Side_1_360

The core router is simpler:

• Input interface: LSP label switching, possible
  with hierarchy functionality (push/pop includ-
  ing possible split);


• Output interface: LSP merge (as a conse-
  quence of label switching at the input), moni-
  toring per LSP, CoS or per queue, queueing
  and scheduling.

LSP monitoring in the core router is probably

not necessary, since the bandwidth reservation

for a merged LSP in principle could be based on

the bandwidth reservation for each individual

LSP. A conceptual model of the output interface

is given in Figure 7, presuming again a unique

mapping from LSP to DiffServ queue.

The reservation of resources must in some way

relate to the traffic actually flowing in the net-

work and should therefore be dynamically

changed based on monitoring data as described

above.

The control framework can now be summarised

as follows:

i User traffic is monitored at the router nearest

to the user that is controlled by the operator

and can do parameter control. In what fol-

lows we assume for simplicity that this is the

ingress edge node.

ii The user traffic is mapped to an appropriate

CoS. This can be done as part of i. Based

on CoS and destination edge node the traffic

is mapped to an appropriate LSP. This is

assumed done in the ingress edge node, either

as part of i at the access interface or at the

core interface of the ingress edge node.

iii LSPs are set up between pairs of edge nodes

for carrying user traffic. In core nodes LSPs

carrying the same CoS (L-LSPs) and towards

the same edge node, may be merged to make

the configuration more scalable.

iv The LSPs are set up with reserved bandwidth

using bandwidth parameters negotiated either

using RSVP or LDP. The reserved bandwidth

has implications for configuration of sched-

ulers in the routers. The bandwidth can be re-

configured based on measurements.

Encapsulation

Encapsulation

Encapsulation

Output

link

Flows LSP monitoring Scheduling and

bandwidth

allocation

Mapping of

LSP to queue

Queueing classes

Figure 6 Conceptual model of
the edge router interface to the
core network

LSP merge

LSP merge

LSP merge

Output

link

Scheduling and

bandwidth

allocation

Queueing classes

Figure 7 Conceptual model of
the output interface of a core
router