Router metrics are configuration values used by a
router to make routing decisions. A ''metric'' is typically one of many fields in a
routing table. Router metrics help the router choose the best route among multiple feasible routes to a destination. The route will go in the direction of the gateway with the lowest metric.
A router metric is typically based on information such as
path length,
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
,
load
Load or LOAD may refer to:
Aeronautics and transportation
*Load factor (aeronautics), the ratio of the lift of an aircraft to its weight
*Passenger load factor, the ratio of revenue passenger miles to available seat miles of a particular transpo ...
,
hop count, path cost,
delay,
maximum transmission unit
In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size that ...
(MTU),
reliability and communications cost.
Examples
A metric can include:
* measuring link utilization (using SNMP)
* number of hops (
hop count)
* speed of the path
* packet loss (router congestion/conditions)
*
Network delay
Network delay is a design and performance characteristic of a telecommunications network. It specifies the latency for a bit of data to travel across the network from one communication endpoint to another. It is typically measured in multiples ...
* path reliability
* path
bandwidth
Bandwidth commonly refers to:
* Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range
* Bandwidth (computing), the rate of data transfer, bit rate or thr ...
* throughput
NMP - query routers*
load
Load or LOAD may refer to:
Aeronautics and transportation
*Load factor (aeronautics), the ratio of the lift of an aircraft to its weight
*Passenger load factor, the ratio of revenue passenger miles to available seat miles of a particular transpo ...
*
Maximum transmission unit
In computer networking, the maximum transmission unit (MTU) is the size of the largest protocol data unit (PDU) that can be communicated in a single network layer transaction. The MTU relates to, but is not identical to the maximum frame size that ...
(MTU)
* administrator configured value
In
EIGRP, metrics is represented by an integer from 0 to 4,294,967,295 (The size of a 32-bit integer). In
Microsoft Windows XP
Windows XP is a major release of Microsoft's Windows NT operating system. It was release to manufacturing, released to manufacturing on August 24, 2001, and later to retail on October 25, 2001. It is a direct upgrade to its predecessors, Wind ...
routing it ranges from 1 to 9999.
A metric can be considered as:
* additive - the total cost of a path is the sum of the costs of individual links along the path,
* concave - the total cost of a path is the minimum of the costs of individual links along the path,
* multiplicative - the total cost of a path is the product of the costs of individual links along the path.
Service level metrics
Router metrics are metrics used by a router to make routing decisions. It is typically one of many fields in a routing table.
Router metrics can contain any number of values that help the router determine the best route among multiple routes to a destination. A router metric typically based on information like path length, bandwidth, load, hop count, path cost, delay, MTU, reliability and communications cost.
See also
*
Administrative distance
Administrative distance (AD) or route preference is a number of arbitrary unit assigned to dynamic routes, static routes and directly-connected routes. The value is used in routers to rank routes from most preferred (low AD value) to least pre ...
, indicates the source of routing table entry and is used in preference to metrics for routing decisions
References
{{reflist
External links
Survey of routing metrics
Computer network analysis
Network performance
Metrics