VRRS improves the scalability of FHRP. VRRS provides a stateless redundancy service to applications (VRRS clients) by monitoring VRRP. VRRS provides a database of the current VRRP state and operates without maintaining sessions or keeping track of previous states of the clients and servers with which it communicates. VRRP acts as a VRRS server. VRRS clients are other Cisco IOS processes or applications that use VRRP to provide or withhold a service or resource dependent upon the state of the group.

VRRS by itself is limited to maintaining its own state. Linking a VRRS client to a VRRP group provides a mechanism that allows VRRS to provide a service to client applications so they can implement stateless or stateful failover. Stateless failover is failover without syncing of state. Stateful failover requires communication with a nominated backup before failure so that operational data is not lost when failover occurs.

VRRP provides server support for VRRS. The VRRP server pushes state and status information to VRRS when an internal update occurs. VRRS updates its internal database upon receiving a server update, and then sends push notifications to each of the VRRS clients associated with the shared name. Clients are interested in the protocol state, virtual MAC address, and virtual IP address information associated with a group. The association name between a client and a VRRP group is a character name string. The information provided by VRRS allows clients to perform various activities that are dependent on the state of the associated VRRP group.

VRRP notifies VRRS of its current state (master, backup, or nonoperational INIT). The VRRP state is then passed on to clients or acted on by a plug-in. A VRRP group should be configured with a name to activate VRRS. Clients should be configured with the same name to bind them with VRRS.

The VRRP group name associates the VRRP group with any clients that are configured as part of VRRS with the same name.

VRRP acts as the VRRS server. Clients act on the VRRP server state. When a VRRP group changes state, VRRS clients act by altering their behavior (performing tasks such as shutting down interfaces or appending accounting logs) depending on the state received from VRRS.

The following can be VRRS clients:

• PPP over Ethernet (PPPoE) subinterfaces
• Access Node Control Protocol (ANCP) subinterfaces
• VRRS Interface-state plug-in
• VRRS MAC-Address plug-in
• VRRS Accounting plug-in

VRRS plug-ins extend the failover of VRRP without the need for configuring VRRP groups on all subinterfaces. Configuring a VRRS plug-in on subinterfaces is a substitute for having to configure multiple VRRP groups on many subinterfaces. Plug-ins provide a light-weight version of VRRP and scale better than a fully configured VRRP group. The state of the plug-ins follows the VRRP server state. Client plug-ins are configured on other subinterfaces that share the same physical interface as VRRP.

The VRRS MAC-Address plug-in provides a mechanism for controlling a virtual MAC address associated with the primary interface IP address. If the VRRS MAC-Address plug-in is configured on an interface, and a VRRP group shares a name association with the plug-in, then a VRRS active state associates a virtual MAC address with the configured primary IP address.

The VRRS MAC-Address plug-in is only interested in the VRRS active state, which is interpreted as up. All other states are interpreted as down. When the state is up and the additional interface criteria listed below have been met, then the VRRS MAC-Address plug-in provides the following services:

• Overwrites the interface IP address ARP table with a virtual MAC address provided by VRRS
• Inserts the virtual MAC address provided by VRRS into the MAC address filter of the interface
• Controls the ARP reply mechanism by substituting a VRRS-provided virtual MAC address
• Broadcasts unsolicited ARP messages that include the VRRS virtual MAC address

When VRRS is in a nonactive state, the virtual MAC address is unassociated from the primary IP address.

When you use the VRRS MAC-Address plug-in, the VRRS Interface-State plug-in must also be used in order to prevent address conflicts with other redundant members.

Additional interface criteria:

• Interfaces must be configured with an interface IP address.
• Interfaces must be in the line-protocol up state.
• Other FHRP protocols cannot be configured on the interface; these include HSRP, VRRP, and GLBP.

The VRRS MAC-Address plug-in is associated with a VRRS group name by configuring the vrrs follow name command.

The VRRS Interface-State plug-in provides a mechanism for controlling the line-protocol state of a subinterface based on the state of VRRP. The VRRS Interface-State plug-in is an extension of the VRRS, and is directly controlled by the push events associated with the VRRS. If the plug-in is configured on an interface, and a VRRP group shares a name association with the VRRS plug-in, then a VRRS active state allows the line- protocol state of the interface to be up. A VRRS nonactive state will cause the line protocol of the interface to be down.

Note	When first configured, the interface line protocol may immediately change to the down state until the VRRS state is confirmed as up.

The VRRS Interface-State plug-in is associated with a VRRS group name by configuring the vrrs follow name command.

The Interface-State plug-in restricts the operation of the no shutdown command. When an interface is line-protocol down, the interface state will not go up.

The VRRS Accounting plug-in provides a configurable AAA method list mechanism that provides updates to a RADIUS server when a VRRS group transitions its state.

The VRRS accounting plug-in is an extension of existing AAA system accounting messages. The VRRS Accounting plug-in provides accounting-on and accounting-off messages and an additional Vendor-Specific Attribute (VSA) that sends the configured VRRS name in RADIUS accounting messages. The VRRS name is configured using the vrrp name command in interface configuration mode.

The VRRS Accounting plug-in sends an accounting-on message to RADIUS when a VRRS group transitions to the master state, and it sends an accounting-off message when a VRRS group transitions from the master state.

The following RADIUS attributes are included in VRRS accounting messages by default:

• Attribute 4, NAS-IP-Address
• Attribute 26, Cisco VSA Type 1, VRRS
• Attribute 40, Acct-Status-Type
• Attribute 41, Acct-Delay-Time
• Attribute 44, Acct-Session-Id

Accounting messages for a VRRS transitioning out of master state are sent after all PPPoE accounting stop messages for sessions that are part of that VRRS.

The VRRS accounting type is implemented by AAA to support VRRS accounting.

1.    enable

2.    configure terminal

3.    interface type number

4.    ip address ip-address mask [secondary [vrf vrf-name]]

5.    vrrp group-number name [vrrp-group-name]

6.    vrrp group ip ip-address [secondary]

7.    vrrp delay {minimum seconds [reload seconds] | reload seconds}

1.    enable

2.    configure terminal

3.    interface type number.subinterface

4.    ip address ip-address mask [secondary [vrf vrf-name]]

5.    vrrs follow name

6.    vrrs interface-state

7.    vrrs mac-address [arp [interval seconds] [duration seconds]]

8.    Repeat Steps 3 through 7 to configure additional subinterfaces.

1.    enable

2.    configure terminal

3.    aaa accounting vrrs { default | list-name start-stop [method1 [method2...]]

4.    aaa attribute list list-name

5.    attribute type name value [service service] [protocol protocol] [mandatory] [ tag tag-value]

6.    exit

7.    vrrs vrrs-group-name

8.    accounting delay delay

9.    accounting method {default | accounting-method-list}

10.    attribute list list-name

1.    debug vrrp vrrs

2.    debug vrrs accounting {all | errors | events}

3.    debug vrrs infra {all | client | events | server}

4.    debug vrrs plugin {all | arp-packet | client | database | if-state | mac | process | sublock | test}

5.    show vrrs clients

6.    show vrrs group [group-name]

7.    show vrrs plugin database

8.    show vrrs summary

Router# debug vrrp vrrs

VRRP VRRS debugging is on
*Feb  5 09:29:47.005: VRRP: Registered VRRS group "name1"
*Feb  5 09:29:53.237: VRRP: Updated info for VRRS group name1
*Feb  5 09:30:14.153: VRRP: Unregistered VRRS group "name1"
*Feb  5 09:30:14.153: VRRP: Registered VRRS group "name2"
*Feb  5 09:30:22.689: VRRP: Unregistered VRRS group "name2"

Router# debug vrrs accounting

00:16:13: VRRS/ACCT/EV: entry create for abc(0x4E8C1F0)
00:16:13: VRRS/ACCT/EV: abc(0x4E8C1F0 12000006) client add ok2(No group)

Router# debug vrrs infra

*Sep 9 16:09:53.848: VRRS: Client 21 is not registered
*Sep 9 16:09:53.848: VRRS: Client 21 unregister failed
*Sep 9 16:09:53.848: VRRS: Client VRRS TEST CLIENT registered, id 21
*Sep 9 16:09:53.848: VRRS: Client 21 add, group VRRP-TEST-1 does not exist, allocating...
*Sep 9 16:09:53.848: VRRS: Client 21 add to VRRP-TEST-1. Vrrs handle F7000001, client
handle FE720
*Sep 9 16:09:53.848: VRRS: Server VRRP add, group VRRP-TEST-1, state INIT, vrrs handle
F7000001

Router# debug vrrs plugin

Feb 17 19:15:38.052: VRRS-P(mac): GigEth0/0/0.1 Add 0000.12ad.0001 to MAC filter, using
(afilter_add) 
Feb 17 19:15:38.053: VRRS-P(mac): Active count increase to (2) for MAC : 0000.12ad.0001 

Router# show vrrs clients

ID  Priority  All-groups  Name
------------------------------
1   High      No          VRRS-Plugins
2   Low       Yes         VRRS-Accounting
3   Normal    No          PPPOE-VRRS-CLIENT 

Router# show vrrs group DT-CLUSTER-3

DT-CLUSTER-3
Server Not configured, state INIT, old state INIT, reason Protocol 
  Address family IPv4, Virtual address 0.0.0.0, Virtual mac 0000.0000.0000 
  Active interface address 0.0.0.0, standby interface address 0.0.0.0 
Client 5 VRRS TEST CLIENT, priority Low 

Router# show vrrs plugin database

VRRS Plugin Database 
------------------------------------------------ 
Name = VRRS_NAME_1 
Server connection = Live 
State = Disabled 
MAC addr = 0000.5e00.0101 
Test Control = False 
Client Handle = 3741319170 
Interface list = 
                 gige0/0/0.2 
                 gige0/0/0.3 

Router# show vrrs summary

Group                                             Server State Virtual-address
------------------------------------------------------------------------------
DT-CLUSTER-3                                      UNKNOW INIT    0.0.0.0 
DT-CLUSTER-2                                      VRRP   BACKUP 11.1.1.1 
DT-CLUSTER-1                                      VRRP   ACTIVE  1.1.1.1