21. This Bounds Router Table Size
• There will be Natural Subnets within a layer around the Central Hole.
• Each can be a routing domain; Each Subnet is one hop across the Hole.
– The hole is crossed in the layer below.
• A Topological Space is imposed on the Address Space of Each Layer
Backbone
Regionals
Metros
(N)-Routing
Domains
(N-1)-Routing
Domains
22. Example of Topological Address Assignment
Regionals
Metros
W
N
S
E
•
•
E3920
S4729
Possible Address Space
For Regional Networks
N and S would be similar
Possible Address Space
For Metro Networks
•
ESE8399
W
N
S
E
WW NW SW NE SE EE
•
WWW7428
Note that strictly
speaking the address
spaces are independent
Similarityintheupperpartoftheaddress
hierarchycanbeleveragedtosimplifyrouter
calculations.
28. Why Can WiFi Have 4 MAC Addresses?
BSS-
id
Laptop Access
Point
Router/
Cable Modem
Sndr/Rcvr
“Ethernet” btwn SRC/DEST
IP
Laptop Access
Point
Access
Point
Router/
Cable Modem
Sndr/Rcvr Sndr/Rcvr
“Ethernet” btwn SRC/DEST
IP
• Because it is really two layers!
• In general, there is forwarding across access points. First two addresses would be
SNDR/RCVR addresses and would change at every hop, while . . .
• Over the top is a logical Ethernet with Src/Dest addresses constant, continuous
with the Wired Ethernet connecting the last Access Point to the Router.
• The most common configuration is a Star Network connected to a Router/Cable
Modem. In this case, the SRC and SNDR addresses are the same, so only 3 addresses
are necessary.
• VLANs are doing the same thing: Multiple Layers of the Same Rank over a Common Media
29. WiLAN Model
• The Wired Media DIF is point-to-point between a station or bridge and
another bridge.
– Hence, this DIF does not need addresses, but does need CEP-ids and
port-ids.
• OTOH, the wireless-media DIF is also point-to-point but needs both
addresses and CEP-ids.
– Because multiple wireless networks may exist in the same physical
space.
• Over the top is any ordinary DIF.
Station
Bridges
Access
Point
Wired Media DIFs
Wireless Media DIF
Station
36. How It Works
• There is a repeating structure of name mappings.
• The DIF Allocator has an NSM of Application-Names with scope greater than any one DIF. Associated with each name is the
name of the processing system on which it resides, and a list of supporting DIFs. From this information, the DA is able to
project the application-names into the Flow Allocator of supporting DIFs and the IPC Processes of that DIF.
• The Flow Allocator keeps the mapping of each application-name to the synonym of the IPC Process in the same processing
system.
• The Resource Allocator contains an NSM for the synonyms for each IPC Process, i.e. addresses, in this DIF and the (N-1)-
DIFs supporting the synonym. The Resource Allocator is consulted during Enrollment to get appropriate synonyms assigned.
The Resource Allocator also injects information for the (N-1)-Flow Allocator, serving the analogous service as the DIF
Allocator.
• Needless to say, that this mapping information may be acquired from bottom up as well as top down.
• Supporting DIF-name and access control information might only be stored “near” the object named for security reasons, to
keep databases small, or accommodate frequent changes.
• There may be a topological relation between synonym spaces of (N)- and (N-1)-DIFs.
• It is highly unlikely that there will be a topological relation between the Application Name Space and the Synonyms of a DIF.
– A topological relation between Name Spaces of DAFs is a different matter.
DIF Allocator
Flow Alloc
Res-Alloc
DA-NSM: Application-names - DIF/DAF names, Processing Systems
FA: (N+1)-names - (N)-names
RA: (N)-names-
(N-1)-names,
(N-1)-DIFs