gateway
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... details of local connectivity is propagated everywhere, although it
is of little or no use outside the local organization. Especially as
some current gateway implementations do not have much space for
routing tables, it would be good to avoid this problem.
...
... ELSE
send_dg_locally(dg,
gateway_to(ip_net_number(dg.ip_dest)))
...
... ELSE
send_dg_locally(dg,
gateway_to(bitwise_and(dg.ip_dest, my_ip_mask)))
...
...
It may or may not be necessary to modify the "gateway_to"
function, so that it too takes the subnet field bits ...
... host
determines its own address, and how it locates a gateway on its
local network. In all three cases, there are two basic solutions:
...
... facts (e.g., its IP address, the hardware address of a gateway,
the IP address of a domain name ...
... broadcast an "Address Mask Request" message. A
gateway (or a host acting in lieu of a gateway) that receives
...
... gateway (or a host acting in lieu of a gateway) that receives
this message responds with an "Address Mask Reply". If there
...
... host to match the responses it hears against the
request it sent; similarly, there is no problem if more than
one gateway responds. We assume that hosts reboot
infrequently, so the broadcast ...
... All gateways on the local net are (temporarily) down.
...
... succeed. It is possible for a host to recover from a wrong
choice: when a gateway comes up, it should broadcast an "Address
...
... with its guess, it should change its mask to conform to the
received value. No host or gateway should send an "Address Mask
Reply" based on a "guessed" value.
...
... network 36.0.0.0, has address 36.40.0.123, that there is a gateway
at 36.40.0.62, and that a 8-bit wide subnet ...
... Mask: 255.255.0.0
Note that the gateway uses the narrowest possible broadcast to
reply. Even so, the over use of broadcasts ...
... hosts have wired-in
information about neighbor gateways; thus, 36.40.0.123 might send
this datagram:
...
... network 128.99.0.0, has address 128.99.4.123, that there is a
gateway at 128.99.4.62, and that a 6-bit wide subnet field is in
...
... network 192.1.127.0, has address 192.1.127.19, that there is a
gateway at 192.1.127.50, and that on network an 3-bit subnet ...
... Gateway ...