HP 3500YL - Manual (Page 230)

IP Routing Features
Configuring OSPF
Equal Cost Multi-Path Routing
The Equal Cost Multi-Path (ECMP) feature allows OSPF to add routes with
multiple next-hop addresses and with equal costs to a given destination in the
Forwarding Information Base (FIB) on the routing switch. For example, if you
display the IP Route table by entering the
show ip route command, multiple
next-hop routers are listed for the same destination network (21.0.9.0/24) as
shown in Figure 5-22.
ProCurve> show ip route
IP Route Entries
Multiple next-hop gateway
addresses are displayed for the
destination network 21.0.9.0/24.
Destination Gateway Sub-Type
1
1
1
1
IntraArea 2
2 ospf
VLAN Type Metric Dist.
------------------ --------------- ---- --------- ---------- ---------- -----
1.0.0.0/8 10.0.8.1
1 static 1
10.0.8.0/21 DEFAULT_VLAN 1 connected 0
12.0.9.0/24 VLAN3 3 connected 0
15.0.0.0/8 10.0.8.1 1 static 1
21.0.9.0/24 162.130.101.2 2 ospf 110
21.0.9.0/24 162.130.101.3 2 ospf IntraArea 2 110
21.0.9.0/24 162.130.101.4 IntraArea 2 110
127.0.0.0/8 reject static 0 0
127.0.0.1/32 lo0 connected 1 0
162.130.101.0/24 VLAN2 2 connected 1 0
Figure 5-22. “Example of “show ip route” Command Output with Multiple Next-
Hop Routes
For a given destination network in an OSPF domain, multiple ECMP next-hop
routes can be one of the following types.
■ Intra-area (routes to the destination in the same OSPF area)
■ Inter-area (routes to the destination through another OSPF area)
■ External (routes to the destination through another autonomous system)
Multiple ECMP next-hop routes cannot be a mixture of intra-area, inter-area,
and external routes. For example, in Figure 5-22, the multiple next-hop routes
to network 21.0.9.0/24 are all intra-area.
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