Anyone can advise why can not use RIP, IS-IS and IGRP in case I was uing NBMA like FrameRelay or X.25? While I can use EIGRP and OSPF with NBMA?
>> What those other methods (other than broadcast)that can let the router knows to whom to send (specially in the beginning as the router does not know whom beside him)?
it is manually configured as for BGP
frame-relay multipoint interface NBMA
no ip addr
int sere0/0.100 multipoint
ip address 172.16.80.1 255.255.255.240
frame-relay map ip 172.16.80.2 102 broadcast
frame-relay map ip 172.16.80.3 103 broadcast
! the broadcast keyword would allow to map RIP hellos without using the neighbor command
similar setups are possible for EIGRP and OSPF (OSPF requires also configuration of appropriate network-type)
Hope to help
>> From the other side, why I can not use IS-IS with NBMA if I disabled the split horizon (same as RIP)?
IS-IS is link state like OSPF there is no split horizon concept in both of them: they flood data structures (OSPF LSA for example) in all links that are in the same area.
Split horizon is a distance vector concept that says do not advertise an IP subnet out the interface it has been learned.
OSPF has many network types that allows to deal with NBMA, IS-IS has only two network types: broadcast (LAN) and point-to-point (serial) so as correctly noted by Laurent it can be used only in an NBMA with a full mesh (where each router can reach every other router without going via a third one)
You can use the neighbor statement in RIP even together with passive-interface (that will stop broadcast advertisements)
As I noted IGRP is not current anymore.
Hope to help
>> ISIS worked over NBMA but only in a fully-mesh topology
Thanks for your correction my memory betrayed me
ISIS worked over NBMA but only in a fully-mesh topology as it supports only pt-2-pt or broadcast network type. Please see the following link for more information:
RIP/IGRP works as well over NBMA as split-horizon is disabled by default with FR encapsulation (not for X25). If you can't send multicast update, you can switch to unicast update (neighbor + passive interface commands). Also if you have a lot of neighbor and are sending multicast updates, you may have to tune the broadcast queue.