Tim Champion wrote: > > When calculating the metric of an IGRP route (with non-default > 'K' values) > which load and reliability values does one use? Do you use the > highest, > lowest or average value for the entire route?
When calculating the composite metric, IGRP and EIGRP use the heaviest load on any segment in the route. The concern is any bottlenecks. You wouldn't want a router to select a path that on average has a reasonable load, but also has one link that is overloaded. This could happen if you used an average. And you definitely wouldn't want it to choose a path with the highest load. So they use the lowest load of any segment, which they pass to each other in Update packets. As you probably know, load isn't used at all unless you configure the metric weights command. Reliability is similar. It's the worst reliability of any segment in the path. You wouldn't want a router to select a path that on average had good reliability, but also had a link in the middle somewhere that was dropping packets like crazy. As you probably know, by default reliability is not used unelss you use the metric weights command. IGRP and EIGRP also use the lowest-bandwidth segment on the route to a network. The concern, again, is any bottlenecks. You wouldn't want a router to select a path that had some high-bandwidth links if there was still a dial-up modem connection somewhere in the path. Each router reports the bandwidth (which is configurable at router interfaces) in Update packets. The lowest is selected and passed on. Delay, on the other hand, is a sum of all the delays for outgoing interfaces in the path to the network. Did you already find this paper on IGRP by Rutgers: http://www.cisco.com/warp/public/103/5.html It doesn't have all the details, but is still a good read. Priscilla > > Also if anyone could point me to a document on the above it > would be > appreciated. > > > Many thanks in advance. > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=66082&t=66062 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
