Option: Configuring Layer 2 Circuit Trunk Mode on ATM2 IQ Interfaces
When you configure Layer 2 circuits on CE-facing
ATM2 IQ interfaces in a PE router that connects to some vendors’
ATM switches, you can create a trunk. The trunk bundles several ATM
cell streams into one LSP, preserves the cell loss priority (CLP)
and class-of-service (CoS) information of the cells within the experimental
(EXP) bits of the MPLS header, and provides network-to-network interface
(NNI) or user-to-network interface (UNI) information within a proprietary
header. A physical interface supports a total of 32 logical trunks
in NNI mode and 8 logical trunks when you use the UNI option. To configure
a trunk, include the trunk statement at the [edit
chassis fpc fpc-slot pic pic-slot atm-l2circuit-mode] hierarchy level, select NNI or UNI mode
with the nni or uni statement, and specify a
number of bits in the ATM header that will carry an identifier with
the id-width statement. You can choose a value from 1 through 8 for the identifier width.
[edit]
chassis {
fpc fpc-slot {
pic pic-clot {
atm-l2circuit-mode {
trunk {
(nni | uni) {
id-width number;
}
}
}
}
}
}
You can also configure several trunk options
at the [edit interfaces at-fpc/pic/port unit unit-number] hierarchy level:
To specify an ATM interface as the control channel for a Layer 2 circuit trunk, include the
control-channelstatement at the[edit interfaces at-fpc/pic/port unit unit-number]hierarchy level.To specify a trunk identifier, include the
trunk-idstatement at the[edit interfaces at-fpc/pic/port unit unit-number]hierarchy level. Trunk ID values range from 0 through 31.To configure the amount of bandwidth reserved for the trunk, include the
trunk-bandwidthstatement at the[edit interfaces at-fpc/pic/port unit unit-number]hierarchy level and specify a value from 1,000,000 bps (1 Mbps) through 542,526,792 bps.To apply a CoS scheduler map to the trunk, include the
atm-scheduler-mapstatement at the[edit interfaces at-fpc/pic/port unit unit-number]hierarchy level. This statement must reference an ATM2 IQ interface-based scheduler map at the[edit interfaces at-fpc/pic/port atm-options scheduler-maps map-name]hierarchy level.interfaces { at-fpc/pic/port{ atm-options { pic-type atm2; scheduler-maps {map-name{ ... } } unitunit-number{ atm-scheduler-mapmap-name; control-channel; trunk-idid-number; trunk-bandwidthbandwidth; } } } }
You can configure a variety of CoS-related statements
for an ATM2 IQ interface-based scheduler map. To select the CoS mode
used for virtual circuits, include the vc-cos-mode statement
at the [edit interfaces at-fpc/pic/port atm-options scheduler-maps map-name] hierarchy level. To specify forwarding
class settings, include the priority, transmit-weight, and epd-threshold statements at the [edit interfaces
at-fpc/pic/port atm-options scheduler-maps map-name forwarding-class class-name] hierarchy level.
[edit]
interfaces {
at-fpc/pic/port {
atm-options {
pic-type atm2;
scheduler-maps {
map-name {
vc-cos-mode (alternate | strict);
forwarding-class class-name {
priority (high | low);
transmit-weight (cells number-of-cells | percent percentage);
epd-threshold plp0-threshold plp1 plp1-threshold;
}
}
}
}
}
}