H3C Technologies H3C S7500E Series Switches - Manual (Page 63)

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Configuring LDP Label Filtering
The LDP label filtering feature provides two mechanisms, label acceptance control for controlling
which labels will be accepted and label advertisement control for controlling which labels will be
advertised. In complicated MPLS network environments, LDP label filtering can be used to control
which LSPs are to be established dynamically and prevent devices from accepting and advertising
excessive label bindings.
Label acceptance control
Label acceptance control is for filtering labels to be accepted, that is, an upstream LSR filters the label
bindings received from the specified downstream LSR and accepts only those permitted by the
specified prefix list. As shown in
Figure 2-8 , upstream device LSR A filters the label bindings received
from downstream device LSR B. Only if the destination address of an FEC matches the specified
prefix list, does LSR A accept the label binding of the FEC from LSR B. LSR A does not filter label
bindings received from downstream device LSR C.
Figure 2-8 Network diagram for label acceptance control
Do
n
ot
filte
r la
bel
bind
ing
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Label advertisement control
Label advertisement control is for filtering labels to be advertised, that is, a downstream LSR
advertises only the label bindings of the specified FECs to the specified upstream LSR. As shown in
Figure 2-9 , downstream device LSR A advertises to upstream device LSR B only label bindings with
FEC destinations permitted by prefix list B, and advertises to upstream device LSR C only label
bindings with FEC destinations permitted by prefix list C.