From: Ahmed (ahmed_mustafa01@excite.com)
Date: Fri Nov 28 2003 - 23:24:33 GMT-3
Brian, In a CCIE lab environment, if one is instructed to use point-to-multipoint, assume also advertise some loopback interfaces in a hub router, and as well as each of the spoke routers. Then, would would the best choice to get rid of /32 routes since they can create a problem for the ISDN between the hub router and the other end connected to some other router. I have seen these issues when I practiced some labs from IPexpert, but never got any good answer. Regards, Ahmed.--- On Fri 11/28, Brian Dennis < bdennis@internetworkexpert.com > wrote:From: Brian Dennis [mailto: bdennis@internetworkexpert.com]To: Paul.Casey@o2.com, ccielab@groupstudy.comDate: Fri, 28 Nov 2003 16:28:25 -0800Subject: RE: ospf network point-to-multipointIf you are wondering why spokes need reachability with other spokes,configure a frame relay hub & spoke network using an OSPF network type ofbroadcast or non-broadcast. Now on one of the spokes look at next hopaddress for a route advertis!
ed by another spoke. Non-broadcast:Rack12R4#sho ip route ospf | in 2.2.2.0O 2.2.2.0 [110/65] via 132.12.0.2, 00:00:13, Serial0/0^^ ^^^^^^^^^^Change the network type to point-to-multipoint and then look at the sameroute.Multipoint:Rack12R4#sho ip route ospf | in 2.2.2.0O 2.2.2.0 [110/129] via 132.12.0.1, 00:00:32, Serial0/0^^^ ^^^^^^^^^Notice how the next hop address changes. The next hop address is now the huband not the other spoke. Also note that the OSPF cost is more accurate withpoint-to-multipoint in a hub and spoke environment over using broadcast ornon-broadcast. Point-to-multipoint is taking into account the cost to reachthe hub and then the cost from the hub to the other spoke.Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)bdennis@internetworkexpert.com Toll Free: 877-224-8987Direct: 775-745-6404 (Outside the US and Canada)Internetwork Expert, Inc.http://www.InternetworkExpert.com-----Original Message-----From: Casey, Paul (6822) [mailto:Paul.Casey@o2.com] Sen!
t: Friday, November 28, 2003 3:22 PMTo: 'ccielab@groupstudy.co!
m'Cc: 'B
rian Dennis'Subject: RE: ospf network point-to-multipointBrian,What are the possible reachability issues here. Can you give an example. how without the /32 it would not functioncorrectly. I always,when shown an example understand much clearer, as Iassume most people do.Kind regards.Paul.> -----Original Message-----> From: Brian Dennis [SMTP:bdennis@internetworkexpert.com]> Sent: Friday, November 28, 2003 10:38 PM> To: navaid@rogers.com; ccielab@groupstudy.com> Subject: RE: ospf network point-to-multipoint > > Basically just don't run point-to-multipoint ;-)> > The behavior of point-to-multipoint is to advertise each end-point out as> a> /32 and suppress the advertisement of the network itself.> Point-to-multipoint does this to overcome possible reachability issues> between devices that are on the same logical subnet but do not have direct> communication (i.e. spoke to spoke communication). OSPF> point-to-multipoint> and technic!
ally loopback network types do not advertise the network> itself.> This is as per the RFC. > > If you want to suppress the /32s and advertise only the network, you would> need to use an OSPF network type other than point-to-multipoint or> configure> the network to be in its own OSPF area. After the network is put in its> own> OSPF area, use the area range command to summarize the /32s so other> routers> only see the summarized route. > > Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)> bdennis@internetworkexpert.com > Toll Free: 877-224-8987> Direct: 775-745-6404 (Outside the US and Canada)> Internetwork Expert, Inc.> http://www.InternetworkExpert.com>; > -----Original Message-----> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of> navaid@rogers.com> Sent: Friday, November 28, 2003 2:13 PM> To: ccielab@groupstudy.com> Subject: ospf network point-to-multipoint > > I ha!
ve ospf network point-to-multipoint configured between R1,R2 a!
nd R3.&g
t;
R2 is frame relay Hub and R1,R3 spoke.> In my routing table I am seeing host routes (/32) for frame interface of> R1,R2 and R3 but NO router for subnet. How do I suppress host and see only> one route for subnet which is /24.> > Thanks,> > Navaid> > _______________________________________________________________________> Please help support GroupStudy by purchasing your study materials from:> http://shop.groupstudy.com>; > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html>; > _______________________________________________________________________> Please help support GroupStudy by purchasing your study materials from:> http://shop.groupstudy.com>; > Subscription information may be found at: > http://www.groupstudy.com/list/CCIELab.html****************************************************************************************This E-mail is from O2. The E-mail and any filestransmitt!
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