JUNOSe 9.1.x System Basics Configuration Guide > Managing High Availability > Application Support

Application Support

Applications are either supported or unsupported by high availability.

• Supported—You can configure supported applications without having any adverse impact to high availability. When a switchover occurs, supported applications can react to switchovers in one of two different ways:

• Gracefully recover using mirrored static and dynamic information (for example, IP, PPP, and PPPoE)
• Recover using static configuration only; that is, no runtime state is restored after a switchover. Dynamic configuration and state information are lost. (For example, CLI sessions are restarted, telnet sessions are dropped, multicast routes must be rebuilt, and so on.)

• Unsupported—We recommend that you not configure unsupported applications on a chassis running in high availability mode. Although configured unsupported applications suspend high availability or prevent high availability from becoming active, they do not cause any problems with the function of the router.

Table 45 indicates which applications support or do not support stateful SRP switchover.

 Table 45:  Application Support for Stateful SRP Switchover 

 Application
 Supported
 Unsupported
 Notes

 Physical Layer Protocols
 

 

 


 DS1 


 –

 –


 DS3 


 –

 –


 HDLC 


 –

 –


 SONET/SDH 


 –

 –


 SONET/SDH VT 


 –

 –


 Link-Layer Protocols
 

 

 


 ATM 


 –

 Static and dynamic interfaces, with the exception of ATM subscribers, are supported.
 In this case, ATM subscribers refers to a technology on the E-series router where the ATM layer does authentication (that is, not PPP or IP subscriber manager).


 ATM 1483 bulk configuration of dynamic interfaces


 –

 –


 Bridged Ethernet 


 –

 –


 Cisco HDLC 


 –

 –


 Ethernet (with and without VLANs) 


 –

 –


 Frame Relay 


 –

 –


 PPP 


 –

 –


 PPPoE 


 –

 –


 Transparent bridging 


 –

 –


 Unicast Routing
 

 

 


 Access Routes


 –

 –


 BGP


 –

 Supported only when the graceful restart extension is enabled.


 FTP


 –

 Static recovery support only.


 IP


 –

 –


 IPv6

 –


 –


 IPSec Transport 

 –


 –


 IPSec Tunnels 


 –

 Completed IKE phase 1 and phase 2 negotiations supported only.


 IS-IS


 –

 Supported only when the graceful restart extension is enabled.


 OSPF


 –

 Supported only when the graceful restart extension is enabled.


 RIP


 –

 Static recovery support only.


 Static Routes


 –

 –


 Telnet


 –

 Static recovery support only.


 IPv4 Multicast Routing
 

 

 


 Multicast Routing


 –

 Static recovery support only. During switchover, the system mirrors the multicast queue so that IP can use the same queue without needing to recreate a different connection.


 DVMRP


 –

 Static recovery support only. DVMRP gives the restart complete indication to the IP routing table after getting a peer update (60-second time-out).


 IGMP


 –

 IC IGMP deletes its interface and membership state on SRP failover (controller down). As part of SRP warm start, IGMP interfaces are reconfigured from NVS and dynamic IGMP interfaces are reconfigured from mirrored storage. IGMP hosts are queried as IP interfaces come back up, the join state is re-established, and SC IGMP state is created. After the maximum query response time (across all interfaces) expires to allow hosts to re-establish join state, IGMP notifies MGTM that graceful restart is complete.


 PIM


 –

 Static recovery support only. For warm start, PIM interfaces are reconfigured from NVS and a Hello message with a new Generation ID is issued as IP interfaces come up. A neighbor that receives this Hello determines that the upstream neighbor has lost state and needs to be refreshed. A VR-global configurable graceful restart timer is required for PIM to time out the re-establishment of the join state for sparse-mode interfaces. After this timer expires, PIM notifies MGTM that graceful restart is complete. 


 IPv6 Multicast Routing
 

 

 No multicast routing state information remains following a switchover. Incremental support for multicast routing is planned for future releases.


 Multicast Routing

 –


 –


 MLD

 –


 –


 PIM

 –


 –


 Multiprotocol Label Switching
 

 

 


 MPLS


 –

 MPLS is HA-unsafe during a graceful restart. It is HA-unsafe until all the configured MPLS signaling protocols have completed their graceful restart procedures and any stale forwarding elements have been flushed from the line modules.
 If you force an SRP switchover while MPLS is HA-unsafe, the SRP module switches but the SRP module and the line modules undergo a cold restart.
 If the primary SRP module resets while MPLS is HA-unsafe, the router undergoes a cold restart.


 BGP signaling


 –

 


 LDP signaling


 –

 To provide uninterrupted service during an SRP switchover in a scaled configuration, such as one with 32,000 Martini circuits, set the LDP graceful restart reconnect time to the maximum 300 seconds and set the LDP graceful restart recovery timer to the maximum 600 seconds. This requirement is true for all SRP switchovers, including those in the context of a unified in-service software upgrade.


 RSVP signaling


 –

 


 Local cross-connects between layer 2 interfaces using MPLS 


 –

 –


 Policies and QoS
 

 

 


 Policies


 –

 –


 QoS 


 –

 Static recovery support only.


 Remote Access
 

 

 


 AAA 


 –

 –


 DHCP External Server and Packet Trigger


 –

 Following a switchover, the DHCP lease (that is, time remaining) is recalculated based on when the lease started. When the release timer for a client expires, the client is deleted and the access route is removed, along with the dynamic subscriber interface if it was created. If the client requests a new lease, DHCP external server resynchronizes with the new lease time.


 DHCP Packet Capture


 –

 –


 DHCP Proxy Client 

 –


 –


 DHCP Relay Proxy

 –


 –


 DHCP Relay Server


 –

 Before HA support, clients identified by the DHCP relay server were maintained on a switchover (their state was stored to NVS); DHCP relay server always had some level of HA support. 
 Currently, following a switchover, the DHCP lease (that is, time remaining) is reset. When the release timer for a client expires, the client requests a new lease. The E-series router DHCP relay server then synchronizes with the new state.


 DHCPv4 Local Server


 –

 –


 DHCPv6 Local Server

 –


 HA does not support IPv6.


 L2TP 


 –

 


 L2TP Dialout 

 –


 –


 Local Address Pools


 –

 The internal local address server state supports only static recovery. However, the AAA application reallocates active addresses on a switchover. The resulting effect is the local address server having full HA support.


 RADIUS Client


 –

 Similar to local address server, AAA recovers disrupted RADIUS communication on a switchover. The resulting effect is the RADIUS client having full HA support.


 RADIUS Dynamic-Request Server 


 –

 Static recovery support only.


 RADIUS Initiated Disconnect

 a


 –


 RADIUS Relay Server


 –

 –


 RADIUS Route-Download Server


 –

 –


 SRC Client


 –

 –


 TACACS+


 –

 Static recovery support only.


 Miscellaneous
 

 

 


 Firewall


 –

 –


 J-Flow (IP flow statistics)


 –

 –


 Line Module Redundancy


 –

 –


 Network Address Translation


 –

 –


 NTP


 –

 –


 Resource Threshold Monitor


 –

 –


 Response Time Reporter


 –

 –


 Route Policy


 –

 Static recovery support only.


 Subscriber Interfaces


 –

 –


 Tunnels (GRE and DVMRP)


 –

 –


 VRRP


 –

 Static recovery support only.



 

 CAUTION: When IP tunnels are configured on an HA-enabled router and the Service Module (SM) carrying these tunnels is reloaded, HA transitions to the pending state. HA remains in the pending state for 5 minutes after the successful reloading of the SM. This amount of time allows for IP tunnel relocation and for the tunnels to become operational again on the SM. If an SRP switchover occurs while HA is in the pending state, the router performs a cold restart.