A Framework for Integrated Services Over Shared and Switched IEEE 802 LAN Technologies
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Auteur(s) :
A. Smith,
M. Seaman,
A. Ghanwani,
J. Pace,
V. Srinivasan
Classé sous :
Network,
Switches,
Lan,
Parameter,
Local area
RFC 2816 Framework for Int-Serv Over IEEE 802 LAN May 2000
about which BA would be responsible for which segments and bridges
or switches. Further, if a request is made for resource
reservation along the domain of multiple BAs, the BAs must be able
to handle such a scenario correctly. Inter-BA communication will
also be responsible for back-up and recovery in the event of
failure.
6.2. Centralized vs. Distributed Implementations
Example scenarios are provided showing the location of the components
of the bandwidth manager in centralized and fully distributed
implementations. Note that in either case, the RM must be present in
all end stations that need to make reservations. Essentially,
centralized or distributed refers to the implementation of the BA,
the component responsible for resource reservation and admission
control. In the figures below, "App" refers to the application
making use of the BM. It could either be a user application, or a
higher layer protocol process such as RSVP.
+---------+
.-->| BA |<--.
/ +---------+ \
/ .-->| Layer 2 |<--. \
/ / +---------+ \ \
/ / \ \
/ / \ \
+---------+ / / \ \ +---------+
| App |<----- /-/---------------------------\-\----->| App |
+---------+ / / \ \ +---------+
| RM |<----. / \ .--->| RM |
+---------+ / +---------+ +---------+ \ +---------+
| Layer 2 |<------>| Layer 2 |<------>| Layer 2 |<------>| Layer 2 |
+---------+ +---------+ +---------+ +---------+
RSVP Host/ Intermediate Intermediate RSVP Host/
Router Bridge/Switch Bridge/Switch Router
Figure 1: Bandwidth Manager with centralized Bandwidth Allocator
Figure 1 shows a centralized implementation where a single BA is
responsible for admission control decisions for the entire subnet.
Every end station contains a RM. Intermediate bridges and switches in
the network need not have any functions of the BM since they will not
be actively participating in admission control. The RM at the end
station requesting a reservation initiates communication with its BA.
For larger subnets, a single BA may not be able to handle the
reservations for the entire subnet. In that case it would be
necessary to deploy multiple BAs, each managing the resources of a
Ghanwani, et al. Informational [Page 17]