In a fabric comprising two or more nodes, Junos Space provides failover when a node
functioning as the active server (load balancer server or database server) goes down. By
default, Junos Space marks a particular node down and routes failover requests to the
node that Junos Space designates as standby server. Junos Space uses a heartbeat
mechanism to check whether the nodes in the fabric are running. When a node functioning
as the active server fails (the appliance crashes or stops sending heartbeats), the node
functioning as the standby server takes over all resources that were managed by the
node functioning as active server. Nodes in a Junos Space fabric rely on IP multicast
messages to discover each other, therefore ensure that IP multicast packets are reachable
between all nodes.
To add, manage, and monitor the nodes in the fabric, a Junos Space user connects to a
single Web IP address. The IP address of first (active) node and second (standby) node,
and the Web (virtual) IP address must all be in the same subnet. The Web IP needs to
work on both the first and second node in the fabric. When both nodes are in same subnet,
and the first (active) node goes down, the second (standby) node becomes the active
node and packets continue to be directed from the router, to the Junos Space Web IP,
and then to the second node, because both nodes are in same subnet. However, if the
second (standby) node is configured in a different subnet than the first (active) node,
and the first node goes down, the second node becomes the active node, but because
the Web IP now points to the different subnet of the second node, all packets originally
destined for first node won’t be received by the second node.
Virtual Appliance Deployment
The Junos Space Virtual Appliance is stored in the Open Virtualization Format (OVF) 1.0
and is packaged as an *.ovf file, which is a tar file that contains all the files of the Junos
Space Virtual Appliance. OVF is not a bootable format, and you must deploy each Junos
Space Virtual Appliance to a hosted ESX or ESXi server before you can run the Junos
Space Virtual Appliance.
You can deploy a Junos Space Virtual Appliance on a VMware ESX server, version 3.5. or
higher, or ESXi version 4.0 or higher to convert the Junos Space Virtual Appliance to a
virtual machine. After the Junos Space Virtual Appliance is converted to a virtual machine,
you use the VMware vSphere client that is connected to the VMware ESX (or ESXi) Server
to deploy the Junos Space Virtual Appliance on the server.
NOTE: Where the Junos Space Virtual Appliance documentation references
“ESX server” you can use either the ESX server Version 3.5 or later, or ESXi
server, Version 4.0 or later.
Recommendations for Deploying Virtual Appliances on the VMware ESX Server
The CPU, RAM, and disk space provided by the VMware ESX server must meet or exceed
the documented CPU, RAM, and disk space requirements for deploying a Junos Space
Virtual Appliance. In addition, Juniper recommends that, for a multi-node fabric, you
deploy the first and second virtual appliance on separate VMware ESX servers to ensure
failover support.
Copyright © 2010, Juniper Networks, Inc.4
Junos Space Virtual Appliance Installation Guide
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