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JUNOSe 11.1.x Service Availability Configuration Guide
also enables you to track the failure of uplink interfaces. ICR currently supports only
PPPoE subscribers.
Figure 7 on page 128 illustrates ICR deployment.
Figure 7: ICR Deployment
DSLAM
Subscriber
Broadcast domain in aggregation
The subscriber broadcasts a PPPoE Active Discovery Initiation (PADI) packet to both
the master and backup router. Only the master router processes the packet and creates
the subscriber session. When the master router fails, VRRP switchover occurs and
the backup router becomes the new master router. When receiving traffic for
non-existent PPPoE sessions, the new master router sends early termination requests
by sending PPPoE Active Discovery Termination (PADT) packets to the clients instead
of waiting for the client to reconnect after the PPPoE session expires. The clients
respond by sending requests to log in again. Then, the new master router creates
new sessions for the PPPoE subscribers.
In lower-numbered releases, the new master router dropped the PPPoE packets
because a session did not exist for the PPPoE subscribers and did not send PADT
packets.
ICR achieves load balancing in case of failures on a per physical port basis by enabling
you to create partitions. An ICR partition is a set of S-VLANs (and CVLANs) associated
with a unique VRRP instance. There can be multiple partitions per physical port. A
partition is the basic unit of redundancy. A partition cannot span multiple physical
ports.
You can also create ICR clusters. An ICR cluster consists of a group of routers
participating in ICR. You can use different E Series routers to configure a
heterogeneous ICR cluster. For example, you can use an E120 or E320 router with
an ES2 4G LM as a backup for subscribers on an ERX1440 router, or use an ERX1440
router with a GE-HDE LM as a backup for subscribers on an E120 or E320 router.
128
ICR Overview
Service Provider Region
Aggregation
Network
VRRP Multicast path
RADIUS communication
Uplink connectivity to core
RADIUS
server
Uplink
Active
E Series router
Uplink
Backup
E Series router
Edge
Core
Active1
Active2
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