"Note that the only external route that has appeared is 18.104.22.168, because we did not use the subnet keyword. Remember that if the subnet keyword is not used, only routes that are not subnetted will be redistributed. In our case 22.214.171.124 is a class A route that is subnetted and it did not get redistributed."
Note also that the subnets keyword applies to redistribution into OSPF. In the example in the guide above static routes are redistributed into OSPF and subnets keyword has to do with the mask of the static routes. In this example, if static has a "classic" A, B, C class mask it will get into OSPF. If it has any other mask, it won't.
This behavior doesn't have to do with the network command you use to enable OSPF into particular interfaces. The subnets used in the interfaces where OSPF is actually running will be advertised with their corresponding masks as expected (in general).
If I remember correctly, although OSPF is classless itself, (Cisco) redistribution into OSPF w/o the subnets parameter seems to assume classful networks.
For instance, under classful rules, 10.x.x.x is class A network (or /8 VLSM). 10.1.1.0/24, under classful rules is a subnet of the 10.x.x.x class A address. To have (Cisco) redistribute 10.1.1.0/24 into OSPF requires the subnets keyword. To have (Cisco) redistribute 10.0.0.0/8 into OSPF would not.
Usually when working with (Cisco) OSPF, you'll want to use the subnets keyword when doing redistribution into OSPF.
If you wanted to redistribute 192.168.1.0/24 into OSPF, since, under class rules, it's a class C address, you wouldn't need the subnets parameter. However, 192.168.1.0/25, a class C subnet, you would need subnets parameter.
Not sure what happens with "supernets". E.g., 192.168.0.0/23. I believe subnets parameter would inject properly, but don't know what happens if subnets parameter not present. (Again, when working with VLSM/classless, you'll want to use subnets parameter.)
while doing redistribution in OSPF from any other routing protocol, then we need to specify the keyword " subnets" in redistribution command. If we do not do so, it will throw the informational message stating that "Only classful networks will be redistributed". What it means is that if we are redistributing an eigrp subnet 10.1.1.0/28 in OSPF without using "subnets" then it wont get in to OSPF. If there is a subnet 126.96.36.199/16 being redistributed in OSPF then it will enter in OSPF Topology because it is a "classful" subnet .
Therefore to successfully redistribute subnetted networks, we need to use "subnets" keyword.
This happens only in OSPF I think. Similar details can be found in below link
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.