Static routing is one of the easiest way to define reachability among the different networks but is only helpful if you are in stub network (A network which is having a single exit point) or is usefully for small networks. Static routing can be defined with different types of exit interface. Below is the various types of defining static routing.
1.Static routes can have next hop address of an IP Address:-
ip route 10.2.2.0 255.255.255.0 10.1.2.1. Defining this type of route causes the RIB and CEF to recursively lookup the correct layer 2 header to rewrite onto the packet. As long as the next hop is reachable, the router assumes the destination through that next hop is reachable.
2.Static routes can have next hop address as point to point interface address:- ip route 10.2.2.0 255.255.255.0 serial0. The RIB and CEF point the route directly at the point-to-point interface. For each packet destined to 10.2.2.0/24, the layer 2 rewrite header is set up to reach the other end of the point-to-point link. As long as the interface is up, the router assumes the destination is reachable through that interface.
3.Static routes can have next hop address as broadcast interface:- ip route 10.2.2.0 255.255.255.0 fa0/0. If you point a static route to a broadcast interface, the route is inserted into the routing table only when the broadcast interface is up. This configuration is not recommended because when the next hop of a static route points to an interface, the router considers each of the hosts within the range of the route to be directly connected through that interface. With this configuration, router assumes all the interfaces are directly connected and performs the ARP request for every destination. This configuration increases the IP Input and consumes lot of memory to store the arp entries. This configuration requires enabling proxy ARP on routers, if it is not enabled will lead to drop the packets.
For default routes with outgoing interface as broadcast interface could lead to 2 raise to power 32 entries in the ARP table.
1.Static routes can have next hop address of an IP Address:-
ip route 10.2.2.0 255.255.255.0 10.1.2.1. Defining this type of route causes the RIB and CEF to recursively lookup the correct layer 2 header to rewrite onto the packet. As long as the next hop is reachable, the router assumes the destination through that next hop is reachable.
2.Static routes can have next hop address as point to point interface address:- ip route 10.2.2.0 255.255.255.0 serial0. The RIB and CEF point the route directly at the point-to-point interface. For each packet destined to 10.2.2.0/24, the layer 2 rewrite header is set up to reach the other end of the point-to-point link. As long as the interface is up, the router assumes the destination is reachable through that interface.
3.Static routes can have next hop address as broadcast interface:- ip route 10.2.2.0 255.255.255.0 fa0/0. If you point a static route to a broadcast interface, the route is inserted into the routing table only when the broadcast interface is up. This configuration is not recommended because when the next hop of a static route points to an interface, the router considers each of the hosts within the range of the route to be directly connected through that interface. With this configuration, router assumes all the interfaces are directly connected and performs the ARP request for every destination. This configuration increases the IP Input and consumes lot of memory to store the arp entries. This configuration requires enabling proxy ARP on routers, if it is not enabled will lead to drop the packets.
For default routes with outgoing interface as broadcast interface could lead to 2 raise to power 32 entries in the ARP table.
ABOUT AUTHOR: Shivlu jain
System Engineer at Cisco Systems
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