Howard C. Berkowitz wrote: > > At 1:40 AM +0000 1/8/03, The Long and Winding Road wrote: > >""William Li"" wrote in message > >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... > >> Hi group > >> > >> > >> > >> I just happened to find there is an advertise option > could be added > >> in "area area-id range ip-address mask" command. The > command could be > >> like this "area area-id range ip-address mask advertise". > My question > >> is, will there be any functional difference between with > and without > >> this option. As per DOC CD, option "advertise" means: Sets > the address > >> range status to advertise and generates a Type 3 summary > link-state > >> advertisement (LSA). But by default, when we generate a > summary address > >> in ABR without any options, the summary address will be > advertised > >> automatically, am I right? > > > > > >you are correct. > > > >if it is any help, Parkhurst states that the two commands area > x range and > >area x range advertise are equivalent. > >there is no difference in behaviour that I have determined in > my own humble > >experiments. > > Historically, when Cisco is thinking of changing a default, the > show > config commands will start displaying the current default > (either xxx > or no xxx). Later, a command to change the default will be > made > available, and the show command will show however the option is > set. > Eventually, the new default will stop displaying unless an > explicit > command is configured. > > Now, there are two ways I've seen an ABR behave when some of > the > more-specifics of a summary disappear from the LSDB. On Cisco, > the > summary continues to be advertised. This increases > black-holing but > also improves stability. > > In Bay/Wellfleet/Nortel RS, if some more-specifics disappear, > the ABR > stops advertising the summary and only passes the available > more-specifics. This technique does avoid blackholes but > causes more > churn. > > Both interpretations/implementations have valid applications, > and > I've always wished Cisco supported both. I wonder if we have > seen a > slightly warped command release strategy here, and there is a > conditional "no-advertise" in the works that will allow the > Nortel-like behavior as well as the Cisco behavior. > > Eh-hem. >From the 12.2 IOS command reference.
area area-id range ip-address mask [advertise | not-advertise] [cost cost] not-advertise (Optional) Sets the address range status to DoNotAdvertise. The Type 3 summary LSA is suppressed, and the component networks remain hidden from other networks. Was that what you were after? I've never tried using this command - the description sounds like it just plain doesn't advertise it, whether more-specifics are around or not (why would you want that behaviour? To suppress all knowledge of the networks?) Perhaps it also needs a "conditional-advertise" option? It's been around since at least 12.0 - maybe longer. JMcL Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=60578&t=60550 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
