Table of Contents
Advertisement
Introduction to the HotWire DSLAM
1-14
Typically, the NAP network is organized into three components:
— Wire center
The wire center is usually a local serving office where the wiring from the
service subscribers is terminated on the HotWire DSLAM. This could be
a CO.
— Wide Area Network (WAN)
The WAN concentrates and switches data traffic from multiple wire
centers to one or more Regional Centers where service providers have
access to the network.
— Regional center
The NSP's Point-of-Presence (POP) is the access point to the NAP
network for an NSP and is located at the regional center. The connection
from the NAP to the NSP network is typically across a WAN connection
to the NSP router at the regional center. This router acts as a next-hop
location to the NSP's network.
The Network Service Providers (NSPs) can be either public access
providers to the Internet (i.e., Internet Service Providers) or private access
providers to corporate LANs, providing services based on the Internet
Protocol (IP). In some cases, the NSP and the NAP can be a single
organization.
One or more HotWire DSLAMs are connected to a Wide Area Network
Concentrator (WAN-C) via a LAN. The WAN-C concentrates data traffic from one
or more DSLAMs into facilities providing access to the WAN. The WAN-C can be
either a router (a layer 3 networking device) or a VLAN switch (a layer 2
networking device).
If WAN-C is a router, the WAN must be a routed IP network (i.e., a network
of interconnected IP routers).
In this case:
— The router at the wire center is required to support routing policies which
permit packets arriving from the local DSLAMs to be routed based on the
service subscriber source IP address. The packets are routed to the
subscribed service providers' POP based on the source IP address.
— The routing tables in the DSLAM are configured such that the next-hop
router is the IP address of the wire center router for all authorized
subscriber IP source addresses. (See the discussion on source-based
routing in Chapter 6,
In addition, the router at the regional center may need to participate in an
exterior gateway protocol, such as the Border Gateway Protocol, to
exchange routing information between the NSP and NAP routing
networks.
— Packets flowing from the NSP network to the end-user systems are
routed within the NAP network based on the packet destination IP
address.
November 1997
IP Routing
.)
8000-A2-GB21-20
Advertisement
Table of Contents
