RIP route advertising rules

Note: RIPv1 and RIPv2 protocols are mutually exclusive; you cannot run RIPv1 and RIPv2 simultaneously.

Table 1 illustrates the differences between routing rules on the basis of RIP version.

Table 1. RIP route advertising rules
Version2 Advertised destination route1 Same subnet as interface Different network from interface with same subnet mask Same network as interface regardless of subnet mask Different network from interface Same supernet as interface Different supernet from interface
RIPv1 Host Yes3 Yes3 Yes3 Yes3    
Subnet No Yes No No    
Network     No Yes    
Supernet            
Default       Yes3    
RIPv2 Host Yes3 Yes3 Yes3 Yes3 Yes3 Yes3
Subnet No Yes Yes Yes Yes Yes
Network     No Yes No Yes
Supernet     No Yes No Yes
Default       Yes5    
Notes:
  1. According to RIP design, route advertising relies on network-specific routes because they are the lowest common denominator. The network-specific routes consist of supernet, network, and subnet routes. The advertising of host specific routes is optional.
  2. RIPv1 is the default setting for the RIP version. To set to RIPv2, specify the RIP2 parameter in NCPROUTE Profile and/or on interface options in the NCPROUTE Gateways data set.
  3. The optional host specific routes are allowed to be advertised outside networks, and they are advertised in addition to the network specific routes. The option is enabled when the system -h parameter (or SUPPLY HOSTS option in NCPROUTE Gateways data set) is specified.
  4. Although it is possible to advertise only the host specific routes using the RIP filters, doing so creates network unreachable problems when some routers in the network do not support the host specific routes. These routers rely on network-specific routes.
  5. A default route has a network number of zero and is usually advertised over all network interfaces.
  6. It does not matter whether the advertised route is VIPA or not. VIPA routes follow the same advertising rules as the non-VIPA routes.
  7. Routes that are subjected to RIP filters may not be advertised at all over certain network interfaces.
Parent topic: NCPROUTE gateways