I partially agree. I believe classful routing protocols (RIPv1 and IGRP) do not support VLSM but the do support subnet masking. If the network is directly attach it will use its interface subnet mask to derive the networks subnet mask. Therefore the mask for the must be consistent throughout the network. If the network is not directly attached it will only use major class to search the routing table.
Example Network AA
10.1.0.0 255.255.0.0 correct
10.2.0.0 255.255.0.0 correct
10.4.0.0 255.252.0.0 not correct
172.16.1.0 255.255.255.0 - correct
172.16.2.0 255.255.255.0 - correct
172.16.4.0 255.255.252.0 not correct
During route lookup classful routers will first match major network number then match subnet mask. If subnet is not listed the packet is dropped. This occurs even if a default route exists. Appling the ip classless to classless and classful routing protocols removes this behavior.
Classless routing protocols (RIPv2, OSPF, and EIGRP) perform longest bit match searches in the routing table. They support VLSM. And they also support the all-zeros and all-ones subnet is usable with the ip subnet-zero command.
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.