network [ip] [wildcard]
Enables EIGRP on a network interface by specifying the directly connected network and optional wildcard mask to control which interfaces participate in EIGRP.
network [ip] [wildcard]When to Use This Command
- Enable EIGRP on a LAN segment connected to a router interface, e.g., 192.168.1.0/24.
- Use a wildcard mask to advertise a specific subnet within a larger network, e.g., 10.0.0.0 0.0.0.255.
- Enable EIGRP on a point-to-point WAN link by specifying the exact IP of the serial interface.
- Advertise a loopback interface network for OSPF-like routing stability.
Command Examples
Enable EIGRP on a Class C network
network 192.168.1.0This command enables EIGRP on all interfaces whose IP address falls within the 192.168.1.0/24 network. No wildcard mask is specified, so the default classful mask (255.255.255.0) is used. Any interface with an IP in this range will start sending and receiving EIGRP updates.
Enable EIGRP with a wildcard mask for a specific subnet
network 10.0.0.0 0.0.0.255This command enables EIGRP only on interfaces that have an IP address in the 10.0.0.0/24 range. The wildcard mask 0.0.0.255 matches the last octet exactly. This is useful when you want to advertise a specific subnet within a larger classful network.
Understanding the Output
The 'network' command does not produce direct output. Instead, it configures the router to include the specified network in EIGRP updates. To verify, use 'show ip eigrp interfaces' to see which interfaces are participating, or 'show ip route eigrp' to see learned routes. A correctly configured network will show the interface in the EIGRP neighbor table and the network in the routing table.
CCNA Exam Tips
CCNA exam tip: Remember that the 'network' command uses a wildcard mask, not a subnet mask. The wildcard is the inverse of the subnet mask.
CCNA exam tip: If no wildcard mask is specified, the router assumes the classful mask (e.g., /8 for Class A, /16 for Class B, /24 for Class C).
CCNA exam tip: The 'network' command does not need to match the exact IP of the interface; it matches the network portion. For example, 'network 192.168.1.0' will match any interface with an IP starting with 192.168.1.x.
CCNA exam tip: EIGRP uses the 'network' command to determine which interfaces to enable EIGRP on, not to advertise routes. The actual routes advertised are the networks connected to those interfaces.
Common Mistakes
Mistake 1: Using a subnet mask instead of a wildcard mask (e.g., 255.255.255.0 instead of 0.0.0.255). This will cause the command to be rejected or behave unexpectedly.
Mistake 2: Forgetting to include the 'network' command for all directly connected networks that should be advertised, leading to missing routes.
Mistake 3: Using a wildcard mask that is too broad, enabling EIGRP on unintended interfaces and potentially causing routing loops.
Related Commands
router eigrp [as-number]
Enters EIGRP router configuration mode for a specific autonomous system number, allowing you to configure EIGRP routing protocol parameters.
show ip eigrp interfaces
Displays detailed information about interfaces on which EIGRP is enabled, including neighbor status, pending routes, and interface statistics, used to verify EIGRP adjacency and interface participation.
show ip eigrp neighbors
Displays the neighbor table for EIGRP, showing all directly connected EIGRP routers and their status, used to verify EIGRP adjacencies and troubleshoot neighbor relationships.
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