(F) Chapter 4 Network Layer Flashcards
What is forwarding in network layer?
[Forwarding] - move packets from router’s input to appropriate router output (data plane)
What is Routing?
[Routing] determines route taken by packets from source to destination (control plane)
What is data plane?
Data plane manages the handling and forwarding of data packets at each router locally
What is traditional routing algorithms and software-defined networking (SDN)
Traditional routing algorithms: implemented in routers ,these algorithms interact within the control plane of each router to determine the best path for data packets based on network routing protocols
Software-define networking (SDN): implemented in remote servers, SDN centralizes the control of the network, allowing it to programmatically initialize, control, change, and manage network behavior through an open interface
What is network service model?
[network service model] describes the service quality a network offers, with examples like guaranteed delivery and timing, or in-order delivery for a flow of datagrams.
it is described as “best effort”, indicating no guarnatees on delivery timing, order, or bandwidth
//What is inside a router
-Where does queuing happen, what does it depend on?
-Where does forwarding table lookup happen?
Where does queuing happen, what does it depend on?
- queuing can occur at both input and output ports, and it depends on the arrival rate of datagrams and the processing speed of the router
Where does forwarding table lookup happen?
- the forwarding table lookup happens at the input ports where the router uses header field values to determine the output port for each incoming datagram
What is input port queuing?
input port queuing: refers to the process where datagrams are held in a queue at a router’s input port when they arrive faster than the forwarding rate into the switch fabric. This queuing helps manage traffic and prevents loss due to congestion, ensuring that packets are processed in an orderly fashion.
What is datagrams, switch fabric, and input port?
//Input port queuing
What is head-of-the-line (HOL) blocking
//output port queuing
What is buffering and scheduling?
[Buffering] - is the process of strong packets in memory while they await transmission. When packets arrive at an output port faster than they can be sent out on the output link, they are output in the buffer to prevent lost
however… datagrams can be lost due to congestion, lack of buffers (output port buffer overflow)
[Scheduling discipline] - refers to the method by which the router decides the order in which packets are sent from the output buffer. Priority scheduling - who gets best performance, network neutrality
//IP addressing
What is interface?
What is Physical Link?
[Physical link] - actual hardware and transmission media (like ethernet cables or optical fibers) that carry the data communications between devices devices on a network. It enables data to be transmitted across the network.
What is a Subnet?
[Subnet] is a segment of a network that shares a common address component. Devices on the same subnet can physically reach each other without the need to pass through an intervening router. This achieved by sharing a common high-order bit grouping in their IP addresses, which is subnet
What is Dynamic Host Configuration Protocol (DHCP)?
[DHCP] - serves the purpose of enabling hosts to dynamically obtain IP address from a network server when they join a network. This process supports the efficient resuse of addresses, provides configuration ease. For easy of connectivity for users across different networks.
Example:
support for mobile users who join/leave network
What Network Address Translate (NAT)?
Why IPv6
What is tunneling?
[NAT] - allows all devices on a local network to use a single public IP address for all external internet communications, making it appear as if the entire local network is a single device to the outside world
all devices in local network have 32-bit addresses in a “private” ip address space used only in local network
advantages:
- one ip addresses needed from the provided ISP for all devices
- can change addressses of host in local network without notifying outside world
- can change ISP without changing addresses of devices in local network
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[IPv6] - is a newer version of the Internet Protcol designed to address the limitations of the older IPv4 standard, primarily by using 128-bit addresses instead of 32bit improving routing and security.
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[Tunneling] - is a method used during the transition from IPv4 to IPv6 that allows for the encapsulation of IPv6 packets within IPv4 packets, enabling them to be sent over existing IPv4 infrastructre
//control plane
What is routing protocols?
[Routing protocols]: determine “good” paths (equivalently, routes), from sending hosts to receiving host, through network of routers
path: sequence of routers packets traverse from given initial source host to final destination host
“good”: least “cost”, “fastest”, “least congested”
What is Intra-AS (intra-domain)
[ Intra-AS] refers to the process of routing within a single Autonomous System (AS), which is a collection of IP networks and routers under the control of one entity that presents a common routing policy to the internet.
Intra-AS routing is the method of directing data within a single network entity, typically managed under a unified routing policy.
[Inter-AS] - involves routing between different Autonomous Systems. This is where separate entities, each with their own policies, allow their ASes to communicate with one another. This type of routing is more complex because it must consider the different policies, rules, and agreements that exist between various network operators. Inter-AS routing handles data transmission between different network entities, each governed by distinct policies and mutual agreements.
