From: Jongsoo kim (bstrt2002@gmail.com)
Date: Mon Mar 28 2005 - 17:44:34 GMT-3
Hmm...
I guess I can see some logic behind of not announcing subnet but only
/32 host route.
I saw no value of annoucing subnet to resolve any reachability. I
also see at least one of the great values of these /32 host routes.
It will really help to troubleshoot to find out which spoke is down...
Also, it can save BW of F/R link because in case of a spoke is down,
the packet won't be forawrded to Hub. In other case of OPSF network
type, the packet to a down spoke will be delieverd to Hub, which will
end up fowarding it over F/R just to waste BW due to frame-relay map
command...
I guess I shuld say OSPF p2m is pretty good stuff.
Thanks Brian for tunring some lights on me.( ^ ^)
Jongsoo
On Mon, 28 Mar 2005 14:14:53 -0500, Brian Dennis
<bdennis@internetworkexpert.com> wrote:
> Jongsoo,
> Yes, as per RFC 2328 this is what you should expect to see.
> Point-to-multipoint and loopback do not advertise out the network
> itself. They only advertise out a /32.
>
> There are plenty of times that point-to-multipoint can be useful
> in the real world. If you understand what problem the
> "point-to-multipoint" network type is designed to solve, you'll
> understand where it is used in the real world.
>
> Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
>
> bdennis@internetworkexpert.com
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Direct: 775-745-6404 (Outside the US and Canada)
>
> -----Original Message-----
> From: Jongsoo kim [mailto:bstrt2002@gmail.com]
> Sent: Monday, March 28, 2005 10:49 AM
> To: Brian Dennis
> Cc: ccielab@groupstudy.com
> Subject: Re: Having a problem w/ OPSF point-to-multicast
>
> Brian.
>
> Per RFC 2328, it is normal behavior.
> For this reason, ospf point-to-multipoint may be only perfect for CCIE
> LAB not for else...
>
> Thanks
>
> Jongsoo
>
> On Mon, 28 Mar 2005 13:29:54 -0500, Brian Dennis
> <bdennis@internetworkexpert.com> wrote:
> > This is as per RFC 2328 (OSPF Version 2).
> >
> > 12.4.1.4. Describing Point-to-MultiPoint interfaces
> >
> > For operational Point-to-MultiPoint interfaces, one or
> > more link descriptions are added to the router-LSA as
> > follows:
> >
> > o A single Type 3 link (stub network) is added with
> > Link ID set to the router's own IP interface
> > address, Link Data set to the mask 0xffffffff
> > (indicating a host route), and cost set to 0.
> >
> > o For each fully adjacent neighbor associated with the
> > interface, add an additional Type 1 link (point-to-
> > point) with Link ID set to the Router ID of the
> > neighboring router, Link Data set to the IP
> > interface address and cost equal to the interface's
> > configured output cost.
> >
> > As you can see the RFC does not say anything about advertising
> > out the network, just the /32's.
> >
> > http://www.internetworkexpert.com/rfc/rfc2328.txt
> >
> > Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> >
> > bdennis@internetworkexpert.com
> > Internetwork Expert, Inc.
> > http://www.InternetworkExpert.com
> > Toll Free: 877-224-8987
> > Direct: 775-745-6404 (Outside the US and Canada)
> >
> > -----Original Message-----
> > From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
> Of
> > Jongsoo kim
> > Sent: Monday, March 28, 2005 10:21 AM
> > To: ccielab@groupstudy.com
> > Subject: Having a problem w/ OPSF point-to-multicast
> >
> > Groups
> >
> > I was doing some lab and found out something strange of OPSF
> > point-to-multicast.
> > R1 is Hub, R4 and R2 are spokes.
> >
> > R3-------R1( Hub) .1--------.2 R2( spoke 1),
> > | |
> > | |
> > | .4
> > Rip --------------.4 R4( spoke2)
> >
> > R1,R2, and R4 are OSPF A 0 (172.16.124.0/24)
> > R1 and R3 are OSPF A 13.
> > R3 and R4 are running rip.(172.16.34.0/24)
> >
> > Since OPSF p2m is configured, I saw /32 routes on routing table.
> > Every OSPF and Rip are working fine....So far so good.
> >
> > But When I do show ip route on R3,
> > I saw /32 host routes of R1,R2,R4(172.16.124.1, 2 ,4) are via OSPF
> > But 172.16.124.0/24 are learned by Rip.
> > This indicates me OSPF p2m only annouced /32 host route but the subnet
> > itself.
> >
> > But I don't believe this is correct.
> > What am I missing ?
> >
> > Here is output of R3 and
> > see "R 172.16.124.0/24 [120/1] via 172.16.34.4, 00:00:12,
> > FastEthernet0/1"
> >
> > ------------------------------R3------------------------------
> > R3#show ip route
> > Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
> > D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
> > N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
> > E1 - OSPF external type 1, E2 - OSPF external type 2
> > i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS
> > inter area
> > * - candidate default, U - per-user static route, o - ODR
> > P - periodic downloaded static route
> >
> > Gateway of last resort is not set
> >
> > 70.0.0.0/24 is subnetted, 1 subnets
> > B 70.70.70.0 [200/0] via 172.16.36.6, 00:09:14
> > 172.16.0.0/16 is variably subnetted, 19 subnets, 4 masks
> > C 172.16.140.0/22 is directly connected, Loopback1
> > O E2 172.16.25.32/27 [110/20] via 172.16.13.1, 00:00:39, Serial0/0
> > C 172.16.36.0/22 is directly connected, FastEthernet0/0
> > C 172.16.32.0/22 is directly connected, FastEthernet0/1
> > O E2 172.16.25.0/27 [110/20] via 172.16.13.1, 00:00:39, Serial0/0
> > D 172.16.16.0/24 [90/30208] via 172.16.36.6, 00:10:57,
> > FastEthernet0/0
> > O E2 172.16.17.0/24 [110/20] via 172.16.13.1, 00:00:40, Serial0/0
> > O IA 172.16.12.0/24 [110/1626] via 172.16.13.1, 00:10:48, Serial0/0
> > C 172.16.13.0/24 is directly connected, Serial0/0
> > R 172.16.124.0/24 [120/1] via 172.16.34.4, 00:00:12,
> > FastEthernet0/1
> > O 172.16.124.1/32 [110/64] via 172.16.13.1, 00:10:48, Serial0/0
> > O 172.16.124.2/32 [110/64] via 172.16.13.1, 00:10:48, Serial0/0
> > O 172.16.124.4/32 [110/128] via 172.16.13.1, 00:10:48, Serial0/0
> > R 172.16.120.0/24 [105/1] via 172.16.34.10, 00:00:02,
> > FastEthernet0/1
> > O 172.16.124.5/32 [110/128] via 172.16.13.1, 00:10:48, Serial0/0
> > O 172.16.104.0/24 [110/129] via 172.16.13.1, 00:10:48, Serial0/0
> > O E2 172.16.105.0/27 [110/20] via 172.16.13.1, 00:00:40, Serial0/0
> > D 172.16.106.0/24 [90/156160] via 172.16.36.6, 00:10:57,
> > FastEthernet0/0
> > C 172.16.103.0/24 is directly connected, Loopback0
> > 10.0.0.0/24 is subnetted, 1 subnets
> > R 10.10.10.0 [120/1] via 172.16.34.4, 00:00:13, FastEthernet0/1
> >
> > Thanks
> >
> > Jongsoo
> >
> >
> _______________________________________________________________________
> > Subscription information may be found at:
> > http://www.groupstudy.com/list/CCIELab.html
This archive was generated by hypermail 2.1.4 : Sun Apr 03 2005 - 17:56:53 GMT-3