Introduction to the Hotwire DSLAM
1-16
8000-A2-GB21-30
April 1998
— A different next-hop router is specified for each NSP address domain in
contrast to the routed network case where a single next-hop router was
specified for all NSP domains. If the DSLAM does not know the MAC
address of the NSP premises router, it uses ARP to obtain the MAC
address from the NSP premises router prior to forwarding the packet (i.e.,
the wire center VLAN switch forwards an ARP request over the WAN to
the NSP router).
— Packets flowing from the NSP network to the subscribers are routed to
the subscriber based on the destination IP address of the subscriber as is
most common for IP-routed networks. In this case, the LAN on which the
DSLAM resides appears to be part of a local subnet connected directly to
the NSP premises router. If the NSP router does not know the MAC
address of the subscriber, it uses ARP to obtain the MAC address from
the DSLAM that acts as a proxy for the subscriber. (See the discussion
on proxy ARP in Chapter 2,
Service Domain Features
.)
Understanding the Domain Types
Functionally, the Hotwire DSLAM network model can be divided into:
H Features supporting customers
Features integral to supporting customers are the DSL cards and Hotwire
RTUs.
H Features supporting overall system management
The central point of access for overall system management is the MCC card.
However, the features integral to supporting overall system management are
also distributed throughout the Hotwire DSLAM and the Hotwire RTUs.
To monitor and control the operation of the overall system, the IP addresses of
the Hotwire DSLAM and the Hotwire RTU must be partitioned into two distinct
domains.
H Service domain(s)
The service domain (also known as the NSP domain) resides in a mutually
exclusive domain from that of the management domain. (There should be
one service domain for each NSP served by the Hotwire DSLAM.) One
service domain encompasses an NSP and all of the end-user systems that
subscribe to that NSP.
For more information about the service domain, its features and components,
see Chapter 2,
Service Domain Features
, and Chapter 4,
Components of the
Network Model
.
H Management domain
The management domain resides in a mutually-exclusive domain from that of
the service domains. The NAP provisions IP addresses for the management
domain.
For more information about the management domain, its features and
components, see Chapter 3,
Management Domain Features
, and Chapter 4,
Components of the Network Model
.
For more information about assigning IP addresses, see Chapter 5,
IP Address
Allocation
.
