Router Packet Forwarding and Static Routes ccna 2

Router Packet Forwarding

• Router R1 will forward a packet with a destination IPv6 address of 2001:db8:cafe:5::1 out GigabitEthernet0/0 if a route for that address is found in its routing table.
• If no specific route is found, the default route is used.

Floating Static Route

• A floating static route has an administrative distance greater than the active route in the routing table to act as a backup.
• The administrative distance of the active EIGRP route to the 10.10.0.0/16 network is 90.
• The floating static route needs to have a higher administrative distance than the active route to be activated when there is a link failure.
• The next hop address should also match the corresponding serial interface IP address of the backup device.

Incorrect Static Route

• A static route configured with the wrong destination network and mask will prevent users on the 172.16.0.0/16 network from accessing the internet.
• The correct destination mask should be 0.0.0.0 when making a default static route for the LAN to internet connectivity.

IPv4 Default Static Route

• The correct IPv4 default static route format is: ip route 0.0.0.0 0.0.0.0 .
• Using the correct exit interface is vital for the route to be functional.

Static Route for Forwarding Traffic to a LAN

• A static route command will be issued on R1 to redirect traffic to the LAN connected to R2.
• The destination network and its mask need to be defined.

IPv6 Static Route Command

• The ipv6 route command is used for configuring IPv6 static routes.
• The appropriate format should be provided to correctly define the route.

VLAN Hopping Attack

• A method to launch a VLAN hopping attack involves introducing a rogue switch and enabling trunking.
• Sending spoofed native VLAN information or flooding the switch with MAC addresses are also methods to launch a VLAN hopping attack.

DHCPv6 Server Configuration

• A router configured as a DHCPv6 server that doesn't have any active clients will show a client count of 0.
• This is because the clients will configure their IPv6 addresses by using the link-local address of the router interface as the default gateway.

HSRP Group Configuration

• In HSRP group 1 configuration, users on Host1 will experience connectivity issues to the Internet after reloading routers R1 and R2.
• The ARP table on Host1 will contain an entry for the virtual IP address of HSRP group 1 and the MAC address of the router that is currently active in the group.

Frame Forwarding Decisions

• Layer 2 switches make frame forwarding decisions based on MAC addresses and port mappings in the content addressable memory (CAM) table.
• Frames with broadcast destinations are forwarded to all active ports.

VLANs and Interconnected Switches

• Interconnected Cisco LAN switches form a single broadcast domain.
• Each switch port represents a separate collision domain.

Link State and Protocol Status

• A link can be up/up, down/down, administratively down or disabled.
• Protocol status is determined by the state of the related interface.

MAC Address Table on Empty Switch

• If the MAC address table is empty, the switch will flood the frame to all ports, except the originating port, in order to reach the destination device.

VLANs Not Removed

• Default VLANs (VLANs 1-1005 or similar standard ranges) are stored in a file (e.g., vlan.dat) on the switch's flash memory.
• Deleting VLANs requires deleting the file and reloading the switch.

Removing VLANs from a Cisco Switch

• Default VLANs(VLAN 1-1000) cannot be removed by simply removing the configuration.
• They need to be manually deleted.

Secure Remote Access Configuration

• Configuration options for remote network device access include enabling 802.1X, SSH and ACLs in VTY lines.
• For remote access, using SSH is the most secure.

Wireless Encryption Methods

• WPA2 with AES is considered the most secure wireless encryption method.

Accessing Internet with Static Route

• An incorrect static route (e.g,, incorrect destination network and mask) can prevent access to the internet.
• The correct destination network and mask are needed to reach resources on the internet.

Static Route to Forward Traffic

• Static routes are manually configured network routes that are used to direct traffic between networks. A static route to a LAN connected to R2 would need to include the IP address of that network.

Static vs Dynamic Routes

• Static routes are manually configured routes and are less susceptible to network topology changes.
• Dynamic routes adapt to changes in the network topology automatically.

Router Security via Static Routes

• Static routes can be used to improve network security by limiting network routes.
• They do not adapt to topology changes as compared to dynamic routes.

Layer 2 Switch Forwarding

• Switches forward frames based on the MAC address of the destination.
• If the destination MAC address is not in the CAM, the switch floods the frame to all ports except the incoming port.
• Specific configurations ensure correct traffic delivery across all ports.

Static Route to a Specific Network

• A static route with a specific destination network and next-hop address is used for directing traffic.
• If configured improperly, the traffic might not reach the target network.

Spanning-Tree Protocol (STP) Configuration

• STP is used to prevent loops in a switched network, which would prevent access to specific networks.
• On some switches the portfast configuration command directly disables STP and thus prevents loops on specific ports.

IPv6 Link-Local Address

• The IPv6 prefix for link-local addresses is FE80::/10.

Routed Ports on Multilayer Switches

• Routed ports connect to a router's interface.
• Typically found in core or distribution layers.
• Provide connectivity between different VLANs.

VLAN Configuration on Switches

• A VLAN configuration includes a VLAN ID and the ports allocated to that ID.
• Different VLANs are typically used for different devices or functions.

Removing VLANs

• If a switch has VLANs that should be deleted, remove them in a proper manner—the VLAN dat file needs to be manually removed from the flash memory. Any configuration files need to be updated in the configuration file so that the switch can then be reloaded with the updated configuration.

VTP Configuration

• VTP mode determines how VLANs are communicated across a network.
• Two modes allow for modification and deletion of VLANs on a local switch: master and client mode.