Novell NETWARE 6, Руководство пользователя

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Understanding
37
Internetwork Packet Exchange
103-000176-001
August 29, 2001
Novell Confidential
Manual 99a
38
July 17, 2001
IPX Address Mapping Gateway
Using the IPX Address Mapping Gateway (IAMG) offers the following three
advantages:
Š Your hosts can connect to a backbone network even when your local
network numbers are not compatible with the backbone addressing
scheme.
Š If the routing protocol in the backbone does not support route aggregation
(such as earlier implementations of NLSP), the routing protocol probably
cannot manage the number of network addresses from every customer.
Even if the routing protocol could handle route aggregation, network
numbers might be assigned in a way that does not lend itself to
aggregation. IAMG enables the summarization of routes in a manner
transparent to the routing protocol by mapping many network numbers to
a single number outside the local network. This capability greatly reduces
the number of networks that must be advertised throughout the global
internetwork.
Š The security of the local intranet is enhanced because local networks are
not advertised throughout the global internetwork.
In Figure 6 on page 38 , any packets generated from the client on the customer
network for the backbone have their source IPX network number converted to
the 01014000 gateway address. In addition to mapping a client network
address to an address compatible with the backbone, IAMG converts the IPX
node address to a unique value based on characteristics of the original node
number. Services on the customer network, such as file servers with Novell
®
Directory Services
®
(NDS
®
) that advertise their network addresses through
SAP and that must be visible in the backbone, are not translated. To be visible
in the backbone network, the services must use a registered backbone address.
All registered source addresses are left untranslated.