Thursday, May 8, 2008

UDP Broadcast Relay : TR-069 Support

UDP broadcast relay functionality became very popular due to NetBIOS. Broadcast packets are used by NetBIOS for name resolution. Windows Network neighborhood is one functionality that makes use of NetBIOS name service. Due to broadcast functionality, NetBIOS name service works within subnet. If there are multiple subnets, then WINS Server is required. Broadcast relay functionality in routers separating subnets eliminates the need for WINS Servers. Name resolution using UDP broadcast relay function can even be extended to networks in remote offices by relaying broadcast packets over VPN tunnels.

UDP broadcast relay functionality in routers receives broadcast packets and send to other subnets by replacing destination IP of original packet with destination subnet broadcast address.

Since firewall/VPN gateways are also routers, this functionality is implemented in many firewall/VPN gateways. These gateways provide control for administrators on type of broadcast packets to relay and destination subnets to relay to. Multiple of these rules can be created for different types of broadcast addresses.

Configuration consists of set of rules. Each rule containing incoming braodcast IP address/interface and relay subnets/interfaces. Rules can be created and deleted by administrator.

TR-069 profile:
  •{i}.UDPBroadcastRelay.{i} PC
    • name: String(32), RW, Mandatory - Identification of broadcast relay rule. Once rule is created, this value can't be changed.
    • description: String(128), RW, Optional
    • enable: Boolean, RW, Mandatory: Value 1 indicates the record is enabled and 0 is used to disable.
    • incomingBroadcastAddressType: String(16), RW, Mandatory - Indicates whether the broadcast address is represented as an IP address or Interface identifier. Takes one of the values "ipaddress", "interface".
    • incomingbroadcastAddress: String(128), RW, Mandatory - Either dotted IP address or Fully qualified TR-069 instance of VLAN, LANDevice, WANPPPConnection or WANIPConnection etc.
    • incomingbroadcastPort: Integer, RW, Mandatory - Destination Port of incoming broadcast packet.
    •{i}.UDPBroadcastRelay.{i}.relayTo.{i} PC
      • relayBroadcastAddressType: String(16), RW, Mandatory - Indiacates whether the relayTo broadcast address is specified as IP address or interface - Takes one of the values "ipaddress", "interafce".
      • relayBroadcastAddress: String(128), RW, Mandatory - Either dotted IP address or fully qualified instance of interafaces from VLAN, LANDevice, WANPPPConnection or WANIPConnection.
In case of remote subnets, relayBroadcast is specified as remote subnet broadcast IP address. If the subnets are directly attached to the router, then interface names can be used in relayBroadcastAddress field.

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