Refer to the exhibit.
Exhibit 1
Exhibit 2
Exhibit 1 shows a simplified network topology. All infrastructure devices shown in the exhibit are successfully
implementing (OSPF) on the interfaces. The exhibit also shows settings for OSPF areas. Exhibit 2 shows
additional settings on IRF. The master within IRF 1 fails. Connectivity is disrupted for about one minute.
What can the network administrator do to prevent this issue occurring again?
A.
Set up OSPF Bidirectional Forwarding Detection (BFD) on the routed link aggregation groups between the
IRF virtual switches
B.
Enable extended Link Access Control Detection Data Units (LACPDUs) on IRF 1 and IRF 4
C.
On IRF 1, set up Bidirectional Forwarding Detection (BFD) Multi-Access Detection (MAD) with a dedicated
link.
D.
On each of the IRF virtual switches, enable opaque LSAs and set the OSPF graceful restart mode to IETF
mode.
Explanation:
In a nutshell, the OSPF enhancements for graceful restart are as follows:
– The router attempting a graceful restart originates link-local Opaque-LSAs, herein called Grace-LSAs,
announcing its intention to perform a graceful restart within a specified amount of time or “grace period”.
– During the grace period, its neighbors continue to announce the restarting router in their LSAs as if it were
fully adjacent (i.e., OSPF neighbor state Full), but only if the network topology remains static (i.e., the contents
of the LSAs in the link-state database having LS types 1-5,7 remain unchanged and periodic refreshes are
allowed).
https://tools.ietf.org/html/rfc3623