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Cisco IOS XE IPv6 Configuration Guide, Release 2
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Start Here: Cisco IOS XE Software Release Specifics for IPv6 Features
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Implementing IPv6 Addressing and Basic Connectivity
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Implementing ADSL and Deploying Dial Access for IPv6
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Implementing Bidirectional Forwarding Detection for IPv6
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Implementing DHCP for IPv6
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Implementing EIGRP for IPv6
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Implementing IS-IS for IPv6
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Implementing IPv6 for Network Management
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Implementing Multiprotocol BGP for IPv6
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Implementing IPv6 Multicast
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Implementing OSPF for IPv6
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Implementing QoS for IPv6
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Implementing RIP for IPv6
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Implementing Traffic Filters and Firewalls for IPv6 Security
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Implementing Static Routes for IPv6
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Implementing Tunneling for IPv6
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Implementing IPsec in IPv6 Security
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Table Of Contents
Prerequisites for IPv6 Multicast
Restrictions for IPv6 Multicast
Information About IPv6 Multicast
IPv6 Multicast Routing Implementation
Multicast Listener Discovery Protocol for IPv6
Explicit Tracking of Receivers
Protocol Independent Multicast
IPv6 Multicast Process Switching and Fast Switching
Multiprotocol BGP for the IPv6 Multicast Address Family
How to Implement IPv6 Multicast
Enabling IPv6 Multicast Routing
Customizing and Verifying MLD on an Interface
Configuring Explicit Tracking of Receivers to Track Host Behavior
Resetting the MLD Traffic Counters
Clearing the MLD Interface Counters
Configuring Bidirectional PIM and Displaying Bidirectional PIM Information
Resetting the PIM Traffic Counters
Clearing the PIM Topology Table to Reset the MRIB Connection
Configuring a BSR and Verifying BSR Information
Configuring to send PIM RP Advertisements to the BSR
Configuring IPv6 Multiprotocol BGP
Configuring an IPv6 Peer Group to Perform Multicast BGP Routing
Advertising Routes into IPv6 Multiprotocol BGP
Redistributing Prefixes into IPv6 Multiprotocol BGP
Assigning a BGP Administrative Distance
Generating Translate Updates for IPv6 Multicast BGP
Clearing IPv6 BGP Route Dampening Information
Clearing IPv6 BGP Flap Statistics
Verifying MFIB Operation in IPv6 Multicast
Resetting MFIB Traffic Counters
Disabling Default Features in IPv6 Multicast
Disabling Embedded RP Support in IPv6 PIM
Turning Off IPv6 PIM on a Specified Interface
Disabling MLD Router-Side Processing
Disabling MFIB Interrupt-Level IPv6 Multicast Forwarding
Troubleshooting IPv6 Multicast
Configuration Examples for IPv6 Multicast
Enabling IPv6 Multicast Routing: Example
Configuring PIM Options: Example
Configuring the MLD Protocol: Examples
Configuring Explicit Tracking of Receivers: Example
Configuring an IPv6 Multiprotocol BGP Peer Group: Example
Advertising Routes into IPv6 Multiprotocol BGP: Example
Redistributing Prefixes into IPv6 Multiprotocol BGP: Example
Generating Translate Updates for IPv6 Multicast BGP: Example
Turning Off IPv6 PIM on a Specified Interface: Example
Disabling MLD Router-Side Processing: Example
Feature Information for Implementing IPv6 Multicast
Implementing IPv6 Multicast
First Published: July 28, 2003Last Updated: June 25, 2009Traditional IP communication allows a host to send packets to a single host (unicast transmission) or to all hosts (broadcast transmission). IPv6 multicast provides a third scheme, allowing a host to send a single data stream to a subset of all hosts (group transmission) simultaneously.
This module describes the concepts and tasks you need to implement IPv6 multicast on your network.
Finding Feature Information
For the latest feature information and caveats, see the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the "Feature Information for Implementing IPv6 Multicast" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
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Prerequisites for IPv6 Multicast
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Prerequisites for IPv6 Multicast
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Restrictions for IPv6 Multicast
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Information About IPv6 Multicast
To configure IPv6 multicast, you need to understand the following concepts:
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IPv6 Multicast Overview
An IPv6 multicast group is an arbitrary group of receivers that want to receive a particular data stream. This group has no physical or geographical boundaries—receivers can be located anywhere on the Internet or in any private network. Receivers that are interested in receiving data flowing to a particular group must join the group by signaling their local router. This signaling is achieved with the MLD protocol.
Routers use the MLD protocol to learn whether members of a group are present on their directly attached subnets. Hosts join multicast groups by sending MLD report messages. The network then delivers data to a potentially unlimited number of receivers, using only one copy of the multicast data on each subnet. IPv6 hosts that wish to receive the traffic are known as group members.
Packets delivered to group members are identified by a single multicast group address. Multicast packets are delivered to a group using best-effort reliability, just like IPv6 unicast packets.
The multicast environment consists of senders and receivers. Any host, regardless of whether it is a member of a group, can send to a group. However, only the members of a group receive the message.
A multicast address is chosen for the receivers in a multicast group. Senders use that address as the destination address of a datagram to reach all members of the group.
Membership in a multicast group is dynamic; hosts can join and leave at any time. There is no restriction on the location or number of members in a multicast group. A host can be a member of more than one multicast group at a time.
How active a multicast group is, its duration, and its membership can vary from group to group and from time to time. A group that has members may have no activity.
IPv6 Multicast Addressing
An IPv6 multicast address is an IPv6 address that has a prefix of FF00::/8 (1111 1111). An IPv6 multicast address is an identifier for a set of interfaces that typically belong to different nodes. A packet sent to a multicast address is delivered to all interfaces identified by the multicast address. The second octet following the prefix defines the lifetime and scope of the multicast address. A permanent multicast address has a lifetime parameter equal to 0; a temporary multicast address has a lifetime parameter equal to 1. A multicast address that has the scope of a node, link, site, or organization, or a global scope has a scope parameter of 1, 2, 5, 8, or E, respectively. For example, a multicast address with the prefix FF02::/16 is a permanent multicast address with a link scope. Figure 1 shows the format of the IPv6 multicast address.
Figure 1 IPv6 Multicast Address Format
IPv6 nodes (hosts and routers) are required to join (receive packets destined for) the following multicast groups:
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IPv6 routers must also join the all-routers multicast group FF02:0:0:0:0:0:0:2 (scope is link-local).
The solicited-node multicast address is a multicast group that corresponds to an IPv6 unicast or anycast address. IPv6 nodes must join the associated solicited-node multicast group for every unicast and anycast address to which it is assigned. The IPv6 solicited-node multicast address has the prefix FF02:0:0:0:0:1:FF00:0000/104 concatenated with the 24 low-order bits of a corresponding IPv6 unicast or anycast address (see Figure 2). For example, the solicited-node multicast address corresponding to the IPv6 address 2037::01:800:200E:8C6C is FF02::1:FF0E:8C6C. Solicited-node addresses are used in neighbor solicitation messages.
Figure 2 IPv6 Solicited-Node Multicast Address Format
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IPv6 Multicast Groups
An IPv6 address must be configured on an interface for the interface to forward IPv6 traffic. Configuring a site-local or global IPv6 address on an interface automatically configures a link-local address and activates IPv6 for that interface. Additionally, the configured interface automatically joins the following required multicast groups for that link:
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For further information on configuring IPv6 addresses, refer to the Implementing IPv6 Addressing and Basic Connectivity module.
IPv6 Multicast Routing Implementation
The Cisco IOS XE software supports the following protocols to implement IPv6 multicast routing:
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Figure 3 shows where MLD and PIM-Sparse Mode (SM) operate within the IPv6 multicast environment.
Figure 3 IPv6 Multicast Routing Protocols Supported for IPv6
Multicast Listener Discovery Protocol for IPv6
To start implementing multicasting in the campus network, users must first define who receives the multicast. The MLD protocol is used by IPv6 routers to discover the presence of multicast listeners (for example, nodes that want to receive multicast packets) on their directly attached links, and to discover specifically which multicast addresses are of interest to those neighboring nodes. It is used for discovering local group and source-specific group membership. The MLD protocol provides a means to automatically control and limit the flow of multicast traffic throughout your network with the use of special multicast queriers and hosts.
The difference between multicast queriers and hosts is as follows:
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A set of queriers and hosts that receive multicast data streams from the same source is called a multicast group. Queriers and hosts use MLD reports to join and leave multicast groups and to begin receiving group traffic.
MLD uses the Internet Control Message Protocol (ICMP) to carry its messages. All MLD messages are link-local with a hop limit of 1, and they all have the router alert option set. The router alert option implies an implementation of the hop-by-hop option header.
MLD has three types of messages:
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Group-specific and multicast-address-specific queries are the same. A group address is a multicast address.
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MLD Access Group
The MLD access group provides receiver access control in Cisco IOS IPv6 multicast routers. This feature limits the list of groups a receiver can join, and it allows or denies sources used to join SSM channels.
Explicit Tracking of Receivers
The explicit tracking feature allows a router to track the behavior of the hosts within its IPv6 network. This feature also enables the fast leave mechanism to be used with MLD version 2 host reports.
Protocol Independent Multicast
Protocol Independent Multicast (PIM) is used between routers so that they can track which multicast packets to forward to each other and to their directly connected LANs. PIM works independently of the unicast routing protocol to perform send or receive multicast route updates like other protocols. Regardless of which unicast routing protocols are being used in the LAN to populate the unicast routing table, Cisco IOS XE PIM uses the existing unicast table content to perform the Reverse Path Forwarding (RPF) check instead of building and maintaining its own separate routing table.
PIM-Sparse Mode
IPv6 multicast provides support for intradomain multicast routing using PIM-SM. PIM-SM uses unicast routing to provide reverse-path information for multicast tree building, but it is not dependent on any particular unicast routing protocol.
PIM-SM is used in a multicast network when relatively few routers are involved in each multicast and these routers do not forward multicast packets for a group, unless there is an explicit request for the traffic. PIM-SM distributes information about active sources by forwarding data packets on the shared tree. PIM-SM initially uses shared trees, which requires the use of an RP.
Requests are accomplished via PIM joins, which are sent hop by hop toward the root node of the tree. The root node of a tree in PIM-SM is the RP in the case of a shared tree or the first-hop router that is directly connected to the multicast source in the case of a shortest path tree (SPT). The RP keeps track of multicast groups and the hosts that send multicast packets are registered with the RP by that host's first-hop router.
As a PIM join travels up the tree, routers along the path set up multicast forwarding state so that the requested multicast traffic will be forwarded back down the tree. When multicast traffic is no longer needed, a router sends a PIM prune up the tree toward the root node to prune (or remove) the unnecessary traffic. As this PIM prune travels hop by hop up the tree, each router updates its forwarding state appropriately. Ultimately, the forwarding state associated with a multicast group or source is removed.
A multicast data sender sends data destined for a multicast group. The designated router (DR) of the sender takes those data packets, unicast-encapsulates them, and sends them directly to the RP. The RP receives these encapsulated data packets, de-encapsulates them, and forwards them onto the shared tree. The packets then follow the (*, G) multicast tree state in the routers on the RP tree, at each point where the RP tree branches the packets are replicated and forwarded along the branches, eventually reaching all the receivers for that multicast group. The process of encapsulating data packets to the RP is called registering, and the encapsulation packets are called PIM register packets.
Designated Router
Cisco routers use PIM-SM to forward multicast traffic and follow an election process to select a designated router when more than one router is on a LAN segment.
The designated router is responsible for sending PIM register and PIM join and prune messages toward the RP to inform it about host group membership.
If multiple PIM-SM routers are on a LAN, a designated router must be elected to avoid duplicating multicast traffic for connected hosts. The PIM router with the highest IPv6 address becomes the DR for the LAN unless you choose to force the DR election by use of the ipv6 pim dr-priority command. This command allows you to specify the DR priority of each router on the LAN segment (default priority = 1) so that the router with the highest priority will be elected as the DR. If all routers on the LAN segment have the same priority, then the highest IPv6 address is again used as the tiebreaker.
Figure 4 illustrates what happens on a multiaccess segment. Router A and Router B are connected to a common multiaccess Gigabit Ethernet segment with Host A as an active receiver for Group A. Only Router A, operating as the DR, sends joins to the RP to construct the shared tree for Group A. If Router B was also permitted to send (*, G) joins to the RP, parallel paths would be created and Host A would receive duplicate multicast traffic. Once Host A begins to source multicast traffic to the group, the DR's responsibility is to send register messages to the RP. If both routers were assigned the responsibility, the RP would receive duplicate multicast packets.
Figure 4 Designated Router Election on a Multiaccess Segment
If the DR should fail, the PIM-SM provides a way to detect the failure of Router A and elect a failover DR. If the DR (Router A) became inoperable, Router B would detect this situation when its neighbor adjacency with Router A timed out. Because Router B has been hearing MLD membership reports from Host A, it already has MLD state for Group A on this interface and would immediately send a join to the RP when it became the new DR. This step reestablishes traffic flow down a new branch of the shared tree via Router B. Additionally, if Host A were sourcing traffic, Router B would initiate a new register process immediately after receiving the next multicast packet from Host A. This action would trigger the RP to join the SPT to Host A via a new branch through Router B.
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Rendezvous Point
IPv6 PIM provides embedded RP support. Embedded RP support allows the router to learn RP information using the multicast group destination address instead of the statically configured RP. For routers that are the RP, the router must be statically configured as the RP.
The router searches for embedded RP group addresses in MLD reports or PIM messages and data packets. On finding such an address, the router learns the RP for the group from the address itself. It then uses this learned RP for all protocol activity for the group. For routers that are the RP, the router is advertised as an embedded RP must be configured as the RP.
To select a static RP over an embedded RP, the specific embedded RP group range or mask must be configured in the access list of the static RP. When PIM is configured in sparse mode, you must also choose one or more routers to operate as an RP. An RP is a single common root placed at a chosen point of a shared distribution tree and is configured statically in each box.
PIM DRs forward data from directly connected multicast sources to the RP for distribution down the shared tree. Data is forwarded to the RP in one of two ways:
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The RP address is used by first-hop routers to send PIM register messages on behalf of a host sending a packet to the group. The RP address is also used by last-hop routers to send PIM join and prune messages to the RP to inform it about group membership. You must configure the RP address on all routers (including the RP router).
A PIM router can be an RP for more than one group. Only one RP address can be used at a time within a PIM domain for a certain group. The conditions specified by the access list determine for which groups the router is an RP.
IPv6 multicast supports the PIM accept register feature, which is the ability to perform PIM-SM register message filtering at the RP. The user can match an access list or compare the AS path for the registered source with the AS path specified in a route map.
IPv6 BSR
PIM routers in a domain must be able to map each multicast group to the correct RP address. The BSR protocol for PIM-SM provides a dynamic, adaptive mechanism to distribute group-to-RP mapping information rapidly throughout a domain. With the IPv6 BSR feature, if an RP becomes unreachable, it will be detected and the mapping tables will be modified so that the unreachable RP is no longer used, and the new tables will be rapidly distributed throughout the domain.
Every PIM-SM multicast group needs to be associated with the IP or IPv6 address of an RP. When a new multicast sender starts sending, its local DR will encapsulate these data packets in a PIM register message and send them to the RP for that multicast group. When a new multicast receiver joins, its local DR will send a PIM join message to the RP for that multicast group. When any PIM router sends a (*, G) join message, the PIM router needs to know which is the next router toward the RP so that the router can direct its (*, G) join message toward it. Also, when a PIM router is forwarding data packets using (*, G) state, the PIM router needs to know which is the correct incoming interface for packets destined for G, because it needs to reject any packets that arrive on other interfaces.
A small set of routers from a domain are configured as candidate bootstrap routers (C-BSRs) and a single BSR is selected for that domain. A set of routers within a domain are also configured as candidate RPs (C-RPs); typically, these routers are the same routers that are configured as C-BSRs. Candidate RPs periodically unicast candidate-RP-advertisement (C-RP-Adv) messages to the BSR of that domain, advertising their willingness to be an RP. A C-RP-Adv message includes the address of the advertising C-RP, and an optional list of group addresses and mask length fields, indicating the group prefixes for which the candidacy is advertised. The BSR then includes a set of these C-RPs, along with their corresponding group prefixes, in bootstrap messages (BSMs) it periodically originates. BSMs are distributed hop-by-hop throughout the domain.
The IPv6 BSR ability to configure RP mapping allows IPv6 multicast routers to be statically configured to announce scope-to-RP mappings directly from the BSR instead of learning them from candidate-RP messages. Announcing RP mappings from the BSR is useful in several situations:
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Cisco IOS IPv6 routers provide support for the RPF flooding of BSR packets so that a Cisco IOS IPv6 router will not disrupt the flow of BSMs. The router will recognize and parse enough of the BSM to identify the BSR address. The router performs an RPF check for this BSR address and forwards the packet only if it is received on the RPF interface. The router also creates a BSR entry containing RPF information to use for future BSMs from the same BSR. When BSMs from a given BSR are no longer received, the BSR entry is timed out.
Bidirectional BSR support allows bidirectional RPs to be advertised in C-RP messages and bidirectional ranges in the BSM. All routers in a system must be able to use the bidirectional range in the BSM; otherwise, the bidirectional RP feature will not function.
BSR provides scoped zone support by distributing group-to-RP mappings in networks using administratively scoped multicast. The user can configure candidate BSRs and a set of candidate RPs for each administratively scoped region in the user's domain.
For BSR to function correctly with administrative scoping, a BSR and at least one C-RP must be within every administratively scoped region. Administratively scoped zone boundaries must be configured at the zone border routers (ZBRs), because they need to filter PIM join messages that might inadvertently cross the border due to error conditions. In addition, at least one C-BSR within the administratively scoped zone must be configured to be a C-BSR for the administratively scoped zone's address range.
A separate BSR election will then take place (using BSMs) for every administratively scoped range, plus one for the global range. Administratively scoped ranges are identified in the BSM because the group range is marked to indicate that this is an administrative scope range, not just a range that a particular set of RPs is configured to handle.
Unless the C-RP is configured with a scope, it discovers the existence of the administratively scoped zone and its group range through reception of a BSM from the scope zone's elected BSR containing the scope zone's group range. A C-RP stores each elected BSR's address and the administratively scoped range contained in its BSM. It separately unicasts C-RP-Adv messages to the appropriate BSR for every administratively scoped range within which it is willing to serve as an RP.
All PIM routers within a PIM bootstrap domain where administratively scoped ranges are in use must be able to receive BSMs and store the winning BSR and RP set for all administratively scoped zones that apply.
PIM-Source Specific Multicast
PIM-SSM is the routing protocol that supports the implementation of SSM and is derived from PIM-SM. However, unlike PIM-SM where data from all multicast sources are sent when there is a PIM join, the SSM feature forwards datagram traffic to receivers from only those multicast sources that the receivers have explicitly joined, thus optimizing bandwidth utilization and denying unwanted Internet broadcast traffic. Further, instead of the use of RP and shared trees, SSM uses information found on source addresses for a multicast group. This information is provided by receivers through the source addresses relayed to the last-hop routers by MLD membership reports, resulting in resulting in shortest-path trees directly to the sources.
In SSM, delivery of datagrams is based on (S, G) channels. Traffic for one (S, G) channel consists of datagrams with an IPv6 unicast source address S and the multicast group address G as the IPv6 destination address. Systems will receive this traffic by becoming members of the (S, G) channel. Signaling is not required, but receivers must subscribe or unsubscribe to (S, G) channels to receive or not receive traffic from specific sources.
MLD version 2 is required for SSM to operate. MLD allows the host to provide source information. Before SSM will run with MLD, SSM must be supported in the Cisco IOS XE IPv6 router, the host where the application is running, and the application itself.
SSM Mapping for IPv6
SSM mapping for IPv6 supports both static and dynamic Domain Name System (DNS) mapping for MLD version 1 receivers. This feature allows deployment of IPv6 SSM with hosts that are incapable of providing MLD version 2 support in their TCP/IP host stack and their IP multicast receiving application.
SSM mapping allows the router to look up the source of a multicast MLD version 1 report either in the running configuration of the router or from a DNS server. The router can then initiate an (S, G) join toward the source.
PIM Shared Tree and Source Tree (Shortest-Path Tree)
By default, members of a group receive data from senders to the group across a single data distribution tree rooted at the RP. This type of distribution tree is called shared tree or rendezvous point tree (RPT), as illustrated in Figure 5. Data from senders is delivered to the RP for distribution to group members joined to the shared tree.
Figure 5 Shared Tree and Source Tree (Shortest Path Tree)
If the data threshold warrants, leaf routers on the shared tree may initiate a switch to the data distribution tree rooted at the source. This type of distribution tree is called a shortest path tree or source tree. By default, the Cisco IOS XE software switches to a source tree upon receiving the first data packet from a source.
The following process describes the move from shared tree to source tree in more detail:
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Join and prune messages are sent for sources and RPs. They are sent hop-by-hop and are processed by each PIM router along the path to the source or RP. Register and register-stop messages are not sent hop-by-hop. They are sent by the designated router that is directly connected to a source and are received by the RP for the group.
Reverse Path Forwarding
Reverse-path forwarding is used for forwarding multicast datagrams. It functions as follows:
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PIM uses both source trees and RP-rooted shared trees to forward datagrams; the RPF check is performed differently for each, as follows:
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Sparse-mode PIM uses the RPF lookup function to determine where it needs to send joins and prunes. (S, G) joins (which are source-tree states) are sent toward the source. (*, G) joins (which are shared-tree states) are sent toward the RP.
Routable Address Hello Option
When an IPv6 interior gateway protocol is used to build the unicast routing table, the procedure to detect the upstream router address assumes the address of a PIM neighbor is always same as the address of the next-hop router, as long as they refer to the same router. However, it may not be the case when a router has multiple addresses on a link.
Two typical situations can lead to this situation for IPv6. The first situation can occur when the unicast routing table is not built by an IPv6 interior gateway protocol such as multicast BGP. The second situation occurs when the address of an RP shares a subnet prefix with downstream routers (note that the RP router address has to be domain-wide and therefore cannot be a link-local address).
The routable address hello option allows the PIM protocol to avoid such situations by adding a PIM hello message option that includes all the addresses on the interface on which the PIM hello message is advertised. When a PIM router finds an upstream router for some address, the result of RPF calculation is compared with the addresses in this option, in addition to the PIM neighbor's address itself. Because this option includes all the possible addresses of a PIM router on that link, it always includes the RPF calculation result if it refers to the PIM router supporting this option.
Bidirectional PIM
Bidirectional PIM allows multicast routers to keep reduced state information, as compared with unidirectional shared trees in PIM-SM. Bidirectional shared trees convey data from sources to the RP and distribute them from the RP to the receivers. Unlike PIM-SM, bidirectional PIM does not switch over to the source tree, and there is no register encapsulation of data from the source to the RP.
Bidirectional PIM offers advantages when there are many moderate or low-rate sources. However, the bidirectional source trees have worse delay characteristics than do the source trees built in PIM-SM.
Only static configuration of bidirectional RPs is supported in IPv6.
Static Mroutes
IPv6 static mroutes behave much in the same way as do IPv6 static routes. IPv6 static mroutes share the same database as IPv6 static routes and are implemented by extending static route support. Static mroutes support equal-cost multipath mroutes, and they also support unicast-only static routes.
For further information on IPv6 static routes, see the Implementing Static Routes for IPv6 module.
MRIB
The Multicast Routing Information Base (MRIB) is a protocol-independent repository of multicast routing entries instantiated by multicast routing protocols (routing clients). Its main function is to provide independence between routing protocols and the Multicast Forwarding Information Base (MFIB). It also acts as a coordination and communication point among its clients.
Routing clients use the services provided by the MRIB to instantiate routing entries and retrieve changes made to routing entries by other clients. Besides routing clients, MRIB also has forwarding clients (MFIB instances) and special clients such as MLD. MFIB retrieves its forwarding entries from MRIB and notifies the MRIB of any events related to packet reception. These notifications can either be explicitly requested by routing clients or spontaneously generated by the MFIB.
Another important function of the MRIB is to allow for the coordination of multiple routing clients in establishing multicast connectivity within the same multicast session. MRIB also allows for the coordination between MLD and routing protocols.
MFIB
The MFIB is a platform-independent and routing-protocol-independent library for IPv6 software. Its main purpose is to provide a Cisco IOS XE platform with an interface with which to read the IPv6 multicast forwarding table and notifications when the forwarding table changes. The information provided by the MFIB has clearly defined forwarding semantics and is designed to make it easy for the platform to translate to its specific hardware or software forwarding mechanisms.
When routing or topology changes occur in the network, the IPv6 routing table is updated, and those changes are reflected in the MFIB. The MFIB maintains next-hop address information based on the information in the IPv6 routing table. Because there is a one-to-one correlation between MFIB entries and routing table entries, the MFIB contains all known routes and eliminates the need for route cache maintenance that is associated with switching paths such as fast switching and optimum switching.
Distributed MFIB
Distributed MFIB (dMFIB) is used to switch multicast IPv6 packets on distributed platforms. dMFIB may also contain platform-specific information on replication across line cards. The basic MFIB routines that implement the core of the forwarding logic are common to all forwarding environments.
dMFIB implements the following functionalities:
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The combination of dMFIB and MRIB subsystems also allows the router to have a "customized" copy of the MFIB database in each line card and to transport MFIB-related platform-specific information from the RP to the line cards.
IPv6 Multicast Process Switching and Fast Switching
A unified MFIB is used to provide both fast switching and process switching support for PIM-SM and PIM-SSM in IPv6 multicast. In process switching, the Route Processor must examine, rewrite, and forward each packet. The packet is first received and copied into the system memory. The router then looks up the Layer 3 network address in the routing table. The Layer 2 frame is then rewritten with the next-hop destination address and sent to the outgoing interface. The RP also computes the cyclic redundancy check (CRC). This switching method is the least scalable method for switching IPv6 packets.
IPv6 multicast fast switching allows routers to provide better packet forwarding performance than process switching. Information conventionally stored in a route cache is stored in several data structures for IPv6 multicast switching. The data structures provide optimized lookup for efficient packet forwarding.
In IPv6 multicast forwarding, the first packet is fast-switched if the PIM protocol logic allows it. In IPv6 multicast fast switching, the MAC encapsulation header is precomputed. IPv6 multicast fast switching uses the MFIB to make IPv6 destination prefix-based switching decisions. In addition to the MFIB, IPv6 multicast fast switching uses adjacency tables to prepend Layer 2 addressing information. The adjacency table maintains Layer 2 next-hop addresses for all MFIB entries.
The adjacency table is populated as adjacencies are discovered. Each time an adjacency entry is created (such as through ARP), a link-layer header for that adjacent node is precomputed and stored in the adjacency table. Once a route is determined, it points to a next hop and corresponding adjacency entry. It is subsequently used for encapsulation during switching of packets.
A route might have several paths to a destination prefix, such as when a router is configured for simultaneous load balancing and redundancy. For each resolved path, a pointer is added for the adjacency corresponding to the next-hop interface for that path. This mechanism is used for load balancing across several paths.
Multiprotocol BGP for the IPv6 Multicast Address Family
The multicast BGP for the IPv6 multicast address family feature provides multicast BGP extensions for IPv6 and supports the same features and functionality as IPv4 BGP. IPv6 enhancements to multicast BGP include support for an IPv6 multicast address family and network layer reachability information (NLRI) and next hop (the next router in the path to the destination) attributes that use IPv6 addresses.
Multicast BGP is an enhanced BGP that allows the deployment of interdomain IPv6 multicast. Multicast BGP carries routing information for multiple network layer protocol address families; for example, IPv6 address family and for IPv6 multicast routes. The IPv6 multicast address family contains routes used for RPF lookup by the IPv6 PIM protocol, and multicast BGP IPv6 provides for interdomain transport of the same. Users must use multicast BGP for IPv6 multicast when using IPv6 multicast with BGP because the unicast multicast BGP learned routes will not be used for IPv6 multicast.
Multicast BGP functionality provided through a separate address family context. A subsequent address family identifier (SAFI) provides information about the type of the network layer reachability information that is carried in the attribute. Multiprotocol BGP unicast uses SAFI 1 messages, and multiprotocol BGP multicast uses SAFI 2 messages.
A separate BGP routing table is maintained to configure incongruent policies and topologies (for example, IPv6 unicast and multicast) by using IPv6 multicast RPF lookup. Multicast RPF lookup is very similar to the IP unicast route lookup.
No MRIB is associated with the IPv6 multicast BGP table. However, IPv6 multicast BGP operates on the unicast IPv6 RIB when needed. Multicast BGP does not insert or update routes into the IPv6 unicast RIB.
How to Implement IPv6 Multicast
The tasks in the following sections explain how to implement IPv6 multicast:
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Enabling IPv6 Multicast Routing
This task explains how to enable IPv6 multicast routing on all interfaces and to enable multicast forwarding for PIM and MLD on all enabled interfaces of the router.
Prerequisites
In order to enable IPv6 multicast routing on a router, you must first enable IPv6 unicast routing on the router. For information on how to enable IPv6 unicast routing on a router, refer to the Implementing IPv6 Addressing and Basic Connectivity module.
If you are already using an IPv6 unicast router, use the following tasks to enable IPv6 multicast routing and configure IPv6 multicast routing options.
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Configuring the MLD Protocol
The following tasks describe how to customize and verify the MLD protocol.
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Customizing and Verifying MLD on an Interface
Use the following commands to customize MLD and verify MLD information on each interface, if desired.
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Implementing MLD Group Limits
Per-interface and global MLD limits operate independently of each other. Both per-interface and global MLD limits can be configured on the same router. The number of MLD limits, globally or per interface, is not configured by default; the limits must be configured by the user. A membership report that exceeds either the per-interface or the global state limit is ignored.
The following tasks describe how to limit MLD states that result from MLD version 2 or MLD version 1 membership reports globally or per interface:
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Implementing MLD Group Limits Globally
This task describes how to limit MLD groups globally.
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Implementing MLD Group Limits per Interface
This task describes how to limit MLD groups on a per-interface basis.
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Configuring Explicit Tracking of Receivers to Track Host Behavior
This task enables the explicit tracking of receivers feature. The explicit tracking feature allows a router to track the behavior of the hosts within its IPv6 network and enables the fast leave mechanism to be used with MLD version 2 host reports.
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Resetting the MLD Traffic Counters
This task explains how to reset the MLD traffic counters and verify MLD traffic information.
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Clearing the MLD Interface Counters
This task explains how to clear MLD interface counters.
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Configuring PIM
The following tasks explain how to configure PIM and display PIM configuration and information.
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Configuring PIM Options
The following task explains commands you can use to refine your configuration for PIM-SSM, both in general or on specified interfaces. The task also gives various commands that can be used to verify PIM configuration and information.
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Configuring Bidirectional PIM and Displaying Bidirectional PIM Information
This task explains how to configure bidirectional PIM and use show commands to display bidirectional PIM information.
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Resetting the PIM Traffic Counters
If PIM malfunctions or in order to verify that the expected number of PIM packets are received and sent, the user can clear PIM traffic counters. Once the traffic counters are cleared, the user can enter the show ipv6 pim traffic command to verify that PIM is functioning correctly and that PIM packets are being received and sent correctly.
This task explains how to reset the PIM traffic counters and verify PIM traffic information.
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Clearing the PIM Topology Table to Reset the MRIB Connection
No configuration is necessary to use the MRIB. However, users may in certain situations want to clear the PIM topology table in order to reset the MRIB connection, and verify MRIB information.
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Configuring a BSR
The following tasks explains how to perform BSR configuration and to verify BSR configuration and information:
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Configuring a BSR and Verifying BSR Information
This task describes how to configure a BSR on a specified interface and verify BSR configuration information.
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Configuring to send PIM RP Advertisements to the BSR
This task explains how to configure a router to send PIM RP advertisements to the BSR.
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Configuring SSM Mapping
When the SSM mapping feature is enabled, DNS-based SSM mapping is automatically enabled, which means that the router will look up the source of a multicast MLD version 1 report from a DNS server.
You can use either DNS-based or static SSM mapping, depending on your router configuration. If you choose to use static SSM mapping, you can configure multiple static SSM mappings. If multiple static SSM mappings are configured, the source addresses of all matching access lists will be used.
This task explains how to enable SSM mapping, disable DNS-based mapping, and configure static SSM mapping.
Restrictions
To use DNS-based SSM mapping, the router needs to find at least one correctly configured DNS server, to which the router may be directly attached.
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Configuring Static Mroutes
This task explains how to configure a static multicast route and verify static mroute information. Static multicast routes (mroutes) in IPv6 can be implemented as an extension of IPv6 static routes. You can configure your router to use a static route for unicast routing only, to use a static multicast route for multicast RPF selection only, or to use a static route for both unicast routing and multicast RPF selection.
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Configuring IPv6 Multiprotocol BGP
The following tasks explain how to configure IPv6 multiprotocol BGP to perform multicast routing. Note that these multicast BGP tasks related to IPv6 multicast are similar to those multicast BGP tasks for IPv6 unicast.
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Configuring an IPv6 Peer Group to Perform Multicast BGP Routing
The following tasks explain how to configure an IPv6 peer group to perform multicast BGP routing.
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What to Do Next
Refer to the section "Configuring an IPv6 Multiprotocol BGP Peer Group" in the Implementing Multiprotocol BGP for IPv6 module and the "Configure BGP Peer Groups" section of the "Configuring BGP" chapter in the Cisco IOS XE IP Routing Configuration Guide, for more information on assigning options to peer groups and making a BGP or multicast BGP neighbor a member of a peer group.
Advertising Routes into IPv6 Multiprotocol BGP
This task explains how to advertise (inject) a prefix into IPv6 multicast BGP. Note that this task and other multicast BGP tasks related to IPv6 multicast are similar to those multicast BGP tasks for IPv6 unicast.
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What to Do Next
Refer to the section "Advertising Routes into IPv6 Multiprotocol BGP" in the Implementing Multiprotocol BGP for IPv6 module for more information on assigning options to peer groups and making a BGP or multicast BGP neighbor a member of a peer group.
Redistributing Prefixes into IPv6 Multiprotocol BGP
This task explains how to redistribute (inject) prefixes from another routing protocol into IPv6 multicast BGP. Note that this task and other multicast BGP tasks related to IPv6 multicast are similar to those multicast BGP tasks for IPv6 unicast.
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What to Do Next
Refer to the section "Redistributing Prefixes into IPv6 Multiprotocol BGP" in the Implementing Multiprotocol BGP for IPv6 module for more information on assigning options to peer groups and making a BGP or multicast BGP neighbor a member of a peer group.
Configuring Aggregate Addresses
To configure aggregate addresses for Multicast BGP, refer to the "Configuring Aggregate Addresses" section of the "Configuring BGP" chapter in the Cisco IOS XE IP Routing Configuration Guide.
Assigning a BGP Administrative Distance
This task explains how to specify an administrative distance for multicast BGP routes to be used in RPF lookups for comparison with unicast routes. Please note that this task and other multicast BGP tasks related to IPv6 multicast are similar to those multicast BGP tasks for IPv6 unicast.
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Generating Translate Updates for IPv6 Multicast BGP
This task explains how to generate IPv6 multicast BGP updates that correspond to unicast IPv6 updates received from a peer.
The multicast BGP translate-update feature generally is used in an multicast BGP-capable router that peers with a customer site that has only a BGP-capable router; the customer site has not or cannot upgrade its router to an multicast BGP-capable image. Because the customer site cannot originate multicast BGP advertisements, the router with which it peers will translate the BGP prefixes into multicast BGP prefixes, which are used for multicast-source RPF lookup.
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Resetting BGP Sessions
This task explains how to reset IPv6 BGP sessions.
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Clearing External BGP Peers
This task explains how to clear external BGP peers and members of an IPv6 BGP peer group.
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Clearing IPv6 BGP Route Dampening Information
This task explains how to clear IPv6 BGP route dampening information and how to unsuppress suppressed routes.
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Clearing IPv6 BGP Flap Statistics
This task explains how to clear IPv6 BGP flap statistics.
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Using MFIB in IPv6 Multicast
Multicast forwarding is automatically enabled when IPv6 multicast routing is enabled. The following tasks explain how to display information to verify MFIB configuration and operation and reset MFIB as needed.
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Verifying MFIB Operation in IPv6 Multicast
This task explains how to display and verify MFIB use in IPv6 multicast.
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Resetting MFIB Traffic Counters
This task explains how to reset all active MFIB traffic counters.
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Disabling Default Features in IPv6 Multicast
Several features are automatically enabled when IPv6 multicast is used. However, a user may want to disable certain features in response to certain situations. The following tasks describe these situations and how to disable specific IPv6 multicast features.
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Disabling Embedded RP Support in IPv6 PIM
A user might want to disable embedded RP support on an interface if all of the routers in the domain do not support embedded RP. This task explains how to disable embedded RP support in IPv6 PIM.
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Turning Off IPv6 PIM on a Specified Interface
A user might only want specified interfaces to perform IPv6 multicast and will therefore want to turn off PIM on a specified interface. This task explains how to turn off PIM on a specified interface.
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Disabling MLD Router-Side Processing
A user might only want specified interfaces to perform IPv6 multicast and will therefore want to turn off MLD router-side processing on a specified interface. Use the following task to disable MLD router-side processing on a specified interface.
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Disabling MFIB on the Router
Multicast forwarding is automatically enabled when IPv6 multicast routing is enabled. However, a user may want to disable multicast forwarding on the router. The following task explains how to disable multicast forwarding on the router:
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Disabling MFIB Interrupt-Level IPv6 Multicast Forwarding
MFIB interrupt-level IPv6 multicast forwarding of outgoing packets on a specific interface is enabled on interfaces that support Cisco Express Forwarding. However, a user may want to disable MFIB interrupt-level forwarding on a specified interface. The following task explains how to disable this feature:
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Troubleshooting IPv6 Multicast
Use debug commands to help you troubleshoot an IPv6 multicast environment. This task describes the commands to display debugging information on IPv6 multicast.
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Examples
This section provides the following output examples:
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Sample Output from the show ipv6 mfib Command
The following example displays the forwarding entries and interfaces in the MFIB. The router is configured for fast switching, and it has a receiver joined to FF05::1 on GigabitEthernet 1/1/0 and a source (2001:0DB8:1:1:20) sending on GigabitEthernet 1/2/0:
Router# show ipv6 mfibIP Multicast Forwarding Information BaseEntry Flags: C - Directly Connected, S - Signal, IA - Inherit A flag,AR - Activity Required, D - DropForwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kbits per secondOther counts: Total/RPF failed/Other dropsInterface Flags: A - Accept, F - Forward, NS - Negate SignallingIC - Internal Copy, NP - Not platform switchedSP - Signal PresentInterface Counts: FS Pkt Count/PS Pkt Count(*,FF00::/8) Flags: CForwarding: 0/0/0/0, Other: 0/0/0Tunnel0 Flags: NS(*,FF00::/15) Flags: DForwarding: 0/0/0/0, Other: 0/0/0(*,FF05::1) Flags: CForwarding: 2/0/100/0, Other: 0/0/0Tunnel0 Flags: A NSGigabitEthernet1/1/0 Flags: F NSPkts: 0/2(2001:0DB8:1:1:200,FF05::1) Flags:Forwarding: 5/0/100/0, Other: 0/0/0GigabitEthernet1/2/0 Flags: AGigabitEthernet1/1/0 Flags: F NSPkts: 3/2(*,FF10::/15) Flags: DForwarding: 0/0/0/0, Other: 0/0/0Sample Output from the show ipv6 mfib active Command
The following example displays statistics on the rate at which active IP multicast sources are sending information. The router is switching traffic from 2001:0DB8:1:1:200 to FF05::1:
Router# show ipv6 mfib activeActive IPv6 Multicast Sources - sending >= 4 kbpsGroup: FF05::1Source: 2001:0DB8:1:1:200Rate: 20 pps/16 kbps(1sec), 0 kbps(last 128 sec)Sample Output from the show ipv6 mfib count Command
The following example displays statistics from the MFIB about the group and source. The router is switching traffic from 2001:0DB8:1:1:200 to FF05::1:
Router# show ipv6 mfib countIP Multicast Statistics54 routes, 7 groups, 0.14 average sources per groupForwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per secondOther counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)Group: FF00::/8RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0Group: FF00::/15RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0Group: FF05::1RP-tree: Forwarding: 2/0/100/0, Other: 0/0/0Source: 10::1:1:200, Forwarding: 367/10/100/7, Other: 0/0/0Tot. shown: Source count: 1, pkt count: 369Group: FF10::/15RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0Group: FF20::/15RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0Sample Output from the show ipv6 mfib interface Command
The following example displays information about IPv6 multicast-enabled interfaces and their forwarding status. The router is configured for fast switching:
Router# show ipv6 mfib interfaceIPv6 Multicast Forwarding (MFIB) status:Configuration Status: enabledOperational Status: runningMFIB interface status CEF-based output[configured,available]GigabitEthernet1/1/0 up [yes ,yes ]GigabitEthernet1/2/0 up [yes ,? ]Tunnel0 up [yes ,? ]Tunnel1 up [yes ,? ]Sample Output from the show ipv6 mfib summary Command
The following example displays summary information about the number of IPv6 MFIB entries and interfaces:
Router# show ipv6 mfib summaryIPv6 MFIB summary:54 total entries [1 (S,G), 7 (*,G), 46 (*,G/m)]17 total MFIB interfacesSample Output from the show ipv6 mld groups Command
The following is sample output from the show ipv6 mld groups command. It shows all of the groups joined by Gigabit Ethernet interface 2/1/0, including link-local groups used by network protocols.
Router# show ipv6 mld groups GigabitEthernet 2/1/0MLD Connected Group MembershipGroup Address Interface Uptime ExpiresFF02::2 GigabitEthernet2/1/0 3d18h neverFF02::D GigabitEthernet2/1/0 3d18h neverFF02::16 GigabitEthernet2/1/0 3d18h neverFF02::1:FF00:1 GigabitEthernet2/1/0 3d18h 00:00:27FF02::1:FF00:79 GigabitEthernet2/1/0 3d18h neverFF02::1:FF23:83C2 GigabitEthernet2/1/0 3d18h 00:00:22FF02::1:FFAF:2C39 GigabitEthernet2/1/0 3d18h neverFF06:7777::1 GigabitEthernet2/1/0 3d18h 00:00:26Sample Output from the show ipv6 mld groups summary Command
The following is sample output from the show ipv6 mld groups summary command:
Router# show ipv6 mld groups summaryMLD Route SummaryNo. of (*,G) routes = 5No. of (S,G) routes = 0Sample Output from the show ipv6 mld interface Command
The following is sample output from the show ipv6 mld interface command for Gigabit Ethernet interface 2/1/0:
Router# show ipv6 mld interface GigabitEthernet 2/1/0GigabitEthernet2/1/0 is up, line protocol is upInternet address is FE80::205:5FFF:FEAF:2C39/10MLD is enabled in interfaceCurrent MLD version is 2MLD query interval is 125 secondsMLD querier timeout is 255 secondsMLD max query response time is 10 secondsLast member query response interval is 1 secondsMLD activity: 25 joins, 17 leavesMLD querying router is FE80::205:5FFF:FEAF:2C39 (this system)Sample Output from the show ipv6 mld ssm-map Command
The following examples show SSM mapping for the source address 2001:0DB8::1:
Router# show ipv6 mld ssm-map 2001:0DB8::1Group address : 2001:0DB8::1Group mode ssm : TRUEDatabase : STATICSource list : 2001:0DB8::22001:0DB8::3Router# show ipv6 mld ssm-map 2001:0DB8::2Group address : 2001:0DB8::2Group mode ssm : TRUEDatabase : DNSSource list : 2001:0DB8::32001:0DB8::1Sample Output from the show ipv6 mld traffic Command
The following example displays the MLD protocol messages received and sent.
Router# show ipv6 mld trafficMLD Traffic CountersElapsed time since counters cleared:00:00:21Received SentValid MLD Packets 3 1Queries 1 0Reports 2 1Leaves 0 0Mtrace packets 0 0Errors:Malformed Packets 0Bad Checksums 0Martian source 0Packets Received on MLD-disabled Interface 0Sample Output from the show ipv6 mrib client Command
The following is sample output from the show ipv6 mrib client command:
Router# show ipv6 mrib clientIP MRIB client-connectionsigmp:145 (connection id 0)pim:146 (connection id 1)mfib ipv6:3 (connection id 2)slot 3 mfib ipv6 rp agent:16 (connection id 3)slot 1 mfib ipv6 rp agent:16 (connection id 4)slot 0 mfib ipv6 rp agent:16 (connection id 5)slot 4 mfib ipv6 rp agent:16 (connection id 6)slot 2 mfib ipv6 rp agent:16 (connection id 7)Sample Output from the show ipv6 mrib route Command
The following is sample output from the show ipv6 mrib route command using the summary keyword:
Router# show ipv6 mrib route summaryMRIB Route-DB SummaryNo. of (*,G) routes = 52No. of (S,G) routes = 0No. of Route x Interfaces (RxI) = 10Sample Output from the show ipv6 mroute Command
Using the show ipv6 mroute command is a good way to dynamically verify that multicast IPv6 data is flowing. The following is sample output from the show ipv6 mroute command:
Router# show ipv6 mroute ff07::1Multicast Routing TableFlags:D - Dense, S - Sparse, B - Bidir Group, s - SSM Group,C - Connected, L - Local, I - Received Source Specific Host Report,P - Pruned, R - RP-bit set, F - Register flag, T - SPT-bit set,J - Join SPTTimers:Uptime/ExpiresInterface state:Interface, State(*, FF07::1), 00:04:45/00:02:47, RP 2001:0DB8:6::6, flags:SIncoming interface:Tunnel5RPF nbr:6:6:6::6Outgoing interface list:POS4/0, Forward, 00:04:45/00:02:47(2001:0DB8:999::99, FF07::1), 00:02:06/00:01:23, flags:SFTIncoming interface:POS1/0RPF nbr:2001:0DB8:999::99Outgoing interface list:POS4/0, Forward, 00:02:06/00:03:27Sample Output from the show ipv6 mroute active Command
The following is sample output from the show ipv6 mroute active command:
Router# show ipv6 mroute activeActive IPv6 Multicast Sources - sending >= 4 kbpsGroup:FF05::1Source:2001:0DB8:1:1:1Rate:11 pps/8 kbps(1sec), 8 kbps(last 8 sec)Sample Output from the show ipv6 pim group-map Command
The following is sample output from the show ipv6 pim group-map command:
Router# show ipv6 pim group-mapFF33::/32*SSMInfo source:StaticUptime:00:08:32, Groups:0FF34::/32*SSMInfo source:StaticUptime:00:09:42, Groups:0Sample Output from the show ipv6 pim interface Command
The following is sample output from the show ipv6 pim interface command using the state-on keyword:
Router# show ipv6 pim interface state-onInterface PIM Nbr Hello DRCount Intvl PriorGigabitEthernet0/0/0 on 0 30 1Address:FE80::208:20FF:FE08:D7FFDR :this systemPOS1/0 on 0 30 1Address:FE80::208:20FF:FE08:D554DR :this systemPOS4/0 on 1 30 1Address:FE80::208:20FF:FE08:D554DR :FE80::250:E2FF:FE8B:4C80POS4/1 on 0 30 1Address:FE80::208:20FF:FE08:D554DR :this systemLoopback0 on 0 30 1Address:FE80::208:20FF:FE08:D554DR :this systemSample Output from the show ipv6 pim join-prune statistic Command
The following example provides the join/prune aggregation on GigabitEthernet interface 0/0/0:
Router# show ipv6 pim join-prune statistic GigabitEthernet0/0/0PIM Average Join/Prune Aggregation for last (1K/10K/50K) packetsInterface Transmitted ReceivedGigabitEthernet0/0/0 0 / 0 / 0 1 / 0 / 0Sample Output from the show ipv6 pim range-list Command
The following is sample output from the show ipv6 pim range-list command:
Router# show ipv6 pim range-listconfig SSM Exp:never Learnt from :::FF33::/32 Up:00:26:33FF34::/32 Up:00:26:33FF35::/32 Up:00:26:33FF36::/32 Up:00:26:33FF37::/32 Up:00:26:33FF38::/32 Up:00:26:33FF39::/32 Up:00:26:33FF3A::/32 Up:00:26:33FF3B::/32 Up:00:26:33FF3C::/32 Up:00:26:33FF3D::/32 Up:00:26:33FF3E::/32 Up:00:26:33FF3F::/32 Up:00:26:33config SM RP:40::1:1:1 Exp:never Learnt from :::FF13::/64 Up:00:03:50config SM RP:40::1:1:3 Exp:never Learnt from :::FF09::/64 Up:00:03:50Sample Output from the show ipv6 pim topology Command
The following is sample output from the show ipv6 pim topology command:
Router# show ipv6 pim topologyIP PIM Multicast Topology TableEntry state:(*/S,G)[RPT/SPT] Protocol Uptime InfoEntry flags:KAT - Keep Alive Timer, AA - Assume Alive, PA - Probe Alive,RA - Really Alive, LH - Last Hop, DSS - Don't Signal Sources,RR - Register Received, SR - Sending Registers, E - MSDP External,DCC - Don't Check ConnectedInterface state:Name, Uptime, Fwd, InfoInterface flags:LI - Local Interest, LD - Local Dissinterest,II - Internal Interest, ID - Internal Dissinterest,LH - Last Hop, AS - Assert, AB - Admin Boundary(*,FF05::1)SM UP:02:26:56 JP:Join(now) Flags:LHRP:2001:0DB8:1:1:2RPF:GigabitEthernet1/1/0,FE81::1GigabitEthernet0/1/0 02:26:56 fwd LI LH(2001:0DB8:1:1:200,FF05::1)SM UP:00:00:07 JP:Null(never) Flags:RPF:GigabitEthernet1/1/0,FE80::30:1:4GigabitEthernet1/1/0 00:00:07 off LISample Output from the show ipv6 pim traffic Command
The following example shows the number of PIM protocol messages received and sent.
Router# show ipv6 pim trafficPIM Traffic CountersElapsed time since counters cleared:00:05:29Received SentValid PIM Packets 22 22Hello 22 22Join-Prune 0 0Register 0 0Register Stop 0 0Assert 0 0Bidir DF Election 0 0Errors:Malformed Packets 0Bad Checksums 0Send Errors 0Packet Sent on Loopback Errors 0Packets Received on PIM-disabled Interface 0Packets Received with Unknown PIM Version 0Sample Output from the show ipv6 pim tunnel Command
The following is sample output from the show ipv6 pim tunnel command on the RP:
Router# show ipv6 pim tunnelTunnel0*Type :PIM EncapRP :100::1Source:100::1Tunnel0*Type :PIM DecapRP :100::1Source: -The following is sample output from the show ipv6 pim tunnel command on a non-RP:
Router# show ipv6 pim tunnelTunnel0*Type :PIM EncapRP :100::1Source:2001::1:1:1Sample Output from the show ipv6 rpf Command
The following example displays RPF information for the unicast host with the IPv6 address of 2001:0DB8:1:1:2:
Router# show ipv6 rpf 2001:0DB8:1:1:2RPF information for 2001:0DB8:1:1:2RPF interface:GigabitEthernet3/2/0RPF neighbor:FE80::40:1:3RPF route/mask:20::/64RPF type:UnicastRPF recursion count:0Metric preference:110Metric:30Configuration Examples for IPv6 Multicast
This section provides the following configuration examples:
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Enabling IPv6 Multicast Routing: Example
The following example enables multicast routing on all interfaces. Entering this command also enables multicast forwarding for PIM and MLD on all enabled interfaces of the router.
Router> enableRouter# configure terminalRouter(config)# ipv6 multicast-routing
Configuring PIM: Examples
The following example shows how to configure a router to use PIM-SM using 20010DB8::1 as the RP. The following example sets the SPT threshold to infinity to prevent switchover to the source tree when a source starts sending traffic and sets a filter on all sources that do not have a local multicast BGP prefix.
Router(config)# ipv6 multicast-routingRouter(config)# ipv6 pim rp-address 2001:0DB8::1Router(config)# ipv6 pim spt-threshold infinityConfiguring PIM Options: Example
The following example sets the DR priority, sets the PIM hello interval, and sets the periodic join and prune announcement interval on GigabitEthernet interface 0/0/0.
Router(config)# interface GigabitEthernet0/0/0Router(config)# ipv6 pim hello-interval 60Router(config)# ipv6 pim dr-priority 3Router(config)# ipv6 pim join-prune-interval 75Configuring the MLD Protocol: Examples
The following example shows how to configure the query maximum response time, the query timeout, and the query interval on GigabitEthernet interface 1/0/0:
Router> enableRouter# configure terminalRouter(config)# interface GigabitEthernet 1/0/0Router(config-if)# ipv6 mld query-max-response-time 20
Router(config-if)# ipv6 mld query-timeout 130
Router(config-if)# ipv6 mld query-interval 60
The following example configures MLD reporting for a specified group and source, allows the user to perform IPv6 multicast receiver access control, and statically forwards traffic for the multicast group onto GigabitEthernet interface 1/0/0:
Router> enableRouter# configure terminalRouter(config)# interface GigabitEthernet 1/0/0Router(config)# ipv6 mld join-group FF04::10Router(config)# ipv6 mld static-group FF04::10 100::1Router(config)# ipv6 mld access-group acc-grp-1Configuring Explicit Tracking of Receivers: Example
The following example shows how to configure the explicit tracking of receivers:
Router> enableRouter# configure terminalRouter(config)# interface GigabitEthernet 1/0/0Router(config-if)# ipv6 mld explicit-tracking list1Configuring Mroutes: Example
The following example shows how to configure a static multicast route to be used for multicast RPF selection only.
Router> enableRouter# configure terminalRouter(config)# ipv6 route 2001:0DB8::/64 7::7 100 multicastConfiguring an IPv6 Multiprotocol BGP Peer Group: Example
The following example configures the IPv6 multiprotocol BGP peer group named group1:
router bgp 65000no bgp default ipv4-unicastneighbor group1 peer-groupneighbor 2001:0DB8:0:CC00::1 remote-as 64600address-family ipv6 multicastneighbor 3FFE:C00:0:1:A8BB:CCFF:FE00:8200 activateno auto-summaryno synchronizationexit-address-familyAdvertising Routes into IPv6 Multiprotocol BGP: Example
The following example injects the IPv6 network 2001:0DB8::/24 into the IPv6 multicast database of the local router. (BGP checks that a route for the network exists in the IPv6 multicast database of the local router before advertising the network.)
router bgp 65000no bgp default ipv4-unicastaddress-family ipv6 multicastnetwork 2001:0DB8::/24Redistributing Prefixes into IPv6 Multiprotocol BGP: Example
The following example redistributes BGP routes into the IPv6 multicast database of the local router:
router bgp 64900no bgp default ipv4-unicastaddress-family ipv6 multicastredistribute BGPGenerating Translate Updates for IPv6 Multicast BGP: Example
The following example shows how to generate IPv6 multicast BGP updates that correspond to unicast IPv6 updates:
router bgp 64900no bgp default ipv4-unicastaddress-family ipv6 multicastneighbor 2001:0DB8:7000::2 translate-update ipv6 multicastTurning Off IPv6 PIM on a Specified Interface: Example
The following example turns off IPv6 PIM on GigabitEthernet interface 1/0/0:
Router(config)# ipv6 multicast-routingRouter(config)# interface GigabitEthernet 1/0/0Router(config)# no ipv6 pimDisabling MLD Router-Side Processing: Example
The following example turns off MLD router-side processing on GigabitEthernet interface 1/0/0:
Router> enableRouter# configure terminalRouter(config)# interface GigabitEthernet 1/0/0Router(config-if)# no ipv6 mld router
Additional References
The following sections provide references related to the Implementing IPv6 Multicast feature.
Related Documents
IPv6 multicast addresses
Implementing IPv6 Addressing and Basic Connectivity, Cisco IOS XE IPv6 Configuration Guide
IPv6 supported feature list
Start Here: Cisco IOS Software Release Specifics for IPv6 Features, Cisco IOS XE IPv6 Configuration Guide
Multicast BGP for IPv6
Implementing Multiprotocol BGP for IPv6, Cisco IOS XE IPv6 Configuration Guide
IPv6 static routes
Implementing Static Routes for IPv6, Cisco IOS XE IPv6 Configuration Guide
IPv6 tunnels
Implementing Tunneling for IPv6, Cisco IOS XE IPv6 Configuration Guide
IPv6 commands: complete command syntax, command mode, defaults, usage guidelines, and examples
IPv4 command reference
Cisco IOS master command list, all releases
Standards and Drafts
MIBs
RFCs
Technical Assistance
Feature Information for Implementing IPv6 Multicast
Table 1 lists the features in this module and provides links to specific configuration information.
For information on a feature in this technology that is not documented here, see Start Here: Cisco IOS XE Software Release Specifics for IPv6 Features.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note
Table 1 Feature Information for Implementing IPv6 Multicast
IPv6 Multicast
Cisco IOS XE Release 2.1
IPv6 multicast allows a host to send a single data stream to a subset of all hosts simultaneously.
This entire document provides information about this feature.
IPv6 multicast: Multicast Listener Discovery (MLD) protocol, versions 1 and 2
Cisco IOS XE Release 2.1
MLD is used by IPv6 routers to discover multicast listeners (nodes that want to receive multicast packets destined for specific multicast addresses) on directly attached links. There are two versions of MLD: MLD version 1 is based on version 2 of the IGMP for IPv4, and MLD version 2 is based on version 3 of the IGMP for IPv4. IPv6 multicast for Cisco IOS XE software uses both MLD version 2 and MLD version 1.
The following sections provide information about this feature:
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The following commands were modified by this feature: clear ipv6 mld counters, clear ipv6 mld traffic, debug ipv6 mld, debug ipv6 mld explicit, debug ipv6 mld ssm-map, ipv6 mld join-group, ipv6 mld query-interval, ipv6 mld query-max-response-time, ipv6 mld query-timeout, ipv6 mld router, ipv6 mld static-group, ipv6 multicast-routing, show ipv6 mld interface, show ipv6 mld groups, show ipv6 mld groups summary, show ipv6 mld traffic
IPv6 multicast: PIM sparse mode (PIM-SM)
Cisco IOS XE Release 2.1
Cisco IOS XE Release 2.4PIM-SM uses unicast routing to provide reverse-path information for multicast tree building. PIM-SM is used in a multicast network when relatively few routers are involved in each multicast and these routers do not forward multicast packets for a group, unless there is an explicit request for the traffic.
The following sections provide information about this feature:
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IPv6 multicast: PIM Source Specific Multicast (PIM-SSM)
Cisco IOS XE Release 2.1
PIM-SSM supports the implementation of SSM and is derived from PIM-SM. The SSM feature forwards datagram traffic to receivers from only those multicast sources that the receivers have explicitly joined, optimizing bandwidth utilization and denying unwanted Internet broadcast traffic.
The following sections provide information about this feature:
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The following commands were modified by this feature: clear ipv6 pim counters, clear ipv6 pim topology, debug ipv6 pim, debug ipv6 pim df-election, ipv6 pim, ipv6 pim dr-priority, ipv6 pim hello-interval, ipv6 pim join-prune-interval, ipv6 pim spt-threshold infinity, show ipv6 mrib client, show ipv6 mrib route, show ipv6 pim group-map, show ipv6 pim interface, show ipv6 pim join-prune statistic, show ipv6 pim range-list, show ipv6 pim traffic, show ipv6 pim topology
IPv6 multicast: MLD access group
Cisco IOS XE Release 2.1
The MLD access group provides receiver access control in Cisco IOS XE IPv6 multicast routers.
The following sections provide information about this feature:
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The following command was modified by this feature: ipv6 mld access-group
IPv6 multicast: routable address hello option
Cisco IOS XE Release 2.1
Cisco IOS XE Release 2.4The routable address hello option adds a PIM hello message option that includes all the addresses on the interface on which the PIM hello message is advertised.
The following sections provide information about this feature:
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IPv6 multicast: static multicast routing (mroute)
Cisco IOS XE Release 2.1
IPv6 static mroutes share the same database as IPv6 static routes and are implemented by extending static route support.
The following sections provide information about this feature:
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The following commands were modified by this feature: ipv6 route, show ipv6 mroute, show ipv6 mroute active, show ipv6 rpf
IPv6 multicast: address family support for multiprotocol BGP
Cisco IOS XE Release 2.1
This feature provides multicast BGP extensions for IPv6 and supports the same features and functionality as IPv4 BGP.
The following sections provide information about this feature:
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IPv6 multicast: explicit tracking of receivers
Cisco IOS XE Release 2.1
This feature allows a router to track the behavior of the hosts within its IPv6 network.
The following sections provide information about this feature:
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The following command was modified by this feature: ipv6 mld explicit-tracking
IPv6 multicast: IPv6 bidirectional PIM
Cisco IOS XE Release 2.3
Bidirectional PIM allows multicast routers to keep reduced state information. Bidirectional shared trees convey data from sources to the RP and distribute them from the RP to the receivers.
The following sections provide information about this feature:
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The following commands were modified by this feature: ipv6 pim rp-address, show ipv6 pim df, show ipv6 pim df winner
IPv6 Multicast: Bootstrap Router (BSR)
Cisco IOS XE Release 2.1
Cisco IOS XE Release 2.4If an RP becomes unreachable, this feature allows the RP to be detected and the mapping tables modified so that the unreachable RP is no longer used, and the new tables will be rapidly distributed throughout the domain.
The following sections provide information about this feature:
IPv6 multicast: IPv6 BSR bidirectional support
Cisco IOS XE Release 2.4
Bidirectional BSR support allows bidirectional RPs to be advertised in C-RP messages and bidirectional ranges in the BSM.
The following section provides information about this feature:
IPv6 multicast: MRIB
Cisco IOS XE Release 2.1
The MRIB is a protocol-independent repository of multicast routing entries instantiated by multicast routing protocols (routing clients).
The following sections provide information about this feature:
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The following commands were modified by this feature: clear ipv6 pim topology, debug ipv6 mrib client, debug ipv6 mrib io, debug ipv6 mrib proxy, debug ipv6 mrib route, debug ipv6 mrib table, show ipv6 mrib client, show ipv6 mrib route, show ipv6 pim topology
IPv6 multicast: SSM mapping for MLDv1 SSM
Cisco IOS XE Release 2.1
Cisco IOS XE Release 2.4
This feature allows deployment of IPv6 SSM with hosts that are incapable of providing MLD version 2 support in their TCP/IP host stack and their IP multicast receiving application.
The following sections provide information about this feature:
The following commands were modified by this feature: ipv6 mld ssm-map enable, ipv6 mld ssm-map query dns, ipv6 mld ssm-map static, show ipv6 mld ssm-map
IPv6 multicast: IPv6 BSR—ability to configure RP mapping
Cisco IOS XE Release 2.4
This feature allows IPv6 multicast routers to be statically configured to announce scope-to-RP mappings directly from the BSR instead of learning them from candidate-RP messages.
The following sections provide information about this feature:
IPv6 multicast: MLD group limits
Cisco IOS XE Release 2.1
The MLD group limits feature provides protection against denial of service (DoS) attacks caused by MLD packets.
The following sections provide information about this feature:
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The following commands were modified by this feature: ipv6 mld limit, ipv6 mld state-limit,
Distributed MFIB (dMFIB)
Cisco IOS XE Release 2.1
Distributed MFIB is used to switch multicast IPv6 packets on distributed platforms.
The following sections provide information about this feature:
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