From: Richard Dumoulin (richard.dumoulin@vanco.es)
Date: Sun Apr 11 2004 - 14:51:58 GMT-3
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,
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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