1、在启用VRF前，需用sdm prefer routing extended-match命令调整TCAM（重启后生效），可以用show sdm prefer命令查看当前使用的template。
router#show sdm prefer
The current template is the routing extended-match template.
The selected template optimizes the resources in
the switch to support this level of features for
8 routed interfaces and 1K VLANs.
number of unicast mac addresses: 5K
number of igmp groups: 1K
number of qos aces: 512
number of security aces: 512
number of unicast routes: 8K
number of multicast routes: 1K
2、MVRF配置
ip vrf test
rd 100:1
route-target export 100:1
route-target import 100:1
ip multicast-routing
ip multicast-routing vrf test
ip pim vrf test rp-address 192.168.0.254
interface Vlan10
description "Uplink vlan"
ip vrf forwarding test
ip address 192.168.10.1 255.255.255.0
ip pim sparse-mode
interface Vlan100
description "Users Vlan"
ip vrf forwarding test
ip address 192.168.100.254 255.255.255.0
ip pim sparse-mode
3、问题处理
(1) 起初配置时，以为象Catalyst3750G一样，只需在VRF内启用multicast-routing，配置完成后，在 vlan100上配置ip igmp join-group 239.192.0.1命令测试组播，发现无法建立source Tree，相关命令查看信息如下（注：下述全部略去(*, 224.0.1.40)条目相关信息）：
router#show ip mroute vrf test
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,
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
V - RD & Vector, v - Vector
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.192.0.1), 00:02:55/00:02:36, RP 192.168.0.254, flags: SJCL
Incoming interface: Vlan10, RPF nbr 192.168.10.254
Outgoing interface list:
Vlan100, Forward/Sparse, 00:02:55/00:02:36
从上可以看出，mroute中无(S,G)条目，亦即未建立Source Tree。
router#show ip mroute vrf test count
IP Multicast Statistics
2 routes using 1140 bytes of memory
2 groups, 0.00 average sources per group
Forwarding Counts: Pkt Count/Pkts(neg(-) = Drops) per second/Avg Pkt Size/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)
Group: 239.192.0.1, Source count: 0, Packets forwarded: 0, Packets received: 0
router#show ip mroute vrf test active
Active IP Multicast Sources - sending >= 4 kbps
a negative (-) Rate counts pps being fast-dropped
router#show ip pim vrf test interface vlan 100 count
State: * - Fast Switched, D - Distributed Fast Switched
H - Hardware Switching Enabled
Address Interface FS Mpackets In/Out
192.168.100.254 Vlan100 * H 0/0
从上面几条命令显示结果可以看出，交换机并未接收到组播数据，即使mroute中有(*, 239.192.0.1)条目，并加入了RP-tree，但由于上级PE通过Source Tree发布组播数据，所以未收到。
(2) 全局配置ip multicast-routing命令后，mroute中就有了（S,G）条目，也能正常收到组播数据了。相关命令显示信息如下：
router#show ip mroute vrf test
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,
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
V - RD & Vector, v - Vector
Outgoing interface flags: H - Hardware switched, A - Assert winner
Timers: Uptime/Expires
Interface state: Interface, Next-Hop or VCD, State/Mode
(*, 239.192.0.1), 00:15:17/stopped, RP 192.168.0.254, flags: SJCL
Incoming interface: Vlan10, RPF nbr 192.168.10.254
Outgoing interface list:
Vlan100, Forward/Sparse, 00:15:17/00:02:19
(192.168.1.1, 239.192.0.1), 00:00:07/00:02:59, flags: LJT
Incoming interface: Vlan10, RPF nbr 192.168.10.254
Outgoing interface list:
Vlan100, Forward/Sparse, 00:00:07/00:02:52
router#show ip mroute vrf test active
Active IP Multicast Sources - sending >= 4 kbps
a negative (-) Rate counts pps being fast-dropped
Group: 239.192.0.1, (?)
Source: 192.168.1.1 (?)
Rate: 295 pps/3131 kbps(1sec), 2984 kbps(last 40 secs), 3269 kbps(life avg)
router#show ip mroute vrf test count
IP Multicast Statistics
3 routes using 1604 bytes of memory
2 groups, 0.50 average sources per group
Forwarding Counts: Pkt Count/Pkts(neg(-) = Drops) per second/Avg Pkt Size/Kilobits per second
Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)
Group: 239.192.0.1, Source count: 1, Packets forwarded: 18648, Packets received: 18648
RP-tree: Forwarding: 0/0/0/0, Other: 0/0/0
Source: 192.168.1.1/32, Forwarding: 18648/288/1325/3055, Other: 18648/0/0
router#show ip pim vrf test interface vlan 100 count
State: * - Fast Switched, D - Distributed Fast Switched
H - Hardware Switching Enabled
Address Interface FS Mpackets In/Out
192.168.100.254 Vlan100 * H 0/31119