Service Domain Features
2-4
8000-A2-GB21-30
April 1998
Therefore, when WS1 needs to send a packet to WS2, this is the sequence of
events:
H WS1 sends a packet to Router A.
H Router A invokes ARP to map the WS2’s IP address into a MAC address,
because WS2 appears to Router A to be on the same 135.1 subnet.
H Router B running proxy ARP software receives the broadcast ARP request
from Router A, knows that WS2 is on LAN B, and responds to Router A’s
ARP request with its own MAC address.
H Router A receives the ARP reply, then sends the packet to the MAC address
of Router B.
H Router B then forwards the packet destined for WS2 on LAN B.
NOTE:
The proxy ARP capability is card- or system-dependent and detailed
examples for the MCC card, DSL card, and Hotwire RTU are given in
Chapter 4,
Components of the Network Model
.
Filtering
By default, filtering is disabled on the Hotwire DSLAM system, but you can enable
filtering to selectively filter source or destination packets being routed through the
MCC or DSL cards. Filtering provides security advantages on LANs by restricting
traffic on the network and hosts based on the IP source and/or destination
address.
For more information about filtering, see Chapter 7,
IP Filtering
. For more
information about dynamic IP addressing and the dynamic access control option,
see Chapter 5,
IP Address Allocation
, and the
Hotwire DSLAM for 8540 and 8546
DSL Cards User’s Guide
.
