Viewing the subnet mask on the aggregation switch

You can view the subnet mask on an aggregation switch by using interface-specific commands or checking the Layer 3 VLAN interface configuration. Checking Subnet Masks on InterfacesOn most switches, including Cisco and H3C devices, you can view the subnet mask assigned to an interface using the following methods: Show running configuration for a specific interface: This command displays the IP address and subnet mask configured on the interface. For example, on Cisco devices: CodeCopyshow running-config interface This will show the IP address and subnet mask assigned to that interface.

Show protocols: This command provides a quick overview of all interfaces, their IP addresses, and subnet masks: CodeCopyshow ip interface briefshow protocols While show ip interface brief may not always display the subnet mask, show protocols often includes the prefix length or subnet mask for each interface.

Viewing Subnet Masks in VLAN Aggregation

If your aggregation switch uses VLAN aggregation (super-VLAN and sub-VLANs), multiple VLANs may share a single subnet. In this case: The super-VLAN has a Layer 3 interface with a subnet assigned (e.g., 10. 1.

1. 0/24), which acts as the default gateway for all sub-VLANs. Sub-VLANs do not have independent subnets; they share the subnet of the super-VLAN.

The subnet mask is therefore associated with the super-VLAN interface rather than individual sub-VLANs.

Using IP Subnet Calculators

To understand the subnet mask and host ranges for a given IP address, you can use an IP subnet calculator.

Enter the I

P address and prefix length (CIDR notation) to see: Network addressSubnet maskUsable host rangeBroadcast address This is particularly useful when verifying subnet assignments on aggregated interfaces or planning VLANs.

Summary

Use show running-config interface or show protocols to view subnet masks on aggregation switch interfaces.

For VLA

N aggregation, check the Layer 3 interface of the super-VLAN to determine the subnet mask shared by sub-VLANs. Use an IP subnet calculator to verify subnet details, host ranges, and broadcast addresses. By combining these methods, you can efficiently view and verify subnet masks on aggregation switches and their associated VLANs.