From: Brian Dennis (bdennis@internetworkexpert.com)
Date: Wed Jun 14 2006 - 15:41:16 ART
First off there is no "best" way to do something in the CCIE lab. There are only ways that get you points and ways that don't get you points. You can't get "style" points in the CCIE lab so any solution that works and meets the requirements is what we are looking for ;-)
Understanding what OSPF network types work with what other OSPF network types is key in this situation. Network types that use a DR will neighbor with each other assuming the hello/dead intervals are synced. Network types that do NOT use a DR will neighbor with each other assuming the hello/dead intervals are synced.
Your particular question can't be accurately answered without knowing how the Frame Relay network is setup. If R6 is a P2P subinterface over a multipoint or physical interface then that changes everything.
If all of the routers are using physical interfaces or multipoint subinterfaces we know that the default OSPF network type will be non-broadcast. Assuming that we have the freedom to do whatever we want (i.e. real world) we would use the OSPF network type of point-to-multipoint since this is the exact situation that point-to-multipoint was designed for (hub and spoke).
Now with your requirements we cannot change the default OSPF network type on R6. If R6 is using a physical or multipoint interface then we could use the neighbor command on the hub and leave everything else to the default. Another option would be to set the hub's OSPF network type to broadcast and alter its hello interval (from 10 to 30) to match the other routers that are using non-broadcast. If R6 is a P2P subinterface then we would set the hub's OSPF network type to point-to-multipoint and ensure that the hello intervals are synced.
These option are leaving out the possibility of using PPPoFR or a GRE to solve the issue but they are left out since you would normally using them as more of "last resort" options.
HTH,
Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
bdennis@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
Toll Free: 877-224-8987
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-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Mike O
Sent: Wednesday, June 14, 2006 10:55 AM
To: ccielab@groupstudy.com
Subject: interfaces w/ OSPF network types
I have a question that I thought I would throw out.
If you have a situation where some of your frame-relay interfaces are allowed to have the ospf network type defined and then some not. Whats the best way to configure that? For example say you have a hub and spoke with R1 as the hub as R4,5 and 6 as the spoke. R6 cannot use "ip ospf network" but everyone else can. Do you just use neighbor? or better yet say you must use network type on R4.
Is it always better to fall back and use the neighbor command when you can't get anything else to work? considering you are allowed to use the neighbor command in the given section.
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