IP Address Allocation and Route Planning for the NGN bearer network

The NGN Service has an end-to-Peer () and permanent online Always-on-Line () communication mode. A large number of IP addresses need to be allocated, resulting in insufficient public IP addresses. At the same time, carriers must use technologies such as static routing, dynamic routing, Policy Routing, and routing policies in the Metropolitan Area Network to set up metro routes to ensure that users' services are connected to the corresponding service network.

I. IP Address Allocation
IP address range

The NGN service is isolated from the data service layer 2 in the Metropolitan Area Network. The NGN Service Network is an independent logical network that can independently plan IP addresses, adopt private IP addresses, or use public IP addresses, public IP addresses can also be used for private purposes. The advantage of private public network address is that the number of addresses is large, theoretically 4 billion addresses, convenient planning and expansion, but with other public network intercommunication need IP-IP Intercommunication Gateway.

Address Allocation Method

Core devices of the NGN service network can be allocated static IP addresses, for example, compared with switches, TMG, AG, and servers, A large number of corridor IAD, SIP smart terminals, and PCs are connected to the NGN service network and data service network through the BAS device at the Metropolitan aggregation layer. BAS authenticate the connected devices and assign IP addresses. BAS should assign the NGN service network IP address to the IAD and the data service network IP address to the PC. The two IP address pools cannot overlap.

From the operator's operational and manageable perspective, the iad ip address can be dynamically allocated through DHCP. BAS supports built-in dhcp sever or dhcp relay. Through dhcp relay, BAS can assign IP addresses to IAD or PC from the centralized DHCP server, which is more in line with the idea of centralized IP address management by operators.

Role of BAS in IP Address Allocation

In the metro access layer, the NGN Service and Data Service are isolated through the L2 VLAN, and then mapped to the mpls vpn of the metro backbone layer through the PE device. If IAD and PE are completely layer-2 devices, then a large number of IAD VLANs will end on PE. On the one hand, PE supports a limited number of VLANs (VLAN <4096 ), on the other hand, each VLAN requires an IP address segment, so that DHCP has many scopes, address blocks are broken, and address waste is serious. Each IAD occupies at least four IP addresses. If the BAS device is added between IAD and PE, you can use the built-in DHCP Server or DHCP Relay function to identify different services and assign different IP address Domains Based on VLAN, after Service aggregation, the service is distributed to the corresponding uplink physical interface and VLAN sub-interface, and then the PE device is connected, so that the PE can map the NGN business flow to the corresponding mpls vpn of the NGN business network. The Super Vlan Technology on BAS can solve the problem of broken address blocks when VLAN is isolated from users. VLAN users in the same IP segment can use arp proxy to solve interconnection problems. This method avoids the direct termination of a large number of IAD VLANs on the PE and saves a lot of IP addresses. If BAS supports PE, you can also directly map the NGN service to the mpls vpn of the man.

Ii. Route Planning
The BAS device assigns an IP address to the IAD, so the IAD route is a direct route on the BAS. The BAS at the city aggregation layer not only authenticates the connected IAD, but also assigns an IP address. It also authenticates the connected pc and assigns an IP address. Through authentication, BAS can identify the business attributes of the access device. Through policy routing, different services can be distributed to different uplink physical ports or VLAN subinterfaces, access the corresponding service network through PE. For downstream streams, PE routes downstream streams to BAS through static routes. BAS routes downstream streams to the corresponding user ports based on the direct routes.

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