........... 1
2 Translating Logical to Physical Addresses............. 7
2.1 Translation Locus.............. ut having to inform all users of the new physical addresses.
Of course, the reasons these prob... its "logical address" (though in fact, logical
addresses are not addresses at all, since they, like names, are
-4-
IEN-183
IEN #31
On Names, Addresses and Routings (II)
Dan Cohen
ISI
28 April 1978
2.3.3.11 On Names, Addresses and Routings (II)
SUMMARY
This note deals with...
In particular, the notion of extending addresses like
{NET}-[HOST]-(PORT) or {NET}-/I... g cannot be derived in general
from the addresses, it should always either be apriori known,
port on a
particular switch, and hence addresses take the form <switch,
port>. Then rou... vation
for introducing hierarchical addresses, but these two
techniques do not ne...
below. Another reason for hierarchical addresses is simply to
distribute the authority for assigning addresses within a
large system [14].
This hierarchy is easy to manage such that addresses are uniquely
assigned.
Typically in an hierarchy... ations have totally random dependency on their addresses, meaning
that a fully instantiated table looku... aining all the required
information about all the addresses.
In the case of flat addressing it is required that all addresses be
globally unique. It is not required however
his domain, and
begin by asserting that 'names', 'addresses', and 'routes' are different
entities. [Even one ... vailable to
the user that will map names into addresses.
The name (what we seek) need not be bound t... until this mapping takes place; the address (or addresses) associated
with a particular name may change... defines the fundamental
addressable object.
Addresses must, therefore, be meaningful throughout the dom
stinations are hosts identified by
fixed length addresses. The internet protocol also provides for
fragm... net datagram. The TCP module would provide the
addresses and other parameters in the internet header to th...
fragmentation.
The internet modules use the addresses carried in the internet header
to transmit the ... ressing
A distinction is made between names, addresses, and routes [3]. A
name indicates what we s
stinations are hosts identified by
fixed length addresses. The internet protocol also provides for
fragm... net datagram. The TCP module would provide the
addresses and other parameters in the internet header to th...
fragmentation.
The internet modules use the addresses carried in the internet header
to transmit the ... ressing
A distinction is made between names, addresses, and routes [3]. A
name indicates what we s
stinations are hosts identified by
fixed length addresses. The internet protocol also provides for
fragm... net datagram. The TCP module would provide the
addresses and other parameters in the internet header to th...
fragmentation.
The internet modules use the addresses carried in the internet header
to transmit inte... ressing
A distinction is made between names, addresses, and routes [3]. A
name indicates what we s
Section 2.3.3.7
On Names, Addresses and Routings
----------------... eadability.
In addition to names, processes have addresses which indicate WHERE they
are. Again, it is pos...
address, and also that the same name has several addresses.
In order to move messages from sources to dest...
These beautiful definitions of NAMEs (what), ADDRESSes (where) and
ROUTING (how-to-get-there) are borr
the
internal networks are assigned global network addresses and their
interconnecting gateways co-operate in ... e network number. The same host may have several addresses
depending on how many nets it is connected to or ... rk.
For the present, it is assumed that internet addresses have the
form: Net.Host. "Net" is an 8 bit netwo... net gateways maintain tables which allow internet
addresses to be mapped into local net addresses. Local gat
tches. The mapping between names and
(physical) addresses will, in general, be many-many. That is,
one... fer indeterminately to several distinct physical
addresses, either because some one physical machin... nough to assume that
destination network addresses need not themselves be
hierarchical. Ho... ould be responsible for determining the physical
addresses at each level of a never-ending hierarchy. Of c
describes
the mapping between internet local addresses and the actual address
format used in the part... ing transformations are used to convert internet addresses
to local net addresses and vice versa:
ARPANET
-------
The ARPANET (with 96 bit leaders) has 24 bit addresses. The 24
bits are assigned to host, lo
of the gateway. These users are simply the
addresses of the hosts, both on the ARPANET (Catenet) side ... e acceptable as valid source and
destination addresses of packets which transit the gateway. All
other... teway contains a table which maps artificial host addresses
on that network into real 14-digit Telenet/X.25 addresses, in
much the same way as other networks convert
:-
128k |-----------------------|
| I/O addresses |
124k |-----------------------|
... OF window_type;
pct_r0e, pct_r6e : virtual_byte_addresses;
where
TYPE window_type = RECORD par, pdr : INTEGER END;
TYPE virtual_byte_addresses = 0..#177777;
The following field has been remov... pct_r0e and pct_r6e contain the virtual byte addresses of the ends
( smallest numbered address ) of
re common rules for
interpreting internet addresses to perform internet routing.
In transit, da... racteristics. For example, IP
maps internet addresses supplied by ULPs into local addresses
used by the local subnetwork. Also, IP hides any packet-... ation.
A distinction is made between names, addresses, and routes. A
name indicates the objec