Thanks, although I'm not sure I completely understand it now... I will reread tomorrow.
Eric ----- Original Message ----- From: "cebuano" To: "'ericbrouwers'" Sent: Thursday, January 23, 2003 1:09 AM Subject: RE: Why is OSPF E1 route preferred over E2 route? [7:61619] > Eric, > This is relevant only when you have multiple ASBRs advertising the same > destination into the area. The default Type 5 LSA into the area is E2. > However, if the router hears both E1 and E2 advertisements, then E1 will > be preferred. The order from most to least preferred is Intra-area, > Inter-area, E1, then E2. As far as cost, the least cost path is ALWAYS > preferred. This is one way of influencing which path is actually chosen > by changing the type of External LSA that you configure to be advertised > into the area. > > Let me know if you need further clarification. > Elmer > BTW - your questions remind me of the same questions I had when I was > studying for the BSCN exam. > ----- Original Message ----- From: "bergenpeak" To: Sent: Thursday, January 23, 2003 12:29 AM Subject: Re: Why is OSPF E1 route preferred over E2 route? [7:61619] > In the docs I've read (and I think this was posted on this list as > well), one might use E2s when you've got one exit point that is always > prefered over the other(s). This might happen if you've got 2 ISPs > and one configured as a backup only. The primary exit point is always > prefered, regardless of the internal cost to get to it. > > E1s are useful when one might want to load share traffic to the exit > points. Each router computes the internal cost to each exit, and > takes the path to the closest based on internal cost. > > ericbrouwers wrote: > > > > Hi, > > > > Why is an E1 route preferred over an E2 route for the same destination? > > > > The cost of an E1 route is the sum of the external reported cost and the > > internal cost used to reach that destination. > > The cost of an E2 route is always the external cost, irrespective of the > > internal cost to reach that route. > > > > This implies that the path with the higher cost is preferred.... Is it > maybe > > because E1 routes are reflecting the real cost? They are not hiding the > > internal costs.....But if this is the reasoning behind it, why has Cisco > made > > E2 the default instead of E1???? > > > > Anyone an idea? > > > > Eric Brouwers > > > > By the way, CCNP Routing Exam Certification Guide seems to be wrong on page > > 294, chapter 6. The E2 definition is not right: > > "... > > The routes discovered by OSPF in this way can have the cost of the path > > calculated in one of two ways: > > . E1-The cost of the path to the ASBR is added to the external cost to the > > next-hop router outside the AS. > > . E2-The cost of the path to the ASBR is all that is considered in the > > calculation. This is the default configuration. This is used when there is > > only one router advertising the route and no selection is required. If both > > an > > E1 and an E2 path are offered to the remote network, the E1 path will be > > used. > > ..." Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61714&t=61619 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
