Cisco Catalyst 3750-E Series, Software Configuration Manual

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Catalyst 3750-E and 3560-E Switch Software Configuration Guide
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Chapter 40 Configuring IP Unicast Routing
Configuring OSPF
When the neighbor relationships are reestablished, the NSF-capable stack master resynchronizes its
database with its NSF-aware neighbors, and routing information is exchanged between the OSPF
neighbors. The new stack master uses this routing information to remove stale routes, to update the
routing information database (RIB), and to update the forwarding information base (FIB) with the new
information. The OSPF protocols then fully converge.
Note
OSPF NSF requires that all neighbor networking devices be NSF-aware. If an NSF-capable router
discovers non-NSF aware neighbors on a network segment, it disables NSF capabilities for that segment.
Other network segments where all devices are NSF-aware or NSF-capable continue to provide NSF
capabilities.
Use the nsf OSPF routing configuration command to enable OSPF NSF routing. Use the show ip ospf
privileged EXEC command to verify that it is enabled.
Note NSF is not supported on interfaces configured for Hot Standby Router Protocol (HSRP).
OSPF for Routed Access
With Cisco IOS Release 12.2(55)SE, the IP Base image supports OSPF for routed access. The IP services
image is required if you need multiple OSPFv2 and OSPFv3 instances without route restrictions.
Additionally, the IP services image is required to enable the multi-VRF-CE feature.
OSPF for Routed Access is designed specifically to enable you to extend Layer 3 routing capabilities to
the access or Wiring Closet.
Note OSPF for Routed Access supports only one OSPFv2 and one OSPFv3 instance with a maximum number
of 200 dynamically learned routes.
With the typical topology (hub and spoke) in a campus environment, where the wiring closets (spokes)
are connected to the distribution switch (hub) forwarding all nonlocal traffic to the distribution layer, the
wiring closet switch need not hold a complete routing table. A best practice design, where the
distribution switch sends a default route to the wiring closet switch to reach inter-area and external routes
(OSPF stub or totally stub area configuration) should be used when OSPF for Routed Access is used in
the wiring closet.
Refer to the following link for more details:
http://www.cisco.com/en/US/partner/docs/solutions/Enterprise/Campus/routed-ex.html