The metric which determines performance due to delay is the metric of ” hops”. The number of hops is a measure of how many routers are involved in delivering packets. Hops are additive, so a two-hop path has two routers between a source device and destination device, three-hops have three routers, and four-hops have four.
In terms of performance, routes with fewer hops will be less delayed as they traverse fewer devices to reach their destination. For instance, when transferring data over the Internet from one continent to another using conventional undersea cables requires approximately six times the bandwidth capacity than using satellites due to their higher latency (delay).
This is due to the distance which the optical signal has to travel between stations on the continents as well as other networking equipment along the way.
The network diameter (the longest route) of an internetwork is a measure of how many hops separate all possible pairs of devices in that internetwork. For instance, if there are six devices, A,B,C,D,E and F in an internetwork with each device connected to its two nearest neighbours then a path from A to F would have three hops (A->B->C and C->D->E and E->F). The network diameter would be 4 since there are four hops between all pairs of nodes in the Internetwork.
The larger the network diameter, the more closely all possible pairs of nodes in an internetwork are connected to one another. Therefore, a longer route (fewer hops) will take less time due to fewer potential delays caused by passing through routers and network segments which do not contain devices of interest.
In addition, Internet service providers may require circuitous paths as part of an internetwork such that multiple very short-haul paths share the same longest-distance path.
In this case, a long route between any two points in an internetwork would almost always have at least two intermediate stops on either side of the device between which the packets must be transmitted.
Some routing protocols entirely ignore the topology of internetwork (e.g., RIP, OSPF, EIGRP) but have no way to understand the network diameter. In this case they will attempt to “optimise” for shortest-route performance even if this requires more hops or a longer path overall.
Wireless networks have their own special considerations: interference, range, and latency. Wireless devices are often collocated with the traffic source and will not see all delays for a given link as do circuit-switched devices such as phones or modems connected to local telephone lines in a home or office.
In terms of wireless network performance, the number of hops determines latency. For a wireless network, this means that eliminating delays caused by transmission through other devices may increase performance without increasing size or cost.
Some wireless networking protocols modify routes to introduce logical bottlenecks (e.g., hub and spoke; star). This allows original path selection to remain as simple as possible and does not affect performance overall although it will cause more hops in some cases depending on which route is chosen within each hop group. These are usually discarded after routing entries are updated but may be retained in the routing table for some time because of caching issues.
