From: Peter van Oene (pvo@usermail.com)
Date: Sun Apr 11 2004 - 23:53:39 GMT-3
At 01:51 PM 4/11/2004, Richard Dumoulin wrote:
>Allan,
>
> I would use 0.0.0.0 to go faster on the exam but I would be careful when
>configuring asbr's as mentioned by Serran on multiaccess interfaces.
>
>I have just found a case where using the wild card mask instead of 0.0.0.0
>was not appropriate. Redistribution was being done on the asbr but the only
>way to have full connectivity was to have the asbr advertise his own address
>(forwarding address) for the redistibuted routes,
Do you know why this is? Ie, what is the issue at play here?
>Regards
>
>--Richard
>
>
>-----Original Message-----
>From: Scott Morris [mailto:swm@emanon.com]
>Sent: domingo, 11 de abril de 2004 15:30
>To: 'Allan Wells'; ccielab@groupstudy.com
>Subject: RE: advertise ospf as 192.168.1.1 /29 0.0.0.0 area 0 and not
>0.0.0.7
>
>
>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.
>
>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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