IEEE 801.ak - MVRP and MRP
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Table Of Contents
Restrictions for EEE 802.1ak - MVRP and MRP
Information About EEE 802.1ak - MVRP and MRP
MVRP Interoperability with Other Pruning Protocols
VTP in Transparent or Off Mode
VTP in Server or Client Mode and VTP Pruning is Disabled
VTP in Server or Client Mode and VTP Pruning is Enabled
MVRP Interoperation with Non-Cisco Devices
MVRP Interoperability with Other Software Features and Protocols
Switchport Blocking Unicast Traffic
Enabling Automatic Detection of MAC Addresses
Enabling MVRP Dynamic VLAN Creation
Changing the MVRP Registrar State
Troubleshooting the MVRP Configuration
Configuration Examples for IEEE 802.1ak -MVRP and MRP
Enabling Automatic Detection of MAC Addresses: Example
Enabling Dynamic VLAN Creation: Example
Changing the MVRP Registrar State: Example
Feature Information for IEEE 802.1ak - MVRP and MRP
IEEE 802.1ak - MVRP and MRP
First Published: November 14, 2008Last Updated: March 6, 2009Implementation of the IEEE 802.1ak standard allows for dynamic registration and deregistration of VLANs on ports in a VLAN bridged network. This document describes Multiple Registration Protocol (MRP) and Multiple VLAN Registration Protocol (MVRP) as implemented in accordance with the IEEE 802.1ak standard.
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Restrictions for EEE 802.1ak - MVRP and MRP
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Restrictions for EEE 802.1ak - MVRP and MRP
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Information About EEE 802.1ak - MVRP and MRP
IEEE 802.1ak, also known as Multiple Registration Protocol (MRP), allows dynamic registration and deregistration of VLANs on ports in a VLAN bridged network. IEEE 802.1ak provides performance improvement over the GVRP and GMRP protocols with more efficient Protocol Data Units (PDUs) and protocol design. This feature implements MRP and MVRP as specified in the IEEE 802.1ak standard.
In a VLAN bridged network, it is desirable to restrict unknown unicast, multicast, and broadcast traffic to those links which the traffic must use to access the appropriate network devices. In a large network, localized topology changes can affect the service over a much larger portion of the network. IEEE 802.1ak replaces GARP with MRP offering much improvement over resource utilization and conservation of bandwidth.
With the 802.1ak MRP attribute encoding scheme, MVRP only needs to send one PDU that includes the state of all 4094 VLANs on a port. MVRP also includes the transmission of a Topology Change Notification (TCN) for individual VLANs. This is an important feature for service providers because it allows them to localize topology changes. Figure 1 illustrates MVRP deployed in a provider network on provider and customer bridges.
Figure 1 MVRP Deployed on Provider and Customer Bridges
In the Metro Ethernet provider network, the use of thousands of VLANs is likely. Most providers do not wish to filter traffic by destination Mac Addresses. Hence, a pruning protocol like MVRP becomes important.
In Figure 2, redundant links are configured between the access switch and two distribution switches on the cloud. When the link with VLAN 104 fails over, MVRP need to send only one TCN for VLAN 104. Without MVRP, an STP TCN would have to be sent out for the whole MST region (VLANs1-1000), causing unnecessary network interruption.
STP sets the new variable tcDetected for MVRP to decide whether to send a New message (hence, references to MVRP TCN). When an attribute declaration marked as new is received on a given port, any entries in the filtering database for that port and for that VLAN are removed. This allows MVRP to flush the filtering database entries rapidly on a per-VLAN basis following a topology change.
Figure 2 MVRP TCN Application
Dynamic VLAN Creation
Virtual Trunking Protocol (VTP) is a Cisco proprietary protocol that distributes VLAN configuration information across multiple devices within a VTP domain. When VTP is running on MVRP-aware devices, all of the VLANs allowed on the Cisco bridged LAN segments are determined by VTP. MVRP dynamic VLAN creation can be enabled only when the VTP mode on the switch is set to transparent. When dynamic VLAN creation is disabled, the MVRP trunk ports can register and propagate the VLAN messages only for the existing VLANs. MVRP PDUs and MVRP messages for the non-existing VLANs are discarded.
For a switch to be configured in full compliance with the MVRP standard, the switch VTP mode must be transparent and MVRP dynamic VLAN creation must be enabled.
MVRP Interoperability with Other Pruning Protocols
This section discusses MVRP interoperablity with other pruning protocols.
cGVRP
The GARP VLAN Registration Protocol (GVRP) is defined in IEEE 802.1q-1998 to allow dynamic registration and deregistration of VLANs on ports. Compact GVRP (cGVRP) is a modification of GVRP that reduces the number of packets required to transmit the state of a port. In addition, cGVRP provides rapidly VLAN pruning from point-to-point links without using Leave timer or Leave All garbage collection messaging. cGVRP is the pre-standard of MVRP. Both of cGVRP and MVRP are sharing one common VLAN/PM database. Hence, they can interoperate with each other, however both MVRP and cGVRP cannot be configured and running on the same device.
Compact GVRP has two modes: Slow Compact Mode, and Fast Compact Mode. A port can be in Fast Compact Mode if it has one GVRP enabled peer on the same LAN segment, and the peer is capable of operating in Compact Mode. A port is in Slow Compact Mode if there are multiple GVRP participants on the same LAN segment operating in Compact Mode.
VTP
The VLAN Trunking Protocol (VTP) is a Cisco proprietary protocol that distributes VLAN configuration information across multiple devices within a VTP domain. VTP Pruning is an extension of VTP. It has its own Join message that can be exchanged with VTP PDUs. VTP PDUs can be transmitted on both .1Q trunks and ISL trunks. A VTP-capable device is in either one of the three VTP modes: Server, Client, or Transparent.
When VTP Pruning and MVRP are both enabled globally, VTP Pruning is run on ISL trunks, and GVRP is run on .1Q trunks.
VTP in Transparent or Off Mode
When VTP is in transparent or off mode, VTP PDUs are not processed and hence VTP pruning is not supported. The device operates like a dot1q device.
Upon receiving of a MVRP Join message for a VLAN on a port, the port is transmits broadcast, multicast, and unknown unicast frames in that VLAN and adds the traffic definition to a MAP port set for that VLAN. The mapping is undone when the VLAN is no longer registered on the port.
For each and every VLAN in the local VLAN database, if there is a local association, such as, an access port, SVI, or a VTP trunk port forwarding in the VLAN, MVRP issues a Join request to each MAD instance and an MVRP Join message is sent out on each corresponding MVRP port.
Dynamic VLAN creation can be enabled in VTP transparent mode. If it is enabled and the VLAN registered by a Join message does not exist in the VLAN database in the device, then the VLAN will be created.
VTP in Server or Client Mode and VTP Pruning is Disabled
MVRP behaves like VTP in transparent, or off, mode with the exception that dynamic VLAN creation is not allowed.
VTP in Server or Client Mode and VTP Pruning is Enabled
When MVRP and VTP are both enabled on the same device, these two protocols have to communicate and exchange pruning information. VTP pruning and MVRP are mutually exclusive and cannot be configured on the same interface, but VTP protocol with pruning disabled and MVRP can be supported on the same interface.
When VTP receives a VTP Join message on a VTP trunk, the MVRP application needs to be notified so that Join request can be posted to the state machines in the MAD instances associated with MVRP ports, and MVRP Join can be sent out on the MVRP ports to the MVRP network. When VTP pruning removes a VLAN on a VTP trunk, MVRP sends a Leave request to all the MAD instances. If the MAD instances receive a Leave request event, then a Leave or Empty message is sent out on the MVRP ports to indicate that the device is no longer interested in declaring the VLAN.
When a MVRP Join message is received on a MVRP port, in addition to propagating this event to other MVRP ports in the same MAP context, the device also notifies the VTP pruning component so that VTP pruning can send out a VTP Join message out the VTP trunk ports to the VTP network. Similarly, if MVRP learns that a VLAN is no longer declared by the neighboring devices, it needs to indicate a withdrawal event to the VTP pruning component. VTP pruning will then check if it has to continue sending VTP Join message to the VTP network.
For VLANs that are configured to be VTP pruning non-eligible on the VTP trunks, the VTP pruning state variables are set to Joined for the VLANs. MVRP Join requests are sent to those VLANs through the MVRP ports.
MVRP Interoperation with Non-Cisco Devices
Non-Cisco devices can interoperate with a Cisco device only through dot1q trunks.
MVRP Interoperability with Other Software Features and Protocols
This section describes interoperability with protocols, both supported and unsupported in conjunction with MVRP. The following protocols are addressed:
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802.1x and Port Security
802.1x authenticates and authorizes a port after it becomes link-up, but before DTP negotiation occurs and MVRP runs on a port. Port security also works independently of MVRP.
When MVRP is globally enabled, the mac-address auto detect and provision feature is turned on by default. This can disable MAC learning under certain scenarios. This may prevent Port Security from working properly. For example, on Port Security ports, even though the number of streams exceeds the configured maximum number of mac address, no violation will be marked because the MAC learning is disabled in L2-Mgr and hence Port Security will not know there are more streams coming into the port. Use caution when turning on automatic MAC learning (using the mvrp mac-learning auto command) while Port Security is configured on the interfaces.
DTP
DTP negotiates the port mode (trunk vs. non-trunk) and the trunk encapsulation type between two DTP enabled ports. After negotiation DTP may set the port to either ISL trunk, dot1Q trunk, or non trunk. DTP negotiation occurs after ports become link-up and before they become forwarding in spanning trees. If MVRP is administratively enabled on a port and the device, it should be initialized after the port is negotiated to be a .1Q trunk.
EtherChannel
When multiple dot1Q trunk ports are grouped by either Port Aggregation Protocol (PAgP) or Link Aggregation Control Protocol (LACP) to become an etherchannel, the etherchannel can be configured as an MVRP participant. The physical ports in the etherchannel cannot be MVRP participants by themselves. Since an etherchannel is treated like one virtual port by STP, the MVRP application can learn the STP state change of the etherchannel just like any physical port. The MAP context is mapped to the etherchannel interface, but not to the channel member ports.
Flexlink
Flexlink is a pair of switchport interfaces, one is active and the other is standby. When the active link fails, the standby interface takes over. The standby interface is set to blocking in both software and hardware. Hence, no data frames are allowed on the standby port except protocol PDUs.
MVRP must declare VLANs on STP forwarding ports but not on the blocking ports. If Flexlink is enabled, it must declare VLANs on the active ports but not on the standby ports. But when the flexlink standby port takes over the link-down active port, MVRP must be informed so that it can declare VLANs on this new active port.
High Availability
High Availability (HA) is a redundancy feature in Cisco IOS software. On platforms that support HA and State SwitchOver (SSO) and ISSU, many features and protocols my resume working in a couple of seconds after the system encounters a failure such as a crash of the active supervisor in a Catalyst 7600 switch. MVRP needs to be configured to enable user configurations, and protocol states should be synched to a standby system. If there is a failure of the active system, the MVRP in the standby system which now becomes active without a restart, has all the up-to-date VLAN registration information.
ISSU/EFSU
In-Service Software Upgrade (ISSU)/Enhanced Fast Software Upgrade (EFSU) allows for the upgrade or downgrade of software (ION) version with improved performances. It relies on the Stateful Switchover (SSO)/Nonstop Forwarding (NSF) architecture to allow different software versions on the active and standby supervisor to interact in a stateful manner. It is the intermediate phase towards ISSU/MDR for which the upgrade or downgrade will occur in a stateful manner (with the same performances as an SSO switchover). MVRP will be serviced by the ISSU client identified as ISSU_MVRP_CLIENT_ID and ISSU compliant.
L2PT
Layer 2 Protocol Tunneling (L2PT) allows Layer 2 protocol data units (PDUs), such as Cisco Discovery Protocol (CDP), Spanning Tree Protocol (STP), Trunking Protocol (VLANs/VTP) (VTP) and Link Layer Discovery Protocol (LLDP) to be tunneled through a network. Without Layer 2 protocol tunneling, tunnel ports drop those protocol packets.
MVRP PDUs in Q-bridges (with 01-80-C2-00-00-21 frames) are not tunneled through the network by L2PT; only CDP, STP, VTP and LLDP PDUs are tunneled by L2PT.
MMRP
Multiple Multicast Registration Protocol (MMRP) is another dot1ak application for multicast registration protocol. MVRP and MMRP work independently and should be configured separately. MVRP and MMRP share the same MRP implementation.
REP
Resilient Ethernet Protocol (REP) is a Cisco proprietary protocol used to achieve fast reconvergence time in ring topologies aggregated by at least a pair of switches. It offers VLAN load balancing and an arbitrary number of switches can be put in a ring.
REP interface comes up in a blocked state, and, until it knows it is safe to unblock, it remains in blocked state. There are three port roles:
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MVRP must declare VLANs on the Open Ports and declare non-blocking VLANs on the Alternate Ports. When the REP Alternate Port takes over the link-down Open Port, MVRP must be informed so that it can declare all VLANs on the new Open Port.
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SPAN
Switched Port Analyzers (SPAN) work with VTP pruning ports. MVRP ports should be configured as either a SPAN source or destination port.
Switchport Blocking Unicast Traffic
The switchport block unicast command administratively blocks flooded traffic by disabling forwarding of unknown unicast and multicast addresses on a particular switchport interface. MVRP also prunes flooded traffic at runtime. These two features are mutually exclusive and cannot be configured on the same interface.
STP
Spanning Tree Protocol (STP) may run in one of the three STP modes: Multiple Spanning Tree (MST), Per VLAN Spanning Tree (PVST), or Rapid PVST. An STP mode range causes the forwarding ports to leave the forwarding state as STP has to reconverge. The reconvergence might cause MVRP to have its own topology changes as Join s may be received on some new forwarding ports, and Leave timers may expire on some other ports.
UDLR
Unidirectional link routing (UDLR) limits frames in one direction and MVRP is a two-way communication protocol. Hence, UDLR and MVRP are mutually exclusive and cannot be configured on the same port.
VLANs with MVRP
This section discusses topics related to VLANs with MVRP.
VLAN Mapping
VLAN Mapping, also known as VLAN translation, maps 802.1q frames from the original VLAN (the VLAN indicated in the 802.1q tag in the frames) to a different VLAN on a device. In other words, it is a translated VLAN. If VLAN Mapping is enabled, MVRP translates the original VLAN IDs in the coming MVRP PDUs to the translated VLAN ids and then processes the request. Similarly, before MVRP sends PDUs out to a port, it inserts the original VLAN IDs in the PDUs, if VLAN Mapping is enabled on the port.
VLAN Mapping is an expensive operation to support on MVRP because it requires a lookup for each VLAN coming in with the MVRP PDU, and another lookup when the MVRP PDU is sent out.
All VLAN Tagging
All VLAN tagging, also known as, Native VLAN tagging, causes the frames sent in the native VLAN of the dot1q trunk ports to be encapsulated with a dot1q tag. Other MVRP participants on the LAN may not be able to accept tagged MVRP PDUs and can cause network issues. You should design your network carefully when both MVRP and Native VLAN tagging are configured.
Private VLANs
Private VLANs provide Layer 2 isolation between ports within the same private VLAN. There are three types of private VLAN ports:
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VTP
VTP version 3 expands the range of VLANs that can be created and removed via VTP. VTP Pruning is available for VLANs 1 - 1005 only.
How to Configure MVRP
MVRP can be configured on the entire switch or on specific interface. MVRP is operational on an interface only if it is administratively enabled both globally and at the interface level. Only when MVRP is operational on an interface can MVRP PDUs be transmitted out of the interface, and other MVRP-related operations be effective. The interface must be a forwarding dot1q trunk. The following tasks are included:
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Enabling MVRP
When MVRP is enabled globally, it is operational on 802.1q trunk ports only. To be enabled on an interface, it must be configured on the specific interface. To enable MVRP, complete the following steps.
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DETAILED STEPS
Enabling Automatic Detection of MAC Addresses
You can enable automatic detection of (and provisioning for) MAC addresses globally on the switch. MVRP automatic detection of MAC addresses is disabled by default. To enable MVRP automatic detection of MAC addresses on VLANs, complete the following steps.
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DETAILED STEPS
Enabling MVRP Dynamic VLAN Creation
VLANs can be created dynamically when MVRP is enabled. This can be done only if VTP is in transparent mode. To enable an MVRP dynamic VLAN, complete the following steps.
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Changing the MVRP Registrar State
You can set the registrar in an MRP Attribute Declaration (MAD) instance associated with an interface to one of three possible states. An MRP-aware device can be in one of the following participant states:
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The MRP protocol allows one participant per application in an end station, and one per application per port in a bridge.
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Troubleshooting the MVRP Configuration
Perform this task to troubleshoot the MVRP configuration.
Use the show mvrp summary and show mvrp interface commands to display configuration information and interface states, and the debug mvrp command to enable all or a limited set of output messages related to an interface.
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Example
The following is sample output from the show mvrp summary command. This command can be used to display the MVRP configuration at the device level.
Router# show mvrp summaryMVRP global state : enabledMVRP VLAN creation : disabledVLANs created via MVRP : 20-45, 3001-3050Learning disabled on VLANs : noneThe following is sample output from the show mvrp interface command. This command can be used to display MVRP interface details of the administrative and operational MVRP states of all or one particular IEEE 802.1q trunk port in the device.Router# show mvrp interfacePort Status Registrar StateFa3/1 off normalPort Join Timeout Leave Timeout Leaveall TimeoutFa3/1 201 600 700 1000Port Vlans DeclaredFa3/1 nonePort Vlans RegisteredFa3/1 nonePort Vlans Registered and in Spanning Tree Forwarding StateFa3/1 noneConfiguration Examples for IEEE 802.1ak -MVRP and MRP
This section provides the following configuration examples:
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Enabling MVRP: Example
The following example shows how to enable MVRP.
Router> enableRouter# configure terminalRouter(config)# mvrp global%MVRP is now globally enabled. MVRP is operational on 802.1q trunk ports only.Router(config)# interface fastethernet2/1Router(config-if)# exitRouter(config)# mvrp globalRouter(config)# interface fastethernet2/2Router(config-if)# exitRouter(config)# mvrp globalRouter(config)# endEnabling Automatic Detection of MAC Addresses: Example
The following example shows how to enable the automatic detection of MAC addresses.
Router> enable
Router# configure terminal
Router(config)# gvrp mac-learning auto
Router(config)# exit
Enabling Dynamic VLAN Creation: Example
The following example shows how to enable dynamic VLAN creation.
Router> enable
Router# configure terminal
Router(config)# vtp mode transparent
Router(config)# gvrp vlan create
Router(config)# end
Changing the MVRP Registrar State: Example
The following example shows how to change the MVRP registrar state.
Router> enable
Router# configure terminal
Router(config)# mvrp registration normal
Router(config)# end
Additional References
The following sections provide references related to the IEEE 802.1ak - MVRP and MRP feature.
Related Documents
IP LAN switching commands: complete command syntax, command mode, defaults, usage guidelines, and examples
Information about cGVRP
"cGRVP" module
Standards
MIBs
RFCs
No new or modified RFCs are supported by this feature, and support for existing RFCs has not been modified by this feature.
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Technical Assistance
Feature Information for IEEE 802.1ak - MVRP and MRP
Table 1 lists the release history for this feature.
Not all commands may be available in your Cisco IOS software release. For release information about a specific command, see the command reference documentation.
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