Someone else has tackled the others, I go after #1): As you probably already know, in a lab setting, loopbacks are great for building up fictional stub networks to be used in reachability testing and summarization/filtering scenarios. For example, you can create interface loopback0 with an ip address of 10.1.1.1/24. By default, in OSPF, this loopback interface's network would be advertised as 10.1.1.1/32 even though you have specified the /24 mask. This makes for some confusion. If you specify on the loopback interface OSPF network type as point-to-point, it will force the /24 advertisement to be made instead of the /32. This makes the loopback interfaces appear to be just another stub network (not to be confused with OSPF stub area).
Ryan -----Original Message----- From: bergenpeak [mailto:[EMAIL PROTECTED]] Sent: Monday, March 04, 2002 9:00 AM To: [EMAIL PROTECTED] Subject: basic OSPF questions [7:37142] 1) A loopback address is normally advertised by OSPF as a host route. The command "ip ospf network point-to-point" enables one to specify that the interface should be advertised as a subnet route. What are the benefits for doing this? 2) Must a link cost be the same on for all routers that share the link? Is there a protocol reason for this? Some other reason? 3) In the Exstart phase, how is the master selected? Chappel's book says RID while Doyle's say highest interface IP address. Which is it? 4) I'm somewhat unclear on the Exchange and the Loading states. When a router goes into Exchange state, does it send all DDPs it knows about before processing any DDPs received from other adjancent neighbors? Thus, a router goes into Exchange state, sends all DDPs it knows about, then goes into Loading state, where it issues LSRs for LSAs it wants more details on? Is this the process? 5) Is there a difference between DBD and DDP packets? Thanks Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=37162&t=37142 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
