PrepAway - Latest Free Exam Questions & Answers

Which method of Layer 3 switching uses a forwarding information base (FIB)?

Which method of Layer 3 switching uses a forwarding information base (FIB)?

PrepAway - Latest Free Exam Questions & Answers

A.
Topology-based switching

B.
Demand-based switching

C.
Route caching

D.
Flow-based switching

E.
None of the other alternatives apply

Explanation:
The Layer 3 engine (essentially a router) maintains routing information, whether from static
routes or dynamic routing protocols. Basically, the routing table is reformatted into an
ordered list with the most specific route first, for each IP destination subnet in the table. The
new format is called a Forwarding Information Base (FIB) and contains routing or forwarding
information that the network prefix can reference.
In other words, a route to 10.1.0.0/16 might be contained in the FIB, along with routes to
10.1.1.0/24 and 10.1.1.128/25, if those exist. Notice that these examples are increasingly
more specific subnets. In the FIB, these would be ordered with the most specific, or longest
match, first, followed by less specific subnets. When the switch receives a packet, it can
easily examine the destination address and find the longest match entry in the FIB. The FIB
also contains the next-hop address for each entry. When a longest match entry is found in
the FIB, the Layer 3 next-hop address is found, too.

6 Comments on “Which method of Layer 3 switching uses a forwarding information base (FIB)?”

  4. sdasd says:

    This answer is D not A

    NEW QUESTION 5
    Which statement about HSRP, GLBP, and VRRP is true?

    A. VRRP group members communicate using multicast address 224.0.0.102.
    B. MAC address 0000.0c07.acOc indicates that default gateway redundancy is provided through GLBP.
    C. HSRP group members communicate using multicast address 224.0.0.18.
    D. GLBP uses UDP port 3222 (source and destination) for hello messages.

    Answer: D




    0



    0

Leave a Reply