Hello everyone !
I'm just so curious about wildcard mask which is used in OSPF. I don't understand why OSPF does use wildcard mask. -.-; Please teach me. Even EIGRP has VLSM and CIDR features, but it use subnet mask, not wildcard mask.
My book says this: "A wildcard mask is necessary because OSPF supports CIDR and VLSM, unlike RIPv1 and IGRP."
example>
router(config-router)#network 192.168.0.1 0.0.0.255 area 101
actually eigrp is configured with wild card mask just like ospf.... ospf's "area range" command actually uses the subnet mask argument, where what you are referring to, ospf's "area x" command uses the wild card mask...
I dont know why IOS has this convention, but its obviously cleaner. Anyone who is configuring this stuff should know for instance
255.255.240.0 = 0.0.15.255 and 255.255.255.252 = 0.0.0.3 ... I guess cisco realized its just cleaner...Any> Hello everyone !
snipped-for-privacy@hotmail.com a écrit :
My guess:
Access-lists and ospf areas use wildcard masks because back in the days of the AGSes, every CPU cycle counted and using a wilcard mask makes the logic of deciding if a packet matches a couple of cpu cycles faster.
Secondly, wildcard masks are usually smaller when written in text (unless you are using a class A network) and back in the days of 16k nvram, using a wildcard mask meant a config that was a bit smaller.
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