Video: Routing issues - Multicast flooding, asymmetrical routing, and missing routes

Vocabulary flashcards covering multicast flooding, asymmetrical routing, and missing routes from the video.

Multicast flooding

Flooding of multicast traffic to all devices in a LAN/VLAN when no host is associated with the multicast MAC in the switch's CAM table; mitigated by blocking unknown multicast packets.

CAM table

Switch Content Addressable Memory mapping MAC addresses to switch ports; used to determine where to forward frames.

Unknown multicast packets blocking

Switch configuration to drop multicast frames addressed to groups with no known receivers to prevent floods.

Asymmetric routing

Traffic for a flow leaves via one path and returns via a different path; problematic for stateful security devices that need visibility of the full flow.

Next hop

The next device a router sends a packet to; differing next hops for forward and return paths can cause asymmetry.

Stateful firewall

A firewall that tracks connection state and requires visibility of all packets in a flow; asymmetry can cause dropped packets.

Deep packet inspection

Security processing that analyzes payloads and requires seeing the full flow; hampered by asymmetric routing.

High availability cluster

Group of redundant routers/firewalls providing failover; load balancing across nodes can introduce asymmetric routing if not designed carefully.

HSRP

Hot Standby Router Protocol; gateway redundancy protocol that can contribute to asymmetry in some load-balanced setups.

Firewall placement

Positioning firewalls closer to protected systems (not at the network edge) to ensure consistent traffic paths and visibility.

Missing routes

A route that is absent from a router's routing table, preventing reachability to a destination.

Static routes

Manually configured routes; typos or misconfigurations can cause routes to be missing.

Show IP Route

Command to display the IPv4 routing table on IOS devices to verify available routes.

Route print

Command to display the system's routing table on Windows hosts to diagnose missing routes.

Dynamic routing protocols

Protocols like OSPF and BGP that automatically exchange routing information; neighbor state issues can prevent convergence.

Neighbor state

The relationship state between two routers in a dynamic routing protocol; incorrect states hinder convergence.

Convergence

The process by which routers running a dynamic routing protocol agree on a consistent network topology and routing tables.

Ping

ICMP echo test used to verify connectivity between two devices.