In the topology shown in Figure 120 on page 541, the two Ethernet ports on PE 1 (2/0 and
3/1) are connected to an 802.3ad-compliant switch, and comprise the set of candidate
ports. Three VLAN subinterfaces are configured on each port. Load-balancing group 100
includes three Martini circuits, one for each pair of subinterfaces on the ports. That is,
three circuits were created: one for the pair 2/0.1 and 3/1.10, one for the pair 2/0.2 and
3/1.20, and one for the pair 2/0.3 and 3/1.30. Each of the three Martini circuits connects
to a remote PE router. The remote PE router receives and sends only a single VC label
for each circuit.
Traffic from the switch can be received on all ports and sent over the appropriate Martini
circuit. For example, traffic from CE 1 to be sent over Martini circuit 1 could arrive on port
2/0 or 3/1 and still be appropriately forwarded.
You configure each circuit for VLAN or S-VLAN subinterfaces that you create across a
set of candidate Ethernet ports. The router distributes traffic from the core through the
candidate ports used by the load-balancing group. If a port is disabled, traffic is
redistributed to a working port.
MPLS Interfaces and Labels
When a layer 2 interface is added to a load-balancing group circuit, an MPLS shim interface
is automatically created on top of that layer 2 interface. The attributes of the shim
interface are inherited from the load-balancing group and cannot be configured.
All MPLS shim interfaces within a load-balancing group circuit point to the same MPLS
next hop. Traffic arriving from the CE router over this set of MPLS shim interfaces is
merged into a single LSP and sent to the remote PE router.
The VC in label for the layer 2 circuit points to a single ECMP MPLS next hop. The legs of
this ECMP next hop are the member shim interfaces of the load-balancing group circuit.
Consequently, ECMP is used to forward traffic arriving from the core across the MPLS
shim interfaces to the CE router.
Configuring Load-Balancing Groups
You configure Martini circuits with load-balancing groups in a separate mode, in which
the member layer 2 subinterfaces are entered one by one. For example, the following
commands configure two Martini circuits to different PE routers, in the same
load-balancing group 100, sharing the candidate Ethernet ports 2/0 and 3/0:
host1(config)#mpls l2transport load-balancing-group 100 mpls-relay 2.2.2.2 202
host1(config-mpls-l2-group)#member interface fast 2/0.500
You can also configure member interfaces as described in the following sections:
•
Adding a Member Interface to a Group Circuit on page 542
•
Removing Member Subinterfaces from a Circuit on page 543
Adding a Member Interface to a Group Circuit
You specify the lower interface as a member interface, as in the following example.
host1(config)#mpls l2transport load-balancing-group 100 mpls-relay 2.2.2.2 202
host1(config-mpls-l2-group)#member interface fast 2/0.500
Copyright © 2010, Juniper Networks, Inc.542
JunosE 11.2.x BGP and MPLS Configuration Guide
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