Cisco DNCS System Release 2.8 3.8 4.3 Design Guide
4000358 Rev B
Guidelines for Configuring the DBDS for DOCSIS
2-3
IP Address Assignment
Introduction
This section provides guidelines for assigning IP addresses using a carefully-planned
IP addressing scheme and the private IP address space.
IP Addressing Scheme
Because the overall network architecture for each cable service provider can differ,
this chapter describes a simplified view of assigning IP addresses. The cable service
provider must take full control and responsibility of their IP addressing scheme.
Cisco strongly recommends that each cable service provider carefully plan their IP
addressing scheme to allow for any future service growth (such as Cable Telephony
and others). The cable service provider can further divide the IP addresses into
hierarchical subnets. Contact Cisco Services for assistance.
IP network number assignment is guided by classifying each IP host as one of the
following categories:
•
•
Unregistered stand-alone cable modems
•
Registered stand-alone cable modems
•
Registered integrated cable modems
•
DHCT CPE
•
Subscribed PC CPE
Each of the categories above is in the private 10 network space except the subscribed
PC CPE category, which is assigned a public cable service provider/Internet service
provider IP address.
Private IP Address Space
The private IP address space is used for assigning IP addresses to the stand-alone
cable modems, integrated cable modems, and the DHCT CPE.
The private address space will be 10.0.0.0 to 10.255.255.255, which provides
The private address space will be 10.0.0.0 to 10.255.255.255, which provides
16,777,216 IP addresses. Cisco recommends that the cable service provider use a
hierarchical addressing plan whenever possible. A hierarchical addressing plan
allows the cable service providers to efficiently allocate addresses and summarize
their routes in their router equipment. Using this plan also reduces the number of
routing table entries in the routers.
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