# Index

A B C D E F H I L M N P Q R S T U V W

A

> access modules
>   ES2 4G LMs as
>     in an LNS device, stateful switchover
> access modules in the LNS
>   receipt of event from an application
>     access module processes PPP echo requests
>     failure with the primary module
> Access-Request messages
>   ICR Partition ID VSA
> Acct-Start messages
>   ICR Partition ID VSA
> Acct-Stop messages
>   ICR Partition ID VSA
> activating guidelines
>   high availability, line modules
>     mirroring configuration files from active to standby
>     reverting to default redundancy mode
>     same software release on primary and secondary modules
> active
>   high availability state
> active, line module high availability state
>   change in previously matching criterion
>     transition to disabled state
>   mirroring of information
>     relevant applications create and post transactions
>     standby module replays updates and performs changes for applications
>     updates in settings sent to standby module
>   synchronization of data
>     from active to standby module
>   unsupported application configured
>     transition to disabled state
>   when a switchover occurs
>     warm restart of standby module
> application support
>   high availability
> Automatic Reversion
>   enabling
> automatic switchover
>   limitations
> Automatic Switchover
>   disabling

B

> backup router
>   defined
>   election process and 1, 2
>   VRRP

C

> call setup rate
>   data synchronization
>     impact on
>   under peak load conditions
>     time for system to become HA-active
> clear redundancy commands
>   clear redundancy history
> cold boot
>   of secondary line module
>     when slot is disabled
>     when slot is reloaded
>     when software fault occurs
> commands for configuring
>   stateful SRP switchover
>     similarity with commands for stateful line module switchover
> connection manager
>   usage of stream ID
>     to identify connections
> conventions
>   notice icons
>   text and syntax
> customer support
>   contacting JTAC

D

> data synchronization
>   call setup rate impact
>     consumption of backplane bandwidth
> deactivating
>   high availability, line modules
> deactivating guidelines
>   high availability, line modules
>   redundancy mode of line modules
>     disruption in user sessions, forwarding data
>     reloading interfaces, routing tables from SRP
> destination address (DA), VRRP
> direct memory access (DMA)
>   receipt of packets for forwarding controller
>     by interface controller
>   receipt of packets for system controller
>     by interface controller
> disable-switch-on-error command
> disabled
>   high availability state
> disabled, line module high availability state
>   cold-restart of the router
>     when switchover occurs
>   retention in the same state
>     requirements not met
> disabled,, line module high availability state
>   criteria to move to initializing state
>     active module support for high availability
>     high availability mode configured
>     releases on standy and active modules are same
>     standby module is online, mirroring enabled
>     standby module support for high availability
>   router uses redundancy mode
> documentation set
>   comments on
> double fault window
>   scenarios that occur
>     stateful line module switchover after stateful SRP switchover is completed
>     stateful SRP switchover after line module high availability is completed
>     stateful SRP switchover before enabling line module high availability
>   simultaneous switchovers of
>     line module and SRP module
>   system behavior during
> downlink modules
>   ES2 4G LMs as
>     in an LNS device, stateful switchover
> drop events
>   on egress queues
>     not preserving across stateful switchover of LMs
> drop rates
>   on egress queues
>     not preserving across stateful switchover of LMs

E

> egress queues
>   drop events on
>     stateful switchover of LMs
>   drop rates on
>     stateful switchover of LMs
>   forwarding events on
>     stateful switchover of LMs
>   forwarding rates on
>     stateful switchover of LMs
> ES2 4G line modules
>   as access modules
>     in an LNS device for stateful switchover
>   as downlink modules
>     in an LNS device for stateful switchover
> ES2 4G LMs
>   installed with Service IOA
>     support for stateful line module switchover

F

> failover. See switchover
> file system synchronization mode
>   redundancy mode
> forwarding controller
>   receives packets from interface controller
>     using direct memory access
>   tables that point to failed modules
>     updated with stream IDs to new primary
>   transfer of packets from the interface controller
>     not preserved during stateful line module switchover
>   transfer of packets to the system controller
>     not preserved during stateful line module switchover
>   usage of stream ID
>     to identify connections from a specific slot
> forwarding controller database
>   mapping of the slot ID, stream ID, and traffic class
> forwarding events
>   on egress queues
>     not preserving across stateful switchover of LMs
> forwarding rates
>   on egress queues
>     not preserving across stateful switchover of LMs

H

> hardware
>   monitoring information 1, 2
> high availability
>   activating 1, 2
>   activating guidelines
>   deactivating 1, 2
>   IP interface priority 1, 2
>   overview
> high availability mode
>   redundancy mode
> high availability mode, line modules
>   brief pause in data forwarding
>     when secondary module becomes primary
>   initial bulk transfer of data
>     to newly assigned primary module
>   no impact on existing user sessions
>   synchronization of state and dynamic configuration
>     between primary and secondary LMs
>   transaction-based mirroring subsequently
>     to newly assigned primary module
> high availability pair
>   of line modules
>     unified ISSU disabled on the secondary
>     unified ISSU support on the primary
> high availability, line module See stateful line module switchover
> high availability, line modules
>   activating
>     launching Redundancy Configuration mode
>     specifying slots of primary and secondary modules
>   activating guidelines
>   deactivating
>   deactivating guidelines
>   error message displayed
>     when maximum limit is exceeded for pairs configured
>   maximum pairs that can be configured

I

> icr cluster
> ICR commands
>   interface
> icr interface
> ICR Options
>   icr-control-interface
>   priority command
>   timers-learn command
> ICR Partition
>   configuring 1, 2, 3, 4, 5
>   configuring, naming
>   radius
> ICR partition accounting
>   and dependence on Acct-Stop messages
>   configuring
>   disabling and enabling messages
>     sent to the RADIUS server
>   overview
>   processing in different scenarios
>     administrative switchover
>     complete chassis failure
>     line module or interface failure
>     transition of ICR partition states
> ICR Partition commands
>   naming
> ICR partition ID VSA
>   including in access and accounting messages
> ICR Partition ID VSA
>   transmitting to the virtual router
>     where ICR control interface is configured
>     where ICR partition is configured
> ICR Partition Options
>   advertise-mac 1, 2
>   control-interface 1, 2
>   group option 1, 2
>   use-default-mac 1, 2
> ICR Partitions
>   configuration example
>     backup ICR partition, S-VLAN based grouping
>     master ICR partition, S-VLAN based grouping
> ICR RADIUS commands
>   inclusion of icr-partition-id
>   radius icr-partition-accounting
> icr-partition
> in-service software upgrade. See unified ISSU
> initializing
>   high availability state
> initializing, line module high availability state
>   completion of operation
>     transition to active state
>   crtieria not met or previously matching criteria not complied
>     shifts to disabled state
>   events that occur
>     bulk synchronization of memory
>     mirroring of state and dynamic configuration
>   presence of unsupported application
>     shifts to disabled state
>   when a switchover occurs
>     system cold-restarts
> Interchassis Redundancy
>   heterogenous icr clusters
>   icr clusters
>   icr partition
> interface controller
>   forwards packets to system controller
>     using direct memory access
>     using Ethernet channel
>   operational image that runs on
>     and stateful line module switchover
>   receives packets destined for forwarding controller
>     using Ethernet channel
>   receives packets destined for system controller
>     using direct memory access
> Interim-Acct messages
>   ICR Partition ID VSA
> IOA slots
>   and SRP module combination
>     compatible with stateful line module switchover
> IP addresses
>   IP address owner, VRRP
>   primary, VRRP
>   VRRP 1, 2
> ip commands See also vrrp commands
>   ip address
>   ip vrrp
>   ip vrrp accept-data
>   ip vrrp advertise-interval
>   ip vrrp authentication-key
>   ip vrrp authentication-type
>   ip vrrp enable 1, 2
>   ip vrrp preempt
>   ip vrrp priority 1, 2
>   ip vrrp track
>   ip vrrp virtual-address 1, 2
> ip pim commands
>   ip pm dr-priority
> ISSU. See unified ISSU

L

> L2TP
>   after switchover to the secondary module occurs
>     restores operation data to the new primary
>   configuration and operation data
>     maintained in the line module
>     mirrored to the standby module
>   on the SRP module
>     handles line module events
>   restoration of configuration to the new primary
>     similarity with warm start during unified ISSU
> L2TP tunnels
>   data packets received on
>     preventing requests from LAC devices for sequence numbering
>     sequence number checking for
> LEDs
>   monitoring status
> line module high availability See stateful line module switchover
> line module high availability states
>   active
>   disabled
>   initializing
> line module redundancy
>   configuring
>   managing
>   modules enabled for
>     cannot be configured in a high availability pair
>   overview
>   requirements
>     E120 and E320 Routers
>     ERX7xx models and ERX14xx Models
> line modules
>   applications that support
>     stateful switchover
>   behavior of system functions
>     with stateful switchover configured
>   cold switchover of
>     loss of existign subscriber sessions
>     same behavior as line module redundancy
>   on E120 and E320 routers, components
>     forwarding controller
>     input/output adapter
>     interface controller
>   replacing
>     when stateful switchover is enabled
>   stateful switchover of
>     active or primary module
>     packet processing by the router
>     standby or secondary module
>   warm switchover of
>     preservation of subscriber sessions
>   with downlink interface to the LAC, reloading
>     not retaining user sessions during stateful switchover
>     not retaining user sessions with line module redundancy
> LNS devices
>   ES2 4G LMs as access modules
>     and stateful line module switchover
>   ES2 4G LMs as downlink modules
>     and stateful line module switchover
> LNS sessions
>   stateful switchover of
>     for routers that act as LNS devices
>     supported module and IOA combinations
> log messages
>   generated for stateful line module switchover
>     in response to manual settings
>     in response to system events
>   stateful line module switchover
>     transition between switchover states 1, 2
>     transition from active to disabled state
>     transition from disabled to active state
>     when HA is enabled
>   stateful SRP switchover
>     transition from pending to active state
>     when HA is enabled 1, 2, 3

M

> manuals
>   comments on
> master router
> Module Redundancy
>   switching example
>     primary Line Module, Spare Line Module
> modules
>   monitoring information 1, 2

N

> notice icons

P

> pending
>   high availability state
> performance impact
>   maximum tunneled PPP sessions
>     on the primary line module
> platform considerations
>   high availability
>   stateful line module switchover
> policy application
>   downloading policy attachments
>     using the SRP module
>   in the line module
>     policy definitions not stored in
>   transmission of policy attachments from SRP to LM
>     in a bulk manner
> policy attachments
>   transfer in a bulk operation
>     from SRP to line module
>     reduced time for download
> policy manager
>   stateful line module switchover safe
>     download of policy attachments
>     preservation of statistics after switchover
> policy statistics
>   preserved across line module switchover
>     green bytes and packets
>     red bytes and packets
>     saturated bytes and packets
>     transmit-unconditional bytes and packets
>     upper green bytes and packets
>     upper red bytes and packets
>     upper yellow bytes and packets
>     yellow bytes and packets
> PPP accounting statistics
>   preserved across line module switchover
>     Acct-Input-Octets RADIUS attribute
>     Acct-Input-Packets RADIUS attribute
>     Acct-Output-Octets RADIUS attribute
>     Acct-Output-Packets RADIUS attribute
>     IPv6-Acct-Input-Octets RADIUS attribute
>     IPv6-Acct-Input-Packets RADIUS attribute
>     IPv6-Acct-Output-Octets RADIUS attribute
>     IPv6-Acct-Output-Packets RADIUS attribute
> PPP application
>   after stateful line module switchover
>     replication of sessions on standby module
>   components on the line module
>     basic protocol
>     state machines in a running state
>     timers
>   echo requests for sessions on ES2 4G LM
>     handled by access module
>   echo requests for sessions on failed module
>     redirection to a different hardware
>   expiry of keepalives
>     time for the new primary to become active
>   mirrored storage data
>     reconstruction of
>   sessions alternating between up and down states
>     not retained during switchover
>   time for standby module to become active
>     dependent on configuration settings
> PPP echo reply messages
>   sent from access modules in LNS
>     in response to echo requests from clients
> PPP echo requests
>   handling by access module in LNS
>     during stateful switchover
>   stoppage of handling by access module in LNS
>     after stateful switchover is complete
> PPP subscriber sessions
>   on an LNS device in L2TP tunnels
>     echo requests handled by access module
>     terminated due to lack of keepalive responses
> primary line module
>   actions that trigger stateful switchover
>     disabling the slot
>     graceful switchover to secondary module
>     reloading the slot
>   collection of statistics from
>     for policy manager
>     for PPP applications
>   disabling the slot
>   disabling the slot of
>     secondary module becomes the primary
>   erasing the slot of
>     primary and secondary modules are cold booted
>   failure of
>     retaining active user sessions
>     running of diagnostic functions
>     stateful switchover to secondary module
>     subscriber disconnection for two minutes
>   performance impact, stateful switchover
>     maximum tunneled PPP sessions
>   reloading the slot of
>     secondary module becomes the primary
>   software fault occurs on
>     secondary module becomes the primary
>   timeout value
>     to reach the online state after router reboot

Q

> QoS
>   agent clients bind and register
>     to the QoS agent
>   configuration stored in line modules
>   settings mirrored to standby module
>   stateful line module switchover support
>     restoration of queues on subscriber interfaces
> queue manager
>   agent running on line modules
>     handling of forwarding controller updates
>   agents reside on line modules
>   initiation of requests to the connection manager
>     on reception of the controller up event
>   resides on the SRP
>   usage of queue ID
>     to identify connections

R

> RADIUS
> rebooting of the router
>   stateful line module switchover configured
>     primary module reaches online state
>     secondary module is not an online state
>     timeout for primary module to become online
> recovery of routers
>   from double failures
>     not supported
> redundancy
>   line module. See line module redundancy
>   SRP module. See SRP module redundancy
> redundancy commands
>   redundancy force-switchover 1, 2, 3
>   redundancy lockout
>   redundancy revert
>   redundancy revertive
>   srp switch
> redundancy modes
>   high availability
> redundancy modes, line modules
>   high availability
>   stateless switchover
> removal of IOAs
>   without powering down
>     stateful line module switchover not triggered
> replacement of line modules
>   stateful line module switchover enabled, action taken for failures
>     cold and warm switchovers of LMs in a HA pair
>     disabling the slots in which the LMs in a HA pair reside
>     reloading slot in which LMs in a HA pair reside
>     reloading the primary line module
>     reloading the secondary line module
>     removing IOAs from LMs in a HA pair without powering down
>     without erasing the interface settings
> resetting of subscriber sessions
>   with stateful line module switchover disabled, dependency on
>     configuration parameters applied
>     number of active user sessions
>     router models in network

S

> secondary line module
>   disabling the slot
>   disabling the slot of
>     cold boot is performed
>   erasing the slot of
>     line module high availability is disabled
>   mirroring of
>     subscriber details from failed primary
>   performance impact, stateful switchover
>     newly provisioned
>   preservation of active sessions
>     after a stateful switchover
>   reloading the slot of
>     cold boot is performed
>   software fault occurs on
>     cold boot is performed
>   taking over as
>     primary after stateful switchover
>   taking over as primary, timeout exceeded for primary
>     after system reboot
>   taking over as the primary
>     recovery of applications to a stable state
> sequence number checking
>   for packets on L2TP tunnels
>     not maintained during stateful switchover of LMs
>     setting recommendation for stateful switchover of LMs
> Service Availability
>   Features
>   ICR
>   Module redundancy
>   Stateful Line Module Switchover
>   Stateful SRP Switchover
>   Unified ISSU
>   VRRP
> show icr commands
>   show icr-partition
>   show icr-partitions
>   state
>   summary
> show ip commands
>   show ip vrrp 1, 2
>   show ip vrrp brief 1, 2
>   show ip vrrp neighbor
>   show ip vrrp neighbors
>   show ip vrrp statistics 1, 2, 3, 4
>   show ip vrrp statistics global 1, 2, 3
>   show ip vrrp summary 1, 2
>   show ip vrrp tracked-objects 1, 2
> show issu commands
>   show issu
>   show issu brief
>   show issu detail
> show redundancy commands
>   show environment 1, 2
>   show hardware 1, 2
>   show redundancy
>   show redundancy clients
>   show redundancy clients all
>   show redundancy detail
>   show redundancy history
>   show redundancy history detail
>   show redundancy history line-card slot
>   show redundancy history line-card slot detail
>   show redundancy line-card
>   show redundancy line-card slot
>   show redundancy srp
>   show redundancy srp detail
>   show redundancy switchover-history
> simultaneous switchover of
>   SRP and line modules
>     not supported
> SRP module redundancy
>   managing
> SRP modules
>   installing a redundant module
>   paired with IOAs
>     support for stateful line module switchover
>   reset button
>   simultaneous switchover with line modules
>     not supported
> stateful line module switchover
>   1:1 redundancy model
>   access modules in an LNS device
>   actions that trigger
>     disabling the slot of the primary module
>     graceful switchover to secondary module
>     rebooting the slot of the primary module
>   activating
>   activating guidelines
>   active module, primary
>   advantages of functionality
>     1:1 redundancy model
>     seamless preservation of subscriber sessions
>   and line module redundancy
>     cannot be enabled simultaneously
>   and stateful SRP switchover
>     configured and active on the same router
>   applications that do no support
>   applications that support
>     connection manager
>     forwarding controller
>     interchassis control protocol
>     L2TP
>     mirroring subsystem
>     policy manager
>     PPP
>     QoS
>     unified ISSU
>   available on the operational image
>     that runs on the interface controller
>   behavior of system functions
>     configured and disabled on LMs
>     configured and enabled on LMs
>     interoperation with line module redundancy
>     interworking with stateful SRP switchover
>     LM is in active or disabled switchover state
>     when the router is rebooting
>     when unified ISSU is performed
>   benefits of
>     enhanced reliability and resiliency
>     preservation of active client sessions
>     recovery of applications to a stable state
>     undisrupted forwarding of data
>   deactivating
>   deactivating guidelines
>   differences in keywords of commands
>     with stateful SRP switchover
>   disabled
>     forcible termination of user sessions
>   downlink modules in an LNS device
>   enabled on the router
>     retaining existing client connections
>     synchronization of applications to a stable state
>     uninterrupted forwarding on interfaces
>   for LNS sessions
>     active and standby Service IOAs supported
>     compatible SRP and SFM models
>     downlink and uplink LMs in an L2TP tunnel
>     L2TP tunnels and sessions supported
>     with the router as an LNS in an L2TP tunnel
>   forwarding controller tables
>     updated with stream IDs to new primary
>   guidelines for configuring
>   historical record of, not preserving
>     drop events on egress queues
>     drop rates on egress queues
>     forwarding events on egress queues
>     forwarding rates on egress queues
>   hot-swap of the IOA
>     in a managed environment
>   improving router availability
>   independent of stateful SRP switchover
>   interworking with unified ISSU
>     not supported on the secondary line module
>     supported on the primary line module
>   log messages
>     transition from active to disabled state
>     transition from disabled to active state
>   log messages generated during
>     in response to manual settings
>     in response to system events
>   maximum pairs that can be configured
>   modules enabled for
>     cannot be configured in a redundancy group
>   mutually exclusive of
>     line module redundancy
>   non-support of
>     1:N hot standby mode
>     automatic switchover of serial connection
>   not preserving packets flowing
>     between forwarding and interface controllers
>     between forwarding and system controllers
>   overview
>   performance impact
>     insertion of new secondary module
>     maximum PPP sessions on primary module
>   primary line module
>     continuation of data forwarding after failure of
>     failure of
>     mirroring of user sessions
>   scenarios of configuration
>   secondary line module
>     mirroring of subscriber sessions from primary
>     not preserving fluctuating sessions
>     taking over as primary
>   sequence number checking
>     for data packets on L2TP tunnels
>   similarity in cnonfiguration commands
>     with stateful SRP switchover
>   spare or standby module, secondary
>   supported line module, IOA combination
>   supported LM and IOA combinations
>     for stateful switchover of LNS sessions
>   system operations when enabled on the router
>   unavailable for setting up
>     forcible termination of user sessions
>   using status LEDs for monitoring
>     states of line modules
>   viewing
>     detailed history information for line module in a slot
>     information about starts and switchovers for line module in a slot
>     redundancy setting of line module in a slot
> stateful line module switchover commands
>   line-card switch
>   line-card switchmode high-availability slot
> stateful line module switchover, scenarios
>   not supported in software releases
>     restart of line modules
>   setting disabled on the router
>     disconnection of user sessions
>     excessive time for rebuilding user sessions
>     reestablishment of client connections
>     restart of line modules
> stateful SRP switchover
>   configuration independent of
>     stateful line module switchover
>   differences in keywords of commands
>     with stateful line module switchover
>   disruption of connection between ICs
>     reestablishment of ICC sessions
>     switch relearns MAC addresses
>   does not prevent root cause of reload or restart
>     similarity in behavior with stateful line module switchover
>   log messages
>     transition from pending to active state
>   similarity in configuration commands
>     with stateful line module switchover
>   simultaneously performed with
>     stateful line module switchover, double fault
> stateful SRP switchover., See also high availability
> stateless switchover mode, line modules
>   default behavior for redundant LMs
>   system events that occur
>   temporary halt in working of I/O modules
> states
>   high availability
> statistics
>   for policy manager
>     collection frequency from primary module
>     polling and sending to secondary line module
>   for PPP applications
>     collection frequency from primary module
>     polling and sending to secondary line module
>   last collected value used as baseline
>     on the primary line module
> status LEDs
>   monitoring redundancy state of SRP and line modules
>     OK LED
>     ONLINE LED
>     REDUNDANT LED
> status LEDs, monitoring
> subscriber sessions
>   preservation of active
>     during stateful line module switchover
> support, technical See technical support
> switchover
>   stateless

T

> technical support
>   contacting JTAC
> text and syntax conventions
> transmission of packets
>   between forwarding and interface controllers
>     not preserved during stateful line module switchover
>   between forwarding and system controllers
>     not preserved during stateful line module switchover

U

> unified ISSU
>   disabled on the secondary module
>     in a high availability pair
>   support on primary module
>     in a high availability pair
> unified ISSU (in-service software upgrade)
>   AAA support
>   application support
>   ATM support
>     ATM port date rate
>     ILMI sessions
>     OAM CC effects
>     OAM VC integrity
>     VC and VP statistics
>   DHCP support
>     common component
>     external server
>     packet capture
>     relay and relay proxy
>   DHCP support:relay and relay proxy
>   DoS protection support
>   Ethernet support
>     ARP entries
>     LAG
>     port data rate
>     VLAN statistics
>   FTP support
>   halting during initialization
>   halting during upgrade
>   initialization phase
>     application data on standby SRP module
>     line module arming
>     SNMP traps
>   interoperation with
>     stateful line module switchover
>   IPv6
>   IS-IS support
>     graceful restart
>     high link cost
>   L2TP support
>   layer 3 protocol traffic forwarding
>   OSPF support
>     dead interval
>     graceful restart
>     high link cost
>   overview
>   phases
>     initialization
>     overview of
>     service restoration
>     upgrade
>   PIM support
>   platform
>   procedure for upgrade
>   references
>   requirements
>     hardware 1, 2
>     software
>     traffic forwarding
>     verification in upgrade phase
>   restoring original router state 1, 2
>   router behavior
>   service restoration phase 1, 2
>   SONET/SDH support
>   subscriber support
>     logins
>     statistics
>   support, application
>   T3 support
>   TACACS+ support
>   terms
>   timer settings for routing protocol timers
>   upgrade phase
>     exceptions
>     line module control plane
>     line module forwarding plane upgrade
>     process steps
>     setup
>     SRP module switchover
>     verification requirements
>   upgrade procedure
> unified ISSU (in-service software upgrade):DHCP support
>   local server
> upgrading software
>   high availability

V

> virtual MAC address
> virtual router ID (VRID). See VRID
> Virtual Router Redundancy Protocol (VRRP). See VRRP
> VRID (virtual router ID)
>   configuration
>   creating 1, 2
>   router election rules 1, 2
> vrrp
>   platform
> VRRP
> VRRP (Virtual Router Redundancy Protocol)
>   advertisement interval
>   advertisement messages
>   authentication key
>   authentication type
>   backup router 1, 2, 3, 4, 5
>   configuration examples 1, 2, 3
>   configuring
>   how it works
>   implementation 1, 2
>   MAC address
>   master router
>   monitoring 1, 2, 3, 4
>   overview
>   preemption 1, 2
>   router election rules 1, 2
>   router priority
>   VLAN support
>   VRRP router defined
> vrrp commands
>   ip vrrp
>   ip vrrp accept-data
>   ip vrrp advertise-interval
>   ip vrrp authentication-key
>   ip vrrp authentication-type
>   ip vrrp enable 1, 2
>   ip vrrp preempt 1, 2
>   ip vrrp priority
>   ip vrrp track
>   ip vrrp virtual-address
> VRRP commands
>   icr

W

> warm restart
>   IP interface priority 1, 2
> warm restart, line modules
>   events that occur
>     denial of new user session login attempts
>     preservation of active user sessions
>     preservation of data forwarding through chassis
>     prevention of configuration changes