Juniper Networks IDP250 manual Peer Port Modulation, External Bypass

IDP250 Installation Guide

External Bypass

The External Bypass setting supports third-party external bypass units. When the IDP appliance is turned on and available, it sends NetScreen Redundancy Protocol (NSRP) heartbeats to the external bypass unit. When the NSRP packets flow, the external bypass unit allows connections to proceed through the IDP appliance. If IDP encounters failure or is shut down, it cannot send the NSRP packets. IDP traffic interfaces enter a bypass state. When the external bypass unit detects this, it forwards packets around the IDP appliance, according to the rules you configure on the external bypass unit. See Figure 7 on page 12.

Figure 7: Internal Bypass

When the IDP appliance resumes healthy operations, it resumes sending NSRP packets. The external bypass unit detects this and allows connections to proceed through the virtual router.

Peer Port Modulation

The peer port modulation (PPM) feature supports deployments where routers monitor link state to make routing decisions. In these deployments, a router might be set to monitor link state on only one side of the IDP appliance. Suppose, for example, the router monitors only the IDP inbound interface. Suppose the inbound interface remains up but the outbound interface goes down. The router watching the inbound link would detect an available link and forward traffic to the IDP appliance. Traffic would be dropped at the point of failure—the outbound link. PPM propagates a link loss state for one traffic interface to all interfaces in the IDP virtual router.

12■ Traffic Interface Ports