14.2: Packet Forwarding

Question 1

Now that the router has determined the best path for a packet based on the longest match, it must determine how to ___ the packet and ___ it out the correct egress interface.

Answer 1

encapsulate
forward

Question 2

The following steps describe the packet forwarding process:

____The data link frame with an encapsulated IP packet arrives on the ingress interface.
____The router encapsulates the packet in a data link frame and forwards it out the egress interface. The destination could be a device connected to the network or a next-hop router.
____The router finds the longest matching prefix in the routing table.
____However, if there is no matching route entry the packet is dropped.
____The router examines the destination IP address in the packet header and consults its IP routing table.

Answer 2

The following steps describe the packet forwarding process:

1. The data link frame with an encapsulated IP packet arrives on the ingress interface.
2. The router examines the destination IP address in the packet header and consults its IP routing table.
3. The router finds the longest matching prefix in the routing table.
4. The router encapsulates the packet in a data link frame and forwards it out the egress interface. The destination could be a device connected to the network or a next-hop router.
5. However, if there is no matching route entry the packet is dropped.

Question 3

Forwards the Packet to a Device on a Directly Connected Network
If the route entry indicates that the egress interface is a ____ network, this means that the destination IP address of the packet belongs to a device on the directly connected network. Therefore, the packet can be ___ to the destination device

Answer 3

directly connected
forwarded directly

Question 4

Forwards the Packet to a Device on a Directly Connected Network
The destination device is typically an end device on an Ethernet LAN, which means the packet must be encapsulated in an ___.

Answer 4

Ethernet frame

Question 5

Forwards the Packet to a Device on a Directly Connected Network

To encapsulate the packet in the Ethernet frame, the router needs to determine the ____ MAC address associated with the ***IP address of the packet.

Answer 5

destination

Question 6

Forwards the Packet to a Device on a Directly Connected Network
Encapsulation process varies based on whether the packet is an IPv4 or IPv6 packet:

__: The router checks its __ table for the destination IPv4 address and an associated Ethernet ___ address. If there is no match, the router sends an ARP Request. The destination device will return an ARP Reply with its MAC address. The router can now forward the IPv4 packet in an Ethernet frame with the proper destination MAC address.

Answer 6

IPv4 packet
ARP
MAC

Question 7

Forwards the Packet to a Device on a Directly Connected Network
Encapsulation process varies based on whether the packet is an IPv4 or IPv6 packet:

___: The router checks its ___ for the destination IPv6 address and an associated Ethernet MAC address. If there is no match, the router sends an ICMPv6 ___message. The destination device will return an ICMPv6 ____ message with its MAC address. The router can now forward the IPv6 packet in an Ethernet frame with the proper destination MAC address.

Answer 7

IPv6 packet
neighbor cache
Neighbor Solicitation (NS)
Neighbor Advertisement (NA)

Question 8

Forwards the Packet to a Next-Hop Router

If the route entry indicates that the destination IP address is on a ___, this means the destination IP address of the packet belongs to a device on network that is not directly connected.

Answer 8

remote network

Question 9

Forwards the Packet to a Next-Hop Router

Therefore, the packet must be forwarded to another router, specifically a next-hop router. The next-hop address is indicated in the ____.

Answer 9

route entry