From: Peter van Oene (pvo@usermail.com)
Date: Sun Apr 11 2004 - 14:34:17 GMT-3
At 09:29 AM 4/11/2004, Scott Morris wrote:
>You need to understand the behavior of the "network" command with IGP
>protocols (BGP is different, in a lot of things!).
>
>The network command does not specifically say which networks to advertise.
>Instead, it indicates to the router which networks will participate in the
>routing protocol. If the IP address of an interface falls within that
>range, then it is 'tagged' as participating in the routing protocol. THEN
>the actual network that the interface has will be brought in.
I'd say it says which interfaces are to participate in OSPF, vs which
networks, which is the point you make below. Newer OSPF implementations
(those that aren't IOS clones) simply have you add interfaces directly into
OSPF which is cleaner in my opinion.
>For example, if you have:
>
>E0/0 = 10.0.0.1/24
>S0/0 = 10.0.1.1/24
>S0/1 = 10.0.2.1/24
>E1/0 = 10.0.3.1/24
>
>You can say:
>
>Network 10.0.0.1 0.0.0.0 area 0 and this will only match the e0/0
>Network 10.0.0.0 0.0.0.255 area 0 and only e0/0 will fall within that range
>Network 10.0.0.0 0.0.0.3 area 0 and still only e0/0 will fall within that
>range
>Network 10.0.0.0 0.0.1.255 area 0 and both e0/0 and s0/0 will fall in here
>Network 10.0.0.0 0.0.3.255 area 0 and all four interfaces will participate
>in ospf
>Network 0.0.0.0 255.255.255.255 area 0 and every single interface on the
>router will participate in ospf
>
>There are many ways to do it, but the only thing you are indicating to the
>router is which interfaces participate in the routing protocol. The
>networks advertised comes as a later step within ospf.
>
>HTH,
>
>
>Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
>JNCIS, et al.
>IPExpert CCIE Program Manager
>IPExpert Sr. Technical Instructor
>swm@emanon.com/smorris@ipexpert.net
>http://www.ipexpert.net
>
>
>
>-----Original Message-----
>From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
>Allan Wells
>Sent: Sunday, April 11, 2004 5:34 AM
>To: ccielab@groupstudy.com
>Subject: advertise ospf as 192.168.1.1 /29 0.0.0.0 area 0 and not 0.0.0.7
>
>Hi,
>
>
>
>I have been doing some labs and looking at all the solutions.
>
>
>
>Why is it some labs setup OSPF to use wildcard mask 0.0.0.0 with say /29
>multipoint hub and spoke network
>
>As apposed to to using 0.0.0.7 mask also I tried this config with eigrp and
>theirs no problem their either what is the better way and why.
>
>
>
>I always was under the impression we need to advertise the mask of the
>network in the above example 0.0.0.7 obviously not.
>
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