At 12:44 PM -0500 1/15/02, Chuck Larrieu wrote: >interesting question. came up in a customer meeting the other day as well. > >IMHO, this gets down to design preference.
Agreed. As you suggest, there's art as well as science here. >I am of the school of thought >that there needs be some way of getting to any router in a network ( design >permitting, cost permitting ), and that each router in a network needs some >unique and easily identified pneumonic. > >So IMHO, one should use loopbacks, numbered according to some rational >scheme, and that those "routes" should be advertised.IMHO This should be >true, no matter what routing protocol you are using. > >However, others will ask whether in a 5000 router domain, you want 5000 >extra routes in your tables. That is a valid counterargument. If you have that many routers, you presumably have a hierarchical design with summarization. Using Cisco's conservative number of routers per OSPF area, allocate 128 addresses, as part of an aggregatable block, per area. This gives 39+ blocks. If one assumes stubby areas, you'd get a maximum of 128 additional routes per nonzero area, plus 40 extra routes in area 0.0.0.0. 40 areas, however, is a lot for a single OSPF domain. When I've dealt with networks of this size, I've separated them into multiple OSPF domains linked by a backbone of backbones, either BGP or statically routed. That backbone of backbones, of course, gives the potential for additional aggregation. > >Using the RID command under the OSPF process, you can set up a rational >identification scheme. The RID does not necessarily have to be related to >interface numbering. But then you have the issue of correlating RIDs to the >addresses one actually uses to get to the router in question, making it a >bit more complicated to find things when you need to. That's why I like the RID to be the "address of last resort" to reach the router. > >JMHO. > >Chuck > > > > >""john smith"" wrote in message >[EMAIL PROTECTED]">news:[EMAIL PROTECTED]... >> Hi, >> Is there reason one would prefer loopback address for router ID when using >> Ospf over the router id command that can be used under "router ospf " and >> vice versa. Is there a need to advertise the router IDs in OSPF. Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=32048&t=32022 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
