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JunosE 11.3.x Service Availability Configuration Guide
DSLAM
Subscriber
Broadcast domain in aggregation
170
Virtual Router Redundancy Protocol (VRRP) to detect failures. ICR also enables you to
track the failure of uplink interfaces. ICR currently supports only PPPoE subscribers.
Figure 9 on page 170 illustrates ICR deployment.
Figure 9: ICR Deployment
Service Provider Region
Aggregation
Network
VRRP Multicast path
RADIUS communication
Uplink connectivity to core
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. However, you must keep in mind the
hardware scaling limitations when you configure an ICR cluster containing both E320
routers and ERX routers.
RADIUS
server
Uplink
Active
E Series router
Uplink
Backup
E Series router
Copyright © 2010, Juniper Networks, Inc.
Edge
Core
Active1
Active2
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