At 1:47 PM -0500 3/15/02, John Green wrote: >C and D (info about links and routes) is always true >for all routing protocols because that is what is >routing is all about. > >A (periodic updates): RIP does that for sure. not sure >for ospf and bgp. >B: hello mechanism... not sure if all do, but i guess >it is true as well (guess though)
One fairly general rule is that hellos and periodic updates are mutually exclusive. In the early distance vector protocols, RIP and IGRP, the lack of updates was used to detect link and distant router failures. The advent of hello protocols made it practical to send updates only, since as long as you were receiving hellos, you could assume nothing had changed. There are some special cases, such as periodic reflooding in OSPF as a reality check. In operation, many ISPs disable BGP keepalive and rely on an IGP and/or lower layers to detect failures. BGP keepalive is generally too slow to be useful. So: RIP: Periodic update (30 sec), no hello IGRP: Periodic update (90 sec), no hello OSPF: Updates only (30 minute reflood), hello EIGRP:Updates only, hello ISIS: Updates only, hello BGP: Really not comparable > > >--- mlh wrote: >> Hi, there, >> >> The following question has been given a reference >> answer : ABCD >> But I am not sure: All routing protocols update >> periodically? >> All of them send hello message? what is the >> difference between >> information about links and routes? >> >> What are some characteristics of routing protocols? >> >> A - Send periodic updates. >> B - Have a separate hello mechanism. >> C - Exchange information about links. >> D - Exchange information about routes. >> E - No answer is correct >[EMAIL PROTECTED] > > >__________________________________________________ >Do You Yahoo!? >Yahoo! Sports - live college hoops coverage >http://sports.yahoo.com/ Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=38463&t=38393 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
