The purpose of this article is to present use cases and feature configuration details for various LAN related situations:
Generally it is not necessary to change the LAN side default IP address and subnet but there may be situations where it is necessary. One example of when it is necessary to change the default LAN IP address and subnet is when the gateway is being added to an existing LAN with Static IP addresses assigned to devices on the LAN and it is not practical or possible to change those IP addresses.
A subscriber with an IP based security system has switched internet service providers. The system has static addresses that were assigned to run on the 10.0.0.0/24 subnet with a default gateway of 10.0.0.254. To change the IP addresses on the security system, would require potential down time, a service call from the security company and possibly additional expense for the subscriber. It may be in the best interest for the new service provider to be accommodate a work-around at the gateway by changing the subnet and default gateway on the SmartRG modem.
To change the default subnet and gateway, complete the following steps:
To access these settings, select Advanced Settings -> LAN from the left navigation bar.Enable IGMP Snooping:
When enabled, the gateway will listen to multicast control traffic passing through the router that is destined to or from a source and destination address. Based upon the conversation that the gateway hears, it builds a map of which hosts on the LAN side of the router requested the traffic.By default, when a switch receives a multicast frame, it floods it out every port. Enabling IGMP Snooping prevents this default flooding behavior.
A home network with one laptop and one set top box connected to the LAN. The laptop has no need to receive the multicast video stream intended for the set top box. Without IGMP Snooping enabled, the laptop will need to process and drop every multicast video frame which could cause performance degradation.
Generally it is not necessary to change the LAN side default DHCP Subnet pool size, range or lease duration. When a block of IP addresses are set aside for special use is one example of when it is necessary to alter that default range.
The first fifty addresses of the 10.0.0.0/24 subnet were allocated to the home owners’ security system which includes a controller, door and window sensors, as well as security cameras that all require static IP address assignments. Note that DHCP could have been used for the security related devices in conjunction with Static IP Lease List if there were 32 or less addresses required, however, since the requirement was fifty, the DHCP pool size must be adjusted accordingly. For non-security related appliances, the rest of the /24 block can be utilized for DHCP. The DHCP range for this example should be modified such that 10.0.0.51 is the start address and 10.0.0.253 is the end address. Note that 10.0.0.254 was excluded because that address is the new default gateway, i.e. the LAN side modem address.
Generally it is not necessary to have more than one DHCP Subnet pool on a modem but there may be corner cases where it is necessary. One example of when it is necessary to create a second DHCP Subnet pool is when traffic must be kept separate.
A homeowner has an IP based security system with several static addresses that were assigned to run on the 10.0.0.0/24 subnet with a default gateway of 10.0.0.254. The home owner has changed to a new internet service provider but wants to keep this network separate from the home network but also needs this network to connect to the internet.The gateway could be setup where the family and guests could use the 192.168.1.0/24 subnet which would be assigned to all wireless clients and 10.0.0.0/24 assigned to any wired device. To setup multiple DHCP Pools, complete the following steps: