Chapter 9 - Network Optimization Flashcards
Committed information rate (CIR)
The CIR of an interface is the average traffic rate over the period of a second.
Common Address Redundancy Protocol (CARP)
An open standard variant of HSRP, which provides first-hop router redundancy.
Congestion avoidance
If an interface’s output queue fills to capacity, newly arriving packets are discarded (or tail dropped). Congestion avoidance can prevent this behavior. RED is an example of a congestion-avoidance mechanism.
Congestion management
When a device, such as a switch or a router, receives traffic faster than it can be transmitted, the device attempts to buffer (or store) the extra traffic until bandwidth becomes available. This buffering process is called queuing or congestion management.
Differentiated services (DiffServ)
As its name suggests, DiffServ differentiates between multiple traffic flows. Specifically, packets are marked, and routers and switches can then make decisions (for example, dropping or forwarding decisions) based on those markings.
Integrated services (IntServ)
Often referred to as hard QoS because IntServ can make strict bandwidth reservations. IntServ uses signaling among network devices to provide bandwidth reservations. Resource Reservation Protocol (RSVP) is an example of an IntServ approach to QoS. Because IntServ must be configured on every router along a packet’s path, a primary drawback of IntServ is its lack of scalability.
Jitter
The uneven arrival of packets.
Latency
The measure of delay in a network.
Link efficiency
To make the most of the limited bandwidth available on slower speed links, you might choose to implement compression or link fragmentation and interleaving (LFI). These QoS mechanisms are examples of link efficiency mechanisms.
Marking
Alters bits within a frame, cell, or packet to indicate how a network should treat that traffic. Marking alone does not change how a network treats a packet. Other tools (such as queuing tools) can, however, reference markings and make decisions (for example, forwarding decisions or dropping decisions) based on those markings.
Policing
Instead of making a minimum amount of bandwidth available for specific traffic types, you might want to limit available bandwidth. Both policing and traffic-shaping tools can accomplish this objective. Collectively, these tools are called traffic conditioners. Policing can drop exceeding traffic, as opposed to buffering it.
Reliability
The measure of how error-free a network transmits packets.
Traffic shaping
Traffic shaping delays excess traffic by buffering it as opposed to dropping the excess traffic.
