Draft-rosen multicast VPN is a legacy feature.
We recommend that you implement multiprotocol BGP-based multicast
VPNs on multicast VPNs. Use this section to maintain your already
existing draft-rosen multicast VPNs. To implement draft-rosen IPv4
multicast for a Layer 3 VPN, configure the following:
Configuring BGP, MPLS, RSVP, and an IGP on the PE and Core
Routers
To send multicast traffic across a Layer 3 VPN,
you must configure network protocols to handle intradomain
routing (an interior gateway protocol [IGP], such as Open
Shortest Path First [OSPF] or Intermediate System-to-Intermediate
System [IS-IS]), interdomain routing (Border
Gateway Protocol [BGP]), label switching (Multiprotocol
Label Switching [MPLS]), and path signaling (Resource
Reservation Protocol [RSVP]). For more information about these protocols
and examples of how to configure these protocols to support a Layer
3 VPN, see the JUNOS VPNs Configuration Guide.
Note:
In multicast Layer 3 VPNs, the multicast PE routers
must use the primary loopback address (or router ID) for sessions
with their internal BGP peers. If the PE routers use a route reflector
with next-hop self-configured, Layer 3 multicast over VPN does not
work because PIM cannot transmit upstream interface information for
multicast sources behind remote PE routers into the network core.
Multicast Layer 3 VPNs require the BGP next-hop address
of the VPN route to match the BGP next-hop address of the loopback
VRF instance address.
Creating a Unique Logical Loopback Interface for the Routing
Instance
To facilitate the PIM protocol within a Layer 3
VPN, configure a unique loopback interface for the routing instance
at the [edit interfaces lo0 unit] hierarchy level:
[edit interfaces]
lo0 {
unit 1 {
family inet {
address ip-address;
}
}
}
Configuring the Master PIM Instance on the PE Router
To configure the master PIM instance that communicates
with other PIM neighbors and the SP-RP within the service provider
network, include the pim statement at the [edit protocols] hierarchy level. The example shown enables PIM sparse mode.
[edit protocols]
pim {
rp {
static {
address ip-address;
}
}
interface all {
mode sparse;
version 2;
}
}
Configuring PIM and the VPN Group Address in a Routing Instance
The configuration syntax for PIM in a Layer 3 instance
is available at the [edit routing-instances protocols pim] hierarchy level. It is similar to the global PIM configuration syntax
found at the [edit protocols pim] hierarchy level.
In JUNOS Release 5.3 and later, you can include
the vpn-group-address statement at the [edit routing-instances instance-name protocols pim] hierarchy level. You
include this statement within the routing instance and specify the
multicast group address for a particular VPN. Only one vpn-group-address statement can be configured per VPN, and this address should be
unique on a per-VPN basis. To review how the VPN group address is
used within GRE packet headers, see Stage 2 in Dual PIM Multicast VPNs: Draft Rosen.
Keep in mind that each PE router contains two entries
of PIM: one for the master instance of PIM that connects through the
service provider network and a second for the routing instance that
connects to the CE router. The RP listed within the routing instance
is the VPN C-RP, whereas the RP in the master PIM instance is an SP-RP.
The following sample configuration shows a PE router with PIM enabled
for sparse-dense mode in the VPN instance.
[edit]
routing-instances {
instance-name {
.....
protocols {
.....
pim {
vpn-group-address group-address;
rp {
static {
address ip-address;
}
}
interface interface-name {
mode sparse-dense;
version 2;
}
interface lo0.1 {
mode sparse-dense;
version 2;
}
}
}
}
}
Note:
In JUNOS Release 5.5 and later, you can configure
PIM dense mode with the dense statement at the [edit
routing-instances pim mode] hierarchy level. Sparse mode is available
at this same hierarchy level in JUNOS Release 5.3 and later.
Option: Configuring PIM Sparse Mode Graceful Restart for a
Layer 3 VPN
Graceful restart permits a routing platform to
continue forwarding multicast traffic to neighbors while the routing
protocol process restarts. To enable graceful restart for PIM sparse
mode in a Layer 3 VPN, include the graceful-restart statement
at both the [edit routing-options] and [edit routing-instances instance-name routing-options] hierarchy levels.
To disable graceful restart in a Layer 3 VPN, include the disable statement at the [edit routing-instances instance-name protocols pim graceful-restart] hierarchy level.
[edit]
routing-options {
graceful-restart {
disable;
restart-duration seconds;
}
}
routing-instances {
instance-name {
.....
protocols {
pim {
graceful-restart {
disable;
restart-duration seconds;
}
}
}
routing-options {
graceful-restart {
disable;
restart-duration seconds;
}
}
}
}
For more information about PIM sparse mode graceful
restart in a Layer 3 VPN, see the JUNOS High Availability Configuration Guide or the JUNOS Multicast Protocols Configuration Guide.
Option: Configuring Multicast Distribution Trees for Data
By using multicast distribution trees (MDTs) for
data in a Layer 3 VPN, you can prevent multicast packets from being
flooded unnecessarily to specified provider edge (PE) routers within
a VPN group. This option is primarily useful for PE routers in your
Layer 3 VPN multicast network that have no receivers for the multicast
traffic from a particular source.
When a PE router directly connected to the multicast
source receives Layer 3 VPN multicast traffic exceeding a configured
threshold, a new data-MDT tunnel is established between the source
PE router and its remote PE router neighbors. Neighbors that do not
have receivers for the multicast traffic ignore the new tunnel. Conversely,
neighbors that do have receivers for the multicast traffic link to
the data-MDT tunnel, which is created based on the multicast data
in the VPN. If the multicast traffic level drops back below the threshold,
the data-MDT tunnel is torn down automatically and traffic flows back
across the original Layer 3 VPN PIM tunnel.
To specify when the PE router directly connected
to the multicast source should create a new data-MDT tunnel, you must
configure the maximum threshold value by including the rate statement at the [edit routing-instances instance-name protocols pim mdt threshold group group-address source source-address] hierarchy level.
The data rate is specified in kilobits per second (Kbps). To specify
the maximum number of data-MDT tunnels that can be created for a single
routing instance, include the tunnel-limit statement at the [edit routing-instances instance-name protocols
pim mdt] hierarchy level. To specify the IP group range used
when a new data-MDT tunnel needs to be initiated on the PE router,
include the group-range statement at the [edit routing-instances instance-name protocols pim mdt] hierarchy level.
Note:
Because MDT applies to VPNs and VRF routing instances,
you cannot configure MDT statements in the master routing instance.
If you configure MDT in the master routing instance, the configuration
commit operation will fail.
For more information about MDT, see the JUNOS Multicast Protocols Configuration
Guide.
Option: Configuring MSDP Within a Layer 3 VPN
MSDP, defined in RFC 3618, allows a PIM-enabled
network to connect multicast routing domains. It typically runs on
the same router as a PIM sparse-mode rendezvous point (RP). Each MSDP
router establishes adjacencies with internal and external MSDP peers
similar to adjacency establishment for BGP peers. MSDP peer routers
inform each other about active sources within the domain. When the
peers detect active sources, they send explicit Join messages to the
active source.
You can configure MSDP in the master instance of
a routing platform, or in the following types of routing instances:
Forwarding
No forwarding
Virtual router
VPLS
VRF
To configure MSDP in a Layer 3 VPN, include the msdp statement at the [edit routing-instances instance-name protocols] hierarchy level and specify
local and peer addresses. You must also configure PIM sparse mode
in the routing instance and specify a rendezvous point.
[edit routing-instances instance-name protocols]
pim {
rp {
local {
address ip-address;
}
}
interface interface-name;
}
msdp {
local-address local-ip-address;
peer peer-ip-address;
}
To view information about the operation of MSDP
within a Layer 3 VPN instance, issue the show msdp instance, show msdp statistics instance, show msdp source instance, and show msdp source-active instance commands. For more
information about MSDP, see the JUNOS Multicast Protocols
Configuration Guide.
