mVPN网络中IOS-XR PE路由器核心树协议的迁移
简介
本文档介绍如何将组播VPN(mVPN)协议无关组播(PIM)基于核心树的组播分布树(MDT)迁移到多点标签分布协议(mLDP)基于核心树的MDT。此外，还详细说明了迁移时如何发送数据MDT信号。本文档仅介绍运行Cisco IOS®-XR的入口提供商边缘(PE)路由器的迁移。
核心树协议的迁移
Dual-encap是指能够同时将客户(C)组播流转发到不同类型核心树的入口路由器。例如，入口PE路由器将一个C组播流同时转发到基于PIM的核心树和基于mLDP的核心树上。这是将mVPN从一个核心树类型成功迁移到另一个核心树类型的要求。
PIM和mLDP支持双封装。
多协议标签交换(MPLS)P2MP流量工程(TE)不支持双封装。
默认MDT通用路由封装(GRE)和默认MDT mLDP迁移或共存依赖于入口PE路由器同时向基于PIM的核心树和基于mLDP的核心树转发一个C组播流这一事实。当入口PE转发到两个MDT时，出口PE路由器可以逐个从一个核心树类型迁移到另一个核心树类型。
通常，PE路由将从使用基于PIM的核心树的最旧mVPN部署模式迁移到使用基于mLDP的树的mVPN部署模式。最旧的mVPN实施是配置文件0，它是基于PIM的核心树、无边界网关协议(BGP)自动发现(AD)和重叠信令中的PIM。然而，迁移也可以以相反的方式发生。
让我们来看看此迁移方案，因为这是最常见的迁移：从核心中的GRE（配置文件0）到默认MDT mLDP配置文件。
可能有几种默认mLDP配置文件。
我们来看一下这些产品：
- 没有BGP AD的mLDP
- 具有BGP AD和PIM C信令的mLDP
- 带有BGP AD和BGP C信令的mLDP
在后一种情况下，C信令协议也发生了迁移。
需要记住的一件事是，使用BGP AD时，默认情况下数据MDT由BGP发出信号。如果没有BGP AD，则数据MDT无法通过BGP发出信号。
无论如何，入口PE必须同时配置配置文件0和mLDP配置文件。入口PE将C组播流量转发到两个核心树协议的两个MDT（默认或数据）上。因此，必须在入口PE上配置两个默认MDT。
如果出口PE能够运行核心树协议PIM和mLDP，它可以决定从哪个树提取C组播流量。这可以通过在出口PE上配置反向路径转发(RPF)策略来实现。
如果出口PE路由器仅支持配置文件0，则该PE将仅加入核心中的PIM树，并在基于PIM的树上接收C组播流。
C组播协议迁移
C组播协议可以从PIM迁移到BGP，反之亦然。这是通过将出口PE配置为选择PIM或BGP作为重叠协议来实现的。它是通过PIM或BGP发出加入的出口PE。入口PE可以在迁移场景中接收和处理两者。
下面是在出口PE上配置的C组播协议的迁移示例：
router pim
vrf one
address-family ipv4
rpf topology route-policy rpf-for-one
mdt c-multicast-routing bgp
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
route-policy rpf-for-one
set core-tree mldp-default
end-policy
!
BGP作为重叠信令协议启用。默认值为PIM。
场景
查看图1.以查看用于这些场景的设置。
图 1.
在这些情况下，您至少有一个传统PE路由器作为接收器PE路由器。这是只运行配置文件0（默认MDT - GRE - PIM组播信令）的路由器。
此路由器必须配置BGP IPv4 MDT。
至少有一个接收器 — PE路由器运行基于mLDP的配置文件。这些都是默认MDT mLDP配置文件(1、9、13、12、17)、所有分区的MDT mLDP配置文件(2、4、5、14、15)和配置文件7。也支持P2MP TE的配置文件8。
入口PE路由器是双封装路由器：它运行配置文件0和基于mLDP的配置文件。
此入口PE路由器始终必须在基于PIM的MDT和基于mLDP的MDT上转发流量。这些MDT可以是默认MDT和数据MDT。
作为传统路由器，请采用运行IOS的路由器，该路由器只能运行配置文件0。传统路由器的配置如下。
vrf definition one
rd 1:3
vpn id 1:1
route-target export 1:1
route-target import 1:1
!
address-family ipv4
mdt default 232.1.1.1
exit-address-family
需要配置BGP IPv4 MDT:
router bgp 1
…
address-family ipv4 mdt
neighbor 10.1.100.7 activate
neighbor 10.1.100.7 send-community extended
exit-address-family
!
…
场景 1.
有一个或多个传统PE路由器作为Receiver-PE路由器。
有一个或多个PE路由器作为运行配置文件1（默认MDT - mLDP MP2MP PIM组播信令）的接收器 — PE路由器。
根本没有BGP AD或BGP C组播信令。
运行配置文件1的Receiver-PE路由器的配置：
vrf one
vpn id 1:1
address-family ipv4 unicast
import route-target
1:1
!
export route-target
1:1
!
!
router pim
vrf one
address-family ipv4
rpf topology route-policy rpf-for-one
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
route-policy rpf-for-one
set core-tree mldp-default
end-policy
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
mdt default mldp ipv4 10.1.100.7
mdt data 100
rate-per-route
interface all enable
!
accounting per-prefix
!
!
!
mpls ldp
mldp
logging notifications
address-family ipv4
!
!
!
route-policy rpf-for-one
set core-tree mldp-default
入口PE路由器的配置：
vrf one
vpn id 1:1
address-family ipv4 unicast
import route-target
1:1
!
export route-target
1:1
!
!
router pim
vrf one
address-family ipv4
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
interface all enable
!
mdt default ipv4 232.1.1.1
mdt default mldp ipv4 10.1.100.7
mdt data 255
mdt data 232.1.2.0/24
!
!
!
mpls ldp
mldp
logging notifications
address-family ipv4
!
!
!
入口PE路由器必须具有BGP地址系列IPv4 MDT，与传统PE路由器相同。
入口PE必须转发到两种类型的MDT:
Ingress-PE#show mrib vrf one route 232.100.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(10.2.2.9,232.100.1.1) RPF nbr: 10.2.2.9 Flags: RPF MT
MT Slot: 0/1/CPU0
Up: 00:56:09
Incoming Interface List
GigabitEthernet0/1/0/0 Flags: A, Up: 00:56:09
Outgoing Interface List
mdtone Flags: F NS MI MT MA, Up: 00:22:59 <<< PIM-based tree
Lmdtone Flags: F NS LMI MT MA, Up: 00:56:09 <<< mLDP-based tree
入口PE应该将接口mdtone上的传统PE和接口Lmdtone上的配置文件1 PE视为PIM邻居：
Ingress-PE#show pim vrf one neighbor
PIM neighbors in VRF one
Flag: B - Bidir capable, P - Proxy capable, DR - Designated Router,
E - ECMP Redirect capable
* indicates the neighbor created for this router
Neighbor Address Interface Uptime Expires DR pri Flags
10.1.100.1 Lmdtone 6w1d 00:01:29 1 P
10.1.100.2* Lmdtone 6w1d 00:01:15 1 (DR) P
10.1.100.2* mdtone 5w0d 00:01:30 1 P
10.1.100.3 mdtone 00:50:20 00:01:30 1 (DR) P
入口PE上的“debug pim vrf one mdt data”：
您将看到发送了第1类（PIM核心树）和第2类（mLDP核心树）PIM加入TLV。第一个在mdtone上，第二个在Lmdtone上。
pim[1140]: [13] MDT Grp lookup: Return match for grp 232.1.2.4 src 10.1.100.2 in local list (-)
pim[1140]: [13] In mdt timers process...
pim[1140]: [13] Processing MDT JOIN SEND timer for MDT null core mldp pointer in one
pim[1140]: [13] In join_send_update_timer: route->mt_head 50c53b44
pim[1140]: [13] Create new MDT tlv buffer for one for type 0x1
pim[1140]: [13] Buffer allocated for one mtu 1348 size 0
pim[1140]: [13] TLV type set to 0x1
pim[1140]: [13] TLV added for one mtu 1348 size 16
pim[1140]: [13] MDT cache upd: pe 0.0.0.0, (10.2.2.9,232.100.1.1), mdt_type 0x1, core (10.1.100.2,232.1.2.4), for vrf one [local, -], mt_lc 0x11, mdt_if 'mdtone', cache NULL
pim[1140]: [13] Looked up cache pe 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x1 in one (found) - No error
pim[1140]: [13] Cache get: Found entry for 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x1 in one
pim[1140]: [13] pim_mvrf_mdt_cache_update:946, mt_lc 0x11, copied mt_mdt_ifname 'mdtone'
pim[1140]: [13] Create new MDT tlv buffer for one for type 0x2
pim[1140]: [13] Buffer allocated for one mtu 1348 size 0
pim[1140]: [13] TLV type set to 0x2, o_type 0x2
pim[1140]: [13] TLV added for one mtu 1348 size 36
pim[1140]: [13] MDT cache upd: pe 0.0.0.0, (10.2.2.9,232.100.1.1), mdt_type 0x2, core src 10.1.100.2, id [mdt 1:1 1], for vrf one [local, -], mt_lc 0x11, mdt_if 'Lmdtone', cache NULL
pim[1140]: [13] Looked up cache pe 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x2 in one (found) - No error
pim[1140]: [13] Cache get: Found entry for 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
pim[1140]: [13] pim_mvrf_mdt_cache_update:946, mt_lc 0x11, copied mt_mdt_ifname 'Lmdtone'
pim[1140]: [13] Set next send time for core type (0x0/0x2) (v: 10.2.2.9,232.100.1.1) in one
pim[1140]: [13] 2. Flush MDT Join for one on Lmdtone(10.1.100.2) 6 (Cnt:1, Reached size 36 MTU 1348)
pim[1140]: [13] 2. Flush MDT Join for one (Lo0) 10.1.100.2
pim[1140]: [13] 2. Flush MDT Join for one on mdtone(10.1.100.2) 6 (Cnt:1, Reached size 16 MTU 1348)
pim[1140]: [13] 2. Flush MDT Join for one (Lo0) 10.1.100.2
Ingress-PE#show pim vrf one mdt cache
Core Source Cust (Source, Group) Core Data Expires
10.1.100.2 (10.2.2.9, 232.100.1.1) 232.1.2.4 00:02:36
10.1.100.2 (10.2.2.9, 232.100.1.1) [mdt 1:1 1] 00:02:36
传统出口PE:
"debug ip pim vrf one 232.100.1.1":
PIM(1): Receive MDT Packet (55759) from 10.1.100.2 (Tunnel3), length (ip: 44, udp: 24), ttl: 1PIM(1): TLV type: 1 length: 16 MDT Packet length: 16
传统PE缓存PIM加入TLV:
Legacy-PE#show ip pim vrf one mdt receive
Joined MDT-data [group/mdt number : source] uptime/expires for VRF: one
[232.1.2.4 : 10.1.100.2] 00:01:10/00:02:45
传统PE在核心中加入Data MDT:
Legacy-PE#show ip mroute vrf one 232.100.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(10.2.2.9, 232.100.1.1), 00:08:48/00:02:34, flags: sTY
Incoming interface: Tunnel3, RPF nbr 10.1.100.2, MDT:[10.1.100.2,232.1.2.4]/00:02:46
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 00:08:48/00:02:34
配置文件1接收器 — PE也接收PIM加入TLV，但对于基于mLDP的数据MDT:
Egress-PE#debug pim vrf one mdt data
pim[1161]: [13] Received MDT Packet on Lmdtone (vrf:one) from 10.1.100.2, len 36
pim[1161]: [13] Processing type 2 tlv
pim[1161]: [13] Received MDT Join TLV from 10.1.100.2 for cust route 10.2.2.9,232.100.1.1
MDT number 1 len 36
pim[1161]: [13] Looked up cache pe 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
(found) - No error
pim[1161]: [13] MDT cache upd: pe 10.1.100.2, (10.2.2.9,232.100.1.1), mdt_type 0x2, core
src 10.1.100.2, id [mdt 1:1 1], for vrf one [remote, -], mt_lc 0xffffffff, mdt_if 'xxx',
cache NULL
pim[1161]: [13] Looked up cache pe 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
(found) - No error
pim[1161]: [13] Cache get: Found entry for 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2
in one
RP/0/RP1/CPU0:Nov 27 16:04:02.726 : Return match for [mdt 1:1 1] src 10.1.100.2 in remote
list (one)
pim[1161]: [13] Remote join: MDT [mdt 1:1 1] known in one. Refcount (1, 1)
Egress-PE#show pim vrf one mdt cache
Core Source Cust (Source, Group) Core Data Expires
10.1.100.2 (10.2.2.9, 232.100.1.1) [mdt 1:1 1] 00:02:12
Egress-PE#show mrib vrf one route 232.100.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(10.2.2.9,232.100.1.1) RPF nbr: 10.1.100.2 Flags: RPF
Up: 00:45:20
Incoming Interface List
Lmdtone Flags: A LMI, Up: 00:45:20
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS LI, Up: 00:45:20
场景 2：
有一个或多个传统PE路由器作为接收器 — PE路由器。
有一个或多个PE路由器作为运行配置文件9（默认MDT - mLDP MP2MP BGP-AD PIM组播信令）的接收器 — PE路由器。
涉及BGP AD，但不涉及BGP C组播信令。
运行Profile 9的Receiver-PE路由器的配置：
vrf one
vpn id 1:1
address-family ipv4 unicast
import route-target
1:1
!
export route-target
1:1
!
!
router pim
vrf one
address-family ipv4
rpf topology route-policy rpf-for-one
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
route-policy rpf-for-one
set core-tree mldp-default
end-policy
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
rate-per-route
interface all enable
accounting per-prefix
bgp auto-discovery mldp
!
mdt default mldp ipv4 10.1.100.7
!
!
!
router bgp 1
!
address-family vpnv4 unicast
!
!
address-family ipv4 mvpn
!
!
neighbor 10.1.100.7 <<< iBGP neighbor
remote-as 1
update-source Loopback0
address-family vpnv4 unicast
!
address-family ipv4 mvpn
!
!
vrf one
rd 1:1
address-family ipv4 unicast
redistribute connected
!
address-family ipv4 mvpn
!
!
mpls ldp
mldp
logging notifications
address-family ipv4
!
!
!
入口PE路由器必须具有BGP地址系列IPv4 MDT，与传统PE路由器相同。入口PE路由器必须具有BGP地址系列IPv4 MVPN，与Profile 9出口PE路由器的功能匹配。
入口PE路由器的配置：
vrf one
vpn id 1:1
address-family ipv4 unicast
import route-target
1:1
!
export route-target
1:1
!
!
address-family ipv6 unicast
!
!
router pim
vrf one
address-family ipv4
mdt c-multicast-routing pim
announce-pim-join-tlv
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
interface all enable
bgp auto-discovery mldp
!
mdt default ipv4 232.1.1.1
mdt default mldp ipv4 10.1.100.7
mdt data 255
mdt data 232.1.2.0/24
!
!
!
router bgp 1
address-family vpnv4 unicast
!
address-family ipv4 mdt
!
address-family ipv4 mvpn
!
neighbor 10.1.100.7 <<< iBGP neighbor
remote-as 1
update-source Loopback0
address-family vpnv4 unicast
!
address-family ipv4 mdt
!
address-family ipv4 mvpn
!
!
vrf one
rd 1:2
address-family ipv4 unicast
redistribute connected
!
address-family ipv4 mvpn
!
mpls ldp
mldp
logging notifications
address-family ipv4
!
!
!
如果没有命令“announce-pim-join-tlv”，如果启用BGP自动发现(AD)，入口PE路由器不会通过默认MDT发送PIM加入TLV消息。如果没有此命令，入口PE路由器仅发送BGP IPv4 mvpn route-type 3更新。配置文件9出口PE路由器会接收BGP更新并将数据MDT消息安装到其缓存中。传统PE路由器不运行BGP AD，因此不会通过BGP获取数据MDT加入消息。
入口PE必须将C组播流量转发到两种类型的MDT:
Ingress-PE#show mrib vrf one route 232.100.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(10.2.2.9,232.100.1.1) RPF nbr: 10.2.2.9 Flags: RPF MT
MT Slot: 0/1/CPU0
Up: 05:03:56
Incoming Interface List
GigabitEthernet0/1/0/0 Flags: A, Up: 05:03:56
Outgoing Interface List
mdtone Flags: F NS MI MT MA, Up: 05:03:56
Lmdtone Flags: F NS LMI MT MA, Up: 05:03:12
入口PE应该将接口mdtone上的传统PE和接口Lmdtone上的配置文件9 PE视为PIM邻居：
Ingress-PE#show pim vrf one neighbor
PIM neighbors in VRF one
Flag: B - Bidir capable, P - Proxy capable, DR - Designated Router,
E - ECMP Redirect capable
* indicates the neighbor created for this router
Neighbor Address Interface Uptime Expires DR pri Flags
10.1.100.1 Lmdtone 6w1d 00:01:18 1 P
10.1.100.2* Lmdtone 6w1d 00:01:34 1 (DR) P
10.1.100.2* mdtone 5w0d 00:01:18 1 P
10.1.100.3 mdtone 06:00:03 00:01:21 1 (DR)
配置文件9出口PE接收数据MDT消息作为地址系列IPv4 MVPN中路由类型3的BGP更新：
Egress-PE#show bgp ipv4 mvpn vrf one
BGP router identifier 10.1.100.1, local AS number 1
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0x0 RD version: 1367879340
BGP main routing table version 92
BGP scan interval 60 secs
Status codes: s suppressed, d damped, h history, * valid, > best
i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 1:1 (default for vrf one)
*> [1][10.1.100.1]/40 0.0.0.0 0 i
*>i[1][10.1.100.2]/40 10.1.100.2 100 0 i
*>i[3][32][10.2.2.9][32][232.100.1.1][10.1.100.2]/120
10.1.100.2 100 0 i
Processed 3 prefixes, 3 paths
Egress-PE#show bgp ipv4 mvpn vrf one [3][32][10.2.2.9][32][232.100.1.1][10.1.100.2]/120
BGP routing table entry for [3][32][10.2.2.9][32][232.100.1.1][10.1.100.2]/120, Route
Distinguisher: 1:1
Versions:
Process bRIB/RIB SendTblVer
Speaker 92 92
Last Modified: Nov 27 20:25:32.474 for 00:44:22
Paths: (1 available, best #1, not advertised to EBGP peer)
Not advertised to any peer
Path #1: Received by speaker 0
Not advertised to any peer
Local
10.1.100.2 (metric 12) from 10.1.100.7 (10.1.100.2)
Origin IGP, localpref 100, valid, internal, best, group-best, import-candidate,
imported
Received Path ID 0, Local Path ID 1, version 92
Community: no-export
Extended community: RT:1:1
Originator: 10.1.100.2, Cluster list: 10.1.100.7
PMSI: flags 0x00, type 2, label 0, ID
0x060001040a016402000e02000b0000010000000100000001
Source VRF: default, Source Route Distinguisher: 1:2
此BGP路由是协议隧道类型2的路由类型3，即mLDP P2MP LSP（在P2MP mLSP LSP上构建的数据MDT）。由于未为PIM启用BGP AD，因此任何PIM树都没有BGP路由类型3条目。
入口PE上的“debug pim vrf one mdt data”：
pim[1140]: [13] In mdt timers process...
pim[1140]: [13] Processing MDT JOIN SEND timer for MDT null core mldp pointer in one
pim[1140]: [13] In join_send_update_timer: route->mt_head 50c53b44
pim[1140]: [13] Create new MDT tlv buffer for one for type 0x1
pim[1140]: [13] Buffer allocated for one mtu 1348 size 0
pim[1140]: [13] TLV type set to 0x1
pim[1140]: [13] TLV added for one mtu 1348 size 16
pim[1140]: [13] MDT cache upd: pe 0.0.0.0, (10.2.2.9,232.100.1.1), mdt_type 0x1, core
(10.1.100.2,232.1.2.5), for vrf one [local, -], mt_lc 0x11, mdt_if 'mdtone', cache NULL
pim[1140]: [13] Looked up cache pe 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x1 in one
(found) - No error
pim[1140]: [13] Cache get: Found entry for 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x1 in
one
pim[1140]: [13] pim_mvrf_mdt_cache_update:946, mt_lc 0x11, copied mt_mdt_ifname 'mdtone'
pim[1140]: [13] Create new MDT tlv buffer for one for type 0x2
pim[1140]: [13] Buffer allocated for one mtu 1348 size 0
pim[1140]: [13] TLV type set to 0x2, o_type 0x2
pim[1140]: [13] TLV added for one mtu 1348 size 36
pim[1140]: [13] MDT cache upd: pe 0.0.0.0, (10.2.2.9,232.100.1.1), mdt_type 0x2, core src
10.1.100.2, id [mdt 1:1 1], for vrf one [local, -], mt_lc 0x11, mdt_if 'Lmdtone', cache
NULL
: pim[1140]: [13] Looked up cache pe 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
(found) - No error
pim[1140]: [13] Cache get: Found entry for 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x2 in
one
pim[1140]: [13] pim_mvrf_mdt_cache_update:946, mt_lc 0x11, copied mt_mdt_ifname 'Lmdtone'
pim[1140]: [13] Set next send time for core type (0x0/0x2) (v: 10.2.2.9,232.100.1.1) in
one
pim[1140]: [13] 2. Flush MDT Join for one on Lmdtone(10.1.100.2) 6 (Cnt:1, Reached size
36 MTU 1348)
pim[1140]: [13] 2. Flush MDT Join for one (Lo0) 10.1.100.2
pim[1140]: [13] 2. Flush MDT Join for one on mdtone(10.1.100.2) 6 (Cnt:1, Reached size 16
MTU 1348)
pim[1140]: [13] 2. Flush MDT Join for one (Lo0) 10.1.100.2
入口PE为基于PIM和基于mLDP的数据MDT发送PIM加入TLV。
在传统PE上：
"debug ip pim vrf one 232.100.1.1":
PIM(1): Receive MDT Packet (56333) from 10.1.100.2 (Tunnel3), length (ip: 44, udp: 24), ttl: 1
PIM(1): TLV type: 1 length: 16 MDT Packet length: 16
传统PE接收并缓存PIM加入TLV:
Legacy-PE#show ip pim vrf one mdt receive
Joined MDT-data [group/mdt number : source] uptime/expires for VRF: one
[232.1.2.5 : 10.1.100.2] 00:23:30/00:02:33
传统PE在核心中加入Data MDT:
Legacy-PE#show ip mroute vrf one 232.100.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(10.2.2.9, 232.100.1.1), 05:13:35/00:03:02, flags: sTY
Incoming interface: Tunnel3, RPF nbr 10.1.100.2, MDT:[10.1.100.2,232.1.2.5]/00:02:37
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 05:13:35/00:03:02
Profile 9 Receiver-PE。
配置文件9出口PE上的“debug pim vrf one mdt data”：
pim[1161]: [13] Received MDT Packet on Lmdtone (vrf:one) from 10.1.100.2, len 36
pim[1161]: [13] Processing type 2 tlv
pim[1161]: [13] Received MDT Join TLV from 10.1.100.2 for cust route 10.2.2.9,232.100.1.1
MDT number 1 len 36
pim[1161]: [13] Looked up cache pe 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
(found) - No error
pim[1161]: [13] MDT cache upd: pe 10.1.100.2, (10.2.2.9,232.100.1.1), mdt_type 0x2, core
src 10.1.100.2, id [mdt 1:1 1], for vrf one [remote, -], mt_lc 0xffffffff, mdt_if 'xxx',
cache NULL
pim[1161]: [13] Looked up cache pe 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
(found) - No error
pim[1161]: [13] Cache get: Found entry for 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2
in one
pim[1161]: [13] MDT lookup: Return match for [mdt 1:1 1] src 10.1.100.2 in remote list
(one)
pim[1161]: [13] Remote join: MDT [mdt 1:1 1] known in one. Refcount (1, 1)
配置文件9接收器 — PE接收并缓存PIM加入TLV。由于从入口PE接收路由类型3的BGP更新消息，配置文件9接收器PE也获知了数据MDT。PIM加入TLV和BGP更新消息route-type是等效的，并且包含有关数据MDT的核心树隧道的相同信息。
Egress-PE#show pim vrf one mdt cache
Core Source Cust (Source, Group) Core Data Expires
10.1.100.2 (10.2.2.9, 232.100.1.1) [mdt 1:1 1] 00:02:35
Egress-PE#show mrib vrf one route 232.100.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(10.2.2.9,232.100.1.1) RPF nbr: 10.1.100.2 Flags: RPF
Up: 05:10:22
Incoming Interface List
Lmdtone Flags: A LMI, Up: 05:10:22
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS LI, Up: 05:10:22
场景 3：
有一个或多个传统PE路由器作为Receiver-PE路由器。
有一个或多个PE路由器作为运行配置文件13的接收器 — PE路由器（默认MDT - mLDP MP2MP BGP-AD BGP C-mcast信令）。
存在涉及BGP AD和BGP C组播信令。
运行配置文件13的Receiver-PE路由器的配置：
vrf one
vpn id 1:1
address-family ipv4 unicast
import route-target
1:1
!
export route-target
1:1
!
!
router pim
vrf one
address-family ipv4
rpf topology route-policy rpf-for-one
mdt c-multicast-routing bgp
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
route-policy rpf-for-one
set core-tree mldp-default
end-policy
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
rate-per-route
interface all enable
accounting per-prefix
bgp auto-discovery mldp
!
mdt default mldp ipv4 10.1.100.7
!
!
!
router bgp 1
!
address-family vpnv4 unicast
!
!
address-family ipv4 mvpn
!
!
neighbor 10.1.100.7 <<< iBGP neighbor
remote-as 1
update-source Loopback0
!
address-family vpnv4 unicast
!
address-family ipv4 mvpn
!
!
vrf one
rd 1:1
address-family ipv4 unicast
redistribute connected
!
address-family ipv4 mvpn
!
!
mpls ldp
mldp
logging notifications
address-family ipv4
!
!
!
入口PE路由器的配置：
vrf one
vpn id 1:1
address-family ipv4 unicast
import route-target
1:1
!
export route-target
1:1
!
!
address-family ipv6 unicast
!
!
router pim
vrf one
address-family ipv4
mdt c-multicast-routing bgp
announce-pim-join-tlv
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
interface all enable
mdt default ipv4 232.1.1.1
mdt default mldp ipv4 10.1.100.7
mdt data 255
mdt data 232.1.2.0/24
!
!
!
router bgp 1
address-family vpnv4 unicast
!
address-family ipv4 mdt
!
address-family ipv4 mvpn
!
neighbor 10.1.100.7 <<< iBGP neighbor
remote-as 1
update-source Loopback0
address-family vpnv4 unicast
!
address-family ipv4 mdt
!
address-family ipv4 mvpn
!
!
vrf one
rd 1:2
address-family ipv4 unicast
redistribute connected
!
address-family ipv4 mvpn
!
mpls ldp
mldp
logging notifications
address-family ipv4
!
!
!
如果没有命令announce-pim-join-tlv，如果启用BGP AD，入口PE路由器不会通过默认MDT发送PIM加入TLV消息。如果没有此命令，入口PE路由器仅发送BGP IPv4 mvpn route-type 3更新。配置文件13出口PE路由器会接收BGP更新并将数据MDT消息安装到其缓存中。传统PE路由器不运行BGP AD，因此不会通过BGP获取数据MDT加入消息。
入口PE必须转发到两种类型的MDT:
Ingress-PE#show mrib vrf one route 232.100.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(10.2.2.9,232.100.1.1) RPF nbr: 10.2.2.9 Flags: RPF MT
MT Slot: 0/1/CPU0
Up: 19:49:27
Incoming Interface List
GigabitEthernet0/1/0/0 Flags: A, Up: 19:49:27
Outgoing Interface List
mdtone Flags: F MI MT MA, Up: 19:49:27
Lmdtone Flags: F LMI MT MA, Up: 01:10:15
入口PE应将接口模块上的传统PE视为PIM邻居。但是，接口Lmdtone上的配置文件13 PE不是PIM邻居的必备条件，因为BGP现在用作C组播信令协议。
入口PE上的“debug pim vrf one mdt data”：
pim[1140]: [13] In mdt timers process...
pim[1140]: [13] Processing MDT JOIN SEND timer for MDT null core mldp pointer in one
pim[1140]: [13] In join_send_update_timer: route->mt_head 50c53b44
pim[1140]: [13] Create new MDT tlv buffer for one for type 0x1
pim[1140]: [13] Buffer allocated for one mtu 1348 size 0
pim[1140]: [13] TLV type set to 0x1
pim[1140]: [13] TLV added for one mtu 1348 size 16
pim[1140]: [13] MDT cache upd: pe 0.0.0.0, (10.2.2.9,232.100.1.1), mdt_type 0x1, core (10.1.100.2,232.1.2.5), for vrf one [local, -], mt_lc 0x11, mdt_if 'mdtone', cache NULL
pim[1140]: [13] Looked up cache pe 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x1 in one (found) - No error
pim[1140]: [13] Cache get: Found entry for 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x1 in one
pim[1140]: [13] pim_mvrf_mdt_cache_update:946, mt_lc 0x11, copied mt_mdt_ifname 'mdtone'
pim[1140]: [13] Create new MDT tlv buffer for one for type 0x2
pim[1140]: [13] Buffer allocated for one mtu 1348 size 0
pim[1140]: [13] TLV type set to 0x2, o_type 0x2
pim[1140]: [13] TLV added for one mtu 1348 size 36
pim[1140]: [13] MDT cache upd: pe 0.0.0.0, (10.2.2.9,232.100.1.1), mdt_type 0x2, core src 10.1.100.2, id [mdt 1:1 1], for vrf one [local, -], mt_lc 0x11, mdt_if 'Lmdtone', cache NULL
pim[1140]: [13] Looked up cache pe 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x2 in one (found) - No error
pim[1140]: [13] Cache get: Found entry for 0.0.0.0(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
pim[1140]: [13] pim_mvrf_mdt_cache_update:946, mt_lc 0x11, copied mt_mdt_ifname 'Lmdtone'
pim[1140]: [13] Set next send time for core type (0x0/0x2) (v: 10.2.2.9,232.100.1.1) in one
pim[1140]: [13] 2. Flush MDT Join for one on Lmdtone(10.1.100.2) 6 (Cnt:1, Reached size 36 MTU 1348)
pim[1140]: [13] 2. Flush MDT Join for one (Lo0) 10.1.100.2
pim[1140]: [13] 2. Flush MDT Join for one on mdtone(10.1.100.2) 6 (Cnt:1, Reached size 16 MTU 1348)
pim[1140]: [13] 2. Flush MDT Join for one (Lo0) 10.1.100.2
pim[1140]: [13] MDT Grp lookup: Return match for grp 232.1.2.5 src 10.1.100.2 in local list (-)
入口PE为基于PIM和基于mLDP的数据MDT发送PIM加入TLV。
传统PE上的“debug ip pim vrf one 232.100.1.1”：
PIM(1): Receive MDT Packet (57957) from 10.1.100.2 (Tunnel3), length (ip: 44, udp: 24), ttl: 1
PIM(1): TLV type: 1 length: 16 MDT Packet length: 16
传统PE缓存PIM加入TLV:
Legacy-PE#show ip pim vrf one mdt receive
Joined MDT-data [group/mdt number : source] uptime/expires for VRF: one
[232.1.2.5 : 10.1.100.2] 00:03:36/00:02:24
传统PE在核心中加入Data MDT:
Legacy-PE#show ip mroute vrf one 232.100.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(10.2.2.9, 232.100.1.1), 18:53:53/00:02:50, flags: sTY
Incoming interface: Tunnel3, RPF nbr 10.1.100.2, MDT:[10.1.100.2,232.1.2.5]/00:02:02
Outgoing interface list:
GigabitEthernet1/1, Forward/Sparse, 18:53:53/00:02:50
配置文件13 Receiver-PE:
配置文件13出口PE上的“debug pim vrf one mdt data”：
pim[1161]: [13] Received MDT Packet on Lmdtone (vrf:one) from 10.1.100.2, len 36
pim[1161]: [13] Processing type 2 tlv
pim[1161]: [13] Received MDT Join TLV from 10.1.100.2 for cust route 10.2.2.9,232.100.1.1 MDT number 1 len 36
pim[1161]: [13] Looked up cache pe 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one (found) - No error
pim[1161]: [13] MDT cache upd: pe 10.1.100.2, (10.2.2.9,232.100.1.1), mdt_type 0x2, core src 10.1.100.2, id [mdt 1:1 1], for vrf one [remote, -], mt_lc 0xffffffff, mdt_if 'xxx', cache NULL
pim[1161]: [13] Looked up cache pe 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one (found) - No error
pim[1161]: [13] Cache get: Found entry for 10.1.100.2(10.2.2.9,232.100.1.1) mdt_type 0x2 in one
pim[1161]: [13] MDT lookup: Return match for [mdt 1:1 1] src 10.1.100.2 in remote list (one)
pim[1161]: [13] Remote join: MDT [mdt 1:1 1] known in one. Refcount (1, 1)
RP/0/RP1/CPU0:Legacy-PE#show pim vrf one mdt cache
Core Source Cust (Source, Group) Core Data Expires
10.1.100.2 (10.2.2.9, 232.100.1.1) [mdt 1:1 1] 00:02:21
配置文件13接收器 — PE接收并缓存基于mLDP的MDT的PIM加入TLV。由于从入口PE接收路由类型3的BGP更新消息，配置文件13接收器PE也获知了数据MDT。PIM加入TLV和BGP更新消息route-type是等效的，并且包含有关数据MDT的核心树隧道的相同信息。
Ingress-PE#show bgp ipv4 mvpn vrf one
BGP router identifier 10.1.100.1, local AS number 1
BGP generic scan interval 60 secs
BGP table state: Active
Table ID: 0x0 RD version: 1367879340
BGP main routing table version 93
BGP scan interval 60 secs
Status codes: s suppressed, d damped, h history, * valid, > best
i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
Route Distinguisher: 1:1 (default for vrf one)
*> [1][10.1.100.1]/40 0.0.0.0 0 i
*>i[1][10.1.100.2]/40 10.1.100.2 100 0 i
*>i[3][32][10.2.2.9][32][232.100.1.1][10.1.100.2]/120
10.1.100.2 100 0 i
*> [7][1:2][1][32][10.2.2.9][32][232.100.1.1]/184
0.0.0.0 0 i
Processed 4 prefixes, 4 paths
Egress-PE#show bgp ipv4 mvpn vrf one [3][32][10.2.2.9][32][232.100.1.1][10.1.100.2]/120
BGP routing table entry for [3][32][10.2.2.9][32][232.100.1.1][10.1.100.2]/120, Route Distinguisher: 1:1
Versions:
Process bRIB/RIB SendTblVer
Speaker 92 92
Paths: (1 available, best #1, not advertised to EBGP peer)
Not advertised to any peer
Path #1: Received by speaker 0
Not advertised to any peer
Local
10.1.100.2 (metric 12) from 10.1.100.7 (10.1.100.2)
Origin IGP, localpref 100, valid, internal, best, group-best, import-candidate, imported
Received Path ID 0, Local Path ID 1, version 92
Community: no-export
Extended community: RT:1:1
Originator: 10.1.100.2, Cluster list: 10.1.100.7
PMSI: flags 0x00, type 2, label 0, ID 0x060001040a016402000e02000b0000010000000100000001
Source VRF: default, Source Route Distinguisher: 1:2
此BGP路由是协议隧道类型2的路由类型3，即mLDP P2MP LSP（在P2MP mLSP LSP上构建的数据MDT）。任何PIM树都没有BGP路由类型3，因为未为PIM启用BGP AD。
还有一个路由类型7，因为配置文件13出口PE和入口PE之间启用了C组播信令。路由类型7 BGP更新从配置文件13出口PE发送到入口PE。
场景 4.
在此场景中，VPN情景中存在PIM稀疏模式。
有一个或多个传统PE路由器作为源PE路由器。
有一个或多个PE路由器作为运行配置文件13的接收器 — PE路由器（默认MDT - mLDP MP2MP BGP-AD BGP C-mcast信令）。存在涉及BGP AD和BGP C组播信令。由于这些PE路由器需要能够直接从源PE（传统PE路由器）接收流量，因此它们还需要运行配置文件0。
RP-PE是运行配置文件13（默认MDT - mLDP MP2MP BGP-AD BGP C-mcast信令）的PE路由器。存在涉及BGP AD和BGP C组播信令。由于RP-PE路由器需要能够直接从源PE（传统PE路由器）接收流量，因此它们还需要运行配置文件0。
组播路由在场景3中有效，但可能仅适用于源特定组播(SSM)。如果C信令为稀疏模式，则组播可能会失败。这取决于伦德斯视频点(RP)的位置。如果重叠中的信令只有(S， G)，则组播路由将如场景3中一样工作。如果RP位于接收方站点，则会发生这种情况。如果RP位于接收方的站点，则接收方PE不会通过PIM或BGP在重叠中发送(*, G)加入。但是，如果RP位于源PE或其他PE，则重叠中会有(*, G)和(S， G)信令。如果按照场景3中的配置完成此操作，则组播路由可能会失败。
请看图2。它显示了一个具有源PE（传统PE）、RP-PE(PE2)和接收器PE(PE1)的网络。
图 2.
出口PE路由器需要发出(*,G)的联合。它们将使用的协议取决于配置。出口PE将使用BGP，传统源PE路由器也将使用PIM（如果它也有接收器）。因此共享树将发出良好的信号。当源开始发送时将出现问题：不会发出源树信号。
问题
一旦源开始发送，RP将接收来自PIM第一跳路由器(FHR)的注册数据包。此处可能是Legacy-Source-PE路由器。然后，RP-PE需要向Legacy-Source-PE发送PIM(S，G)加入，因为Legacy-Source-PE不会将BGP作为重叠信令协议运行。但是，RP-PE将BGP配置为重叠信令协议。因此，旧版源PE永远不会收到来自RP-PE的PIM(S， G)加入消息，因此从源到RP的源树无法发信号。安装程序处于注册阶段。Legacy-Source-PE上的传出接口列表(OIL)为空：
Legacy-PE#show ip mroute vrf one 225.1.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 225.1.1.1), 00:05:47/stopped, RP 10.2.100.9, flags: SPF
Incoming interface: Tunnel3, RPF nbr 10.1.100.2
Outgoing interface list: Null
(10.2.3.10, 225.1.1.1), 00:05:47/00:02:42, flags: PFT
Incoming interface: GigabitEthernet1/1, RPF nbr 10.2.3.10
Outgoing interface list: Null
要解决此问题，您需要让RP-PE将(S， G)的PIM加入发送到旧版源PE，而RP-PE仍启用了BGP作为非旧版路由器的重叠信令协议。如果源在非传统路由器的后面联机，则RP-PE需要向该非传统路由器发送路由类型7 BGP更新消息。
RP-PE可以同时使用PIM和BGP作为重叠信令。路由策略将决定选择哪一个。您需要在VRF的路由器PIM下使用migration命令。对于图2所示的网络，这是RP-PE上所需的配置：
router pim
vrf one
address-family ipv4
rpf topology route-policy rpf-for-one
mdt c-multicast-routing bgp
migration route-policy PIM-to-BGP
announce-pim-join-tlv
!
interface GigabitEthernet0/1/0/0
enable
!
!
!
!
route-policy rpf-for-one
if next-hop in (10.1.100.3/32) then
set core-tree pim-default
else
set core-tree mldp-default
endif
end-policy
!
route-policy PIM-to-BGP
if next-hop in (10.1.100.3/32) then
set c-multicast-routing pim
else
set c-multicast-routing bgp
endif
end-policy
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
rate-per-route
interface all enable
accounting per-prefix
bgp auto-discovery mldp
!
mdt default ipv4 232.1.1.1
mdt default mldp ipv4 10.1.100.7
!
!
!
路由策略PIM到BGP指定如果远程PE路由器是10.1.100.3(Legacy-Source-PE)，则使用PIM作为重叠信令协议。否则（对于非传统PE路由器），BGP用作重叠信令协议。因此，RP-PE现在在基于PIM的默认MDT上向旧源PE发送PIM(S， G)加入。Legacy-Source-PE现在具有(S， G)条目：
Legacy-PE#show ip mroute vrf one 225.1.1.1
IP Multicast Routing Table
Flags: D - Dense, S - Sparse, B - Bidir Group, s - SSM Group, C - Connected,
L - Local, P - Pruned, R - RP-bit set, F - Register flag,
T - SPT-bit set, J - Join SPT, M - MSDP created entry, E - Extranet,
X - Proxy Join Timer Running, A - Candidate for MSDP Advertisement,
U - URD, I - Received Source Specific Host Report,
Z - Multicast Tunnel, z - MDT-data group sender,
Y - Joined MDT-data group, y - Sending to MDT-data group,
G - Received BGP C-Mroute, g - Sent BGP C-Mroute,
N - Received BGP Shared-Tree Prune, n - BGP C-Mroute suppressed,
Q - Received BGP S-A Route, q - Sent BGP S-A Route,
V - RD & Vector, v - Vector, p - PIM Joins on route,
x - VxLAN group
Outgoing interface flags: H - Hardware switched, A - Assert winner, p - PIM Join
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 225.1.1.1), 00:11:56/stopped, RP 10.2.100.9, flags: SPF
Incoming interface: Tunnel3, RPF nbr 10.1.100.2
Outgoing interface list: Null
(10.2.3.10, 225.1.1.1), 00:11:56/00:03:22, flags: FT
Incoming interface: GigabitEthernet1/1, RPF nbr 10.2.3.10
Outgoing interface list:
Tunnel3, Forward/Sparse, 00:00:11/00:03:18
如果RP-PE U-turn数据包，接收方可以接收组播数据包：它将从MDT接收的组播数据包转发到Lmdt树上。
RP/0/3/CPU1:PE2#show mrib vrf one route 225.1.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(*,225.1.1.1) RPF nbr: 10.2.2.9 Flags: C RPF
Up: 00:53:59
Incoming Interface List
GigabitEthernet0/1/0/0 Flags: A, Up: 00:53:59
Outgoing Interface List
Lmdtone Flags: F LMI, Up: 00:53:59
(10.2.3.10,225.1.1.1) RPF nbr: 10.1.100.3 Flags: RPF
Up: 00:03:00
Incoming Interface List
mdtone Flags: A MI, Up: 00:03:00
Outgoing Interface List
Lmdtone Flags: F NS LMI, Up: 00:03:00
无论最后一跳路由器(LHR)是否配置了SPT切换，组播流量都会继续通过共享树转发到RP-PE。查看图3.以查看组播流量的转发方式。
图 3.
出口PE没有(S， G)条目：
RP/0/RP1/CPU0:PE1#show mrib vrf one route 225.1.1.1
IP Multicast Routing Information Bas
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept, IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(*,225.1.1.1) RPF nbr: 10.1.100.2 Flags: C RPF
Up: 04:35:36
Incoming Interface List
Lmdtone Flags: A LMI, Up: 03:00:24
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS, Up: 04:35:36
如果Egress-PE是LHR，则它没有(S， G)条目。出口PE无法切换到(S， G)条目的原因是它没有收到来自PE路由器的BGP源活动路由。组播流量会如图3所示进行转发。
但是，Egress-PE可能不是LHR，但Egress-PE站点的CE路由器是LHR。如果CE路由器切换到源树，则出口PE将收到PIM(S， G)加入并安装(S， G)条目。
RP/0/RP1/CPU0:PE1#show mrib vrf one route 225.1.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(*,225.1.1.1) RPF nbr: 10.1.100.2 Flags: C RPF
Up: 00:04:51
Incoming Interface List
Lmdtone Flags: A LMI, Up: 00:04:51
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS, Up: 00:04:51
(10.2.3.10,225.1.1.1) RPF nbr: 10.1.100.3 Flags: RPF
Up: 00:00:27
Incoming Interface List
Lmdtone Flags: A LMI, Up: 00:00:27
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS, Up: 00:00:27
但是，Egress-PE现在将RPF连接到源，并查找路由器旧版源PE作为RPF邻居：
RP/0/RP1/CPU0:PE1#show pim vrf one rpf 10.2.3.10
Table: IPv4-Unicast-default
* 10.2.3.10/32 [200/0]
via Lmdtone with rpf neighbor 10.1.100.3
Connector: 1:3:10.1.100.3, Nexthop: 10.1.100.3
由于出口PE和传统Source PE之间没有MDT，因此，出口PE无法向传统Source PE发送加入。请记住，出口PE仅构建mLDP树并执行BGP客户信令。请记住，Legacy-Source-PE仅构建基于PIM的树，并且仅构建PIM客户信令。
但是，由于出口PE具有指向传入接口Lmdt的RPF信息，并且组播流量仍然从RP-PE到达该MDT，因此组播流量将转发到接收方，不会导致RPF失败。原因是RPF不执行严格RPF检查以检查组播流量是否实际从RPF邻居10.1.100.3（传统PE路由器）到达。请注意，Lmdt上的PE1上没有10.1.100.3的PIM邻接关系，因为传统PE不能有Lmdt，因为它仅将PIM作为核心树协议（配置文件0）运行：
RP/0/RP1/CPU0:PE1#show pim vrf one neighbor
PIM neighbors in VRF one
Flag: B - Bidir capable, P - Proxy capable, DR - Designated Router,
E - ECMP Redirect capable
* indicates the neighbor created for this router
Neighbor Address Interface Uptime Expires DR pri Flags
10.1.100.1* Lmdtone 01:32:46 00:01:32 100 (DR) P
10.1.100.2 Lmdtone 01:30:46 00:01:16 1 P
10.1.100.4 Lmdtone 01:30:38 00:01:24 1 P
10.1.100.1* mdtone 01:32:46 00:01:34 100 (DR) P
10.1.100.2 mdtone 01:32:45 00:01:29 1 P
10.1.100.3 mdtone 01:32:17 00:01:29 1 P
10.1.100.4 mdtone 01:32:43 00:01:20 1 P
10.2.1.1* GigabitEthernet0/0/0/9 01:32:46 00:01:18 100 B P E
10.2.1.8 GigabitEthernet0/0/0/9 01:32:39 00:01:16 100 (DR)
PE1选择Lmdt作为传入接口的原因是，这是从PE1上的RPF topology命令接收的信息：
route-policy rpf-for-one
set core-tree mldp-default
end-policy
!
如果PE1上的RPF仍然正常，则组播流量可以到达PE1后面的接收器。但是，流量不采用到核心中PE1的最短路径Legacy-PE。
解决方案
要解决此问题，必须将出口PE(PE1)配置为将基于PIM的MDT和BGP也配置为重叠信令。这种情况下，出口PE上需要此配置：
router pim
vrf one
address-family ipv4
rpf topology route-policy rpf-for-one
mdt c-multicast-routing bgp
migration route-policy PIM-to-BGP
announce-pim-join-tlv
!
rp-address 10.2.100.9 override
!
interface GigabitEthernet0/0/0/9
enable
!
!
!
!
route-policy rpf-for-one
if next-hop in (10.1.100.3/32) then
set core-tree pim-default
else
set core-tree mldp-default
endif
end-policy
!
route-policy PIM-to-BGP
if next-hop in (10.1.100.3/32) then
set c-multicast-routing pim
else
set c-multicast-routing bgp
endif
end-policy
!
multicast-routing
vrf one
address-family ipv4
mdt source Loopback0
rate-per-route
interface all enable
accounting per-prefix
bgp auto-discovery mldp
!
mdt default ipv4 232.1.1.1
mdt default mldp ipv4 10.1.100.7
!
!
!
请看图4。现在，传统PE和出口PE之间有一个基于PIM的MDT。
图 4.
在SPT切换后，出口PE通过基于PIM的MDT将PIM加入消息发送到(S， G)的传统源PE。Egress-PE上的传入接口现在是mdtone。RP-PE不再是组播流量的周转路由器。
RP/0/RP1/CPU0:PE1#show mrib vrf one route 225.1.1.1
IP Multicast Routing Information Base
Entry flags: L - Domain-Local Source, E - External Source to the Domain,
C - Directly-Connected Check, S - Signal, IA - Inherit Accept,
IF - Inherit From, D - Drop, ME - MDT Encap, EID - Encap ID,
MD - MDT Decap, MT - MDT Threshold Crossed, MH - MDT interface handle
CD - Conditional Decap, MPLS - MPLS Decap, MF - MPLS Encap, EX - Extranet
MoFE - MoFRR Enabled, MoFS - MoFRR State, MoFP - MoFRR Primary
MoFB - MoFRR Backup, RPFID - RPF ID Set, X - VXLAN
Interface flags: F - Forward, A - Accept, IC - Internal Copy,
NS - Negate Signal, DP - Don't Preserve, SP - Signal Present,
II - Internal Interest, ID - Internal Disinterest, LI - Local Interest,
LD - Local Disinterest, DI - Decapsulation Interface
EI - Encapsulation Interface, MI - MDT Interface, LVIF - MPLS Encap,
EX - Extranet, A2 - Secondary Accept, MT - MDT Threshold Crossed,
MA - Data MDT Assigned, LMI - mLDP MDT Interface, TMI - P2MP-TE MDT Interface
IRMI - IR MDT Interface
(*,225.1.1.1) RPF nbr: 10.1.100.2 Flags: C RPF
Up: 00:09:59
Incoming Interface List
Lmdtone Flags: A LMI, Up: 00:09:59
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS, Up: 00:09:59
(10.2.3.10,225.1.1.1) RPF nbr: 10.1.100.3 Flags: RPF
Up: 00:14:29
Incoming Interface List
mdtone Flags: A MI, Up: 00:14:29
Outgoing Interface List
GigabitEthernet0/0/0/9 Flags: F NS, Up: 00:14:29
并且PE1具有源设备的以下PIM RPF信息：
RP/0/RP1/CPU0:PE1#show pim vrf one rpf 10.2.3.10
Table: IPv4-Unicast-default
* 10.2.3.10/32 [200/0]
via mdtone with rpf neighbor 10.1.100.3
RT:1:1 ,Connector: 1:3:10.1.100.3, Nexthop: 10.1.100.3
这意味着流量现在通过基于PIM的MDT从核心网络中的传统源PE直接流向出口PE。请参阅图 5。
图 5.
结论
所有非传统PE路由器（接收方PE或RP-PE路由器）必须具备迁移核心树协议和迁移C信令协议的配置。
或者，解决方法是确保SPT切换不会发生，但组播流量的路由可能不在网络核心中的最短路径上。
修订历史记录
| 版本 | 发布日期 | 备注 |
|---|---|---|
1.0 |
19-May-2021 |
初始版本 |
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