Multicast and Routing Guide K/KA/KB.15.15

Figure 41 Example of OSPF ECMP multiple next-hop routing (inter-area)
However, the forwarding software distributes traffic across the three possible next-hop routes in
such a way that all traffic for a specific host is sent to the same next-hop router.
As shown in Figure 42 (page 198), one possible distribution of traffic to host devices is:
• Traffic to host 10.10.0.1 passes through next-hop router 12.0.9.2.
• Traffic to host 10.10.0.2 passes through next-hop router 13.0.9.3.
• Traffic to host 10.10.0.3 passes through next-hop router 12.0.9.2.
• Traffic to host 10.10.0.4 passes through next-hop router 14.0.9.4.
Figure 42 Example of traffic distribution on ECMP next-hop routers
Dynamic OSPF activation and configuration
OSPF automatically activates when enabled with router ospf. All configuration commands
affecting OSPF (except reconfiguring the router ID) are dynamically implemented and can be used
without restarting OSPF routing. (To reconfigure the router ID, see “Changing the router ID”
(page 117)".)
198 Open Shortest Path First Protocol (OSPF)