer functions. Queuing and packet loss can occur.