组网需求
如图1所示：
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路由器PE1、P1、P2和PE2属于同一自治系统，要求它们之间通过IS-IS协议达到IPv6网络互连的目的。
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PE1、P1、P2和PE2属于IS-IS进程1，都是Level-2设备。
要求在PE1和PE2之间建立双向SRv6 BE路径，承载L3VPNv4业务。同时为了充分利用网络资源，要求PE1和PE2之间SRv6 BE承载的L3VPNv4业务可以进行等值负载分担（ECMP）。
图1 配置L3VPNv4 over SRv6 BE ECMP组网图
配置思路
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使能PE1、P1、P2和PE2各接口的IPv6转发能力，配置各接口的IPv6地址。
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在PE1、P1、P2和PE2上使能IS-IS，配置Level级别，指定网络实体。同时配置动态BFD for IPv6 IS-IS。
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在PE1和PE2上配置VPN实例。
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在PE和CE之间建立EBGP对等体关系。
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在PE之间建立MP-IBGP对等体关系。
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在PE1和PE2上配置SRv6。配置IS-IS的SRv6能力。
操作步骤
1. 使能各接口的IPv6转发能力，配置IPv6地址，以PE1为例，其他路由器的配置过程相同，不再赘述
<HUAWEI> system-view
[~HUAWEI] sysname PE1
[*HUAWEI] commit
[~PE1] interface gigabitethernet 1/0/0
[~PE1-GigabitEthernet1/0/0] ipv6 enable
[*PE1-GigabitEthernet1/0/0] ipv6 address 2001:db8:1::1 96
[*PE1-GigabitEthernet1/0/0] quit
[*PE1] interface gigabitethernet 2/0/0
[*PE1-GigabitEthernet2/0/0] ipv6 enable
[*PE1-GigabitEthernet2/0/0] ipv6 address 2001:db8:3::1 96
[*PE1-GigabitEthernet2/0/0] quit
[*PE1] interface LoopBack 1
[*PE1-LoopBack1] ipv6 enable
[*PE1-LoopBack1] ipv6 address 1::1 128
[*PE1-LoopBack1] quit
[*PE1] commit2. 配置IS-IS
配置IS-IS时，同时使能动态BFD功能，提高链路状态变化时IS-IS的收敛速度。
# 配置PE1。
[~PE1] bfd
[*PE1-bfd] quit
[*PE1] isis 1
[*PE1-isis-1] is-level level-2
[*PE1-isis-1] cost-style wide
[*PE1-isis-1] network-entity 10.0000.0000.0001.00
[*PE1-isis-1] ipv6 enable topology ipv6
[*PE1-isis-1] ipv6 bfd all-interfaces enable
[*PE1-isis-1] quit
[*PE1] interface gigabitethernet 1/0/0
[*PE1-GigabitEthernet1/0/0] isis ipv6 enable 1
[*PE1-GigabitEthernet1/0/0] quit
[*PE1] interface gigabitethernet 2/0/0
[*PE1-GigabitEthernet2/0/0] isis ipv6 enable 1
[*PE1-GigabitEthernet2/0/0] quit
[*PE1] interface loopback1
[*PE1-LoopBack1] isis ipv6 enable 1
[*PE1-LoopBack1] commit
[~PE1-LoopBack1] quit# 配置P1。
[~P1] bfd
[*P1-bfd] quit
[*P1] isis 1
[*P1-isis-1] is-level level-2
[*P1-isis-1] cost-style wide
[*P1-isis-1] network-entity 10.0000.0000.0002.00
[*P1-isis-1] ipv6 enable topology ipv6
[*P1-isis-1] ipv6 bfd all-interfaces enable
[*P1-isis-1] quit
[*P1] interface gigabitethernet 1/0/0
[*P1-GigabitEthernet1/0/0] isis ipv6 enable 1
[*P1-GigabitEthernet1/0/0] quit
[*P1] interface gigabitethernet 2/0/0
[*P1-GigabitEthernet2/0/0] isis ipv6 enable 1
[*P1-GigabitEthernet2/0/0] quit
[*P1] interface loopback1
[*P1-LoopBack1] isis ipv6 enable 1
[*P1-LoopBack1] commit
[~P1-LoopBack1] quit# 配置P2。
[~P2] bfd
[*P2-bfd] quit
[*P2] isis 1
[*P2-isis-1] is-level level-2
[*P2-isis-1] cost-style wide
[*P2-isis-1] network-entity 10.0000.0000.0004.00
[*P2-isis-1] ipv6 enable topology ipv6
[*P2-isis-1] ipv6 bfd all-interfaces enable
[*P2-isis-1] quit
[*P2] interface gigabitethernet 1/0/0
[*P2-GigabitEthernet1/0/0] isis ipv6 enable 1
[*P2-GigabitEthernet1/0/0] quit
[*P2] interface gigabitethernet 2/0/0
[*P2-GigabitEthernet2/0/0] isis ipv6 enable 1
[*P2-GigabitEthernet2/0/0] quit
[*P2] interface loopback1
[*P2-LoopBack1] isis ipv6 enable 1
[*P2-LoopBack1] commit
[~P2-LoopBack1] quit# 配置PE2。
[~PE2] bfd
[*PE2-bfd] quit
[*PE2] isis 1
[*PE2-isis-1] is-level level-2
[*PE2-isis-1] cost-style wide
[*PE2-isis-1] network-entity 10.0000.0000.0003.00
[*PE2-isis-1] ipv6 enable topology ipv6
[*PE2-isis-1] ipv6 bfd all-interfaces enable
[*PE2-isis-1] quit
[*PE2] interface gigabitethernet 1/0/0
[*PE2-GigabitEthernet1/0/0] isis ipv6 enable 1
[*PE2-GigabitEthernet1/0/0] quit
[*PE2] interface gigabitethernet 2/0/0
[*PE2-GigabitEthernet2/0/0] isis ipv6 enable 1
[*PE2-GigabitEthernet2/0/0] quit
[*PE2] interface loopback1
[*PE2-LoopBack1] isis ipv6 enable 1
[*PE2-LoopBack1] commit
[~PE2-LoopBack1] quit配置完成后，可按如下指导检查IS-IS是否配置成功。
# 显示IS-IS邻居信息。以PE1为例。
[~PE1] display isis peer
Peer information for ISIS(1)
System Id Interface Circuit Id State HoldTime Type PRI
--------------------------------------------------------------------------------
0000.0000.0004* GE2/0/0 0000.0000.0004.02 Up 7s L2 64
0000.0000.0002* GE1/0/0 0000.0000.0002.02 Up 9s L2 64
Total Peer(s): 2# 显示IS-IS路由表信息。以PE1为例。
[~PE1] display isis route
Route information for ISIS(1)
-----------------------------
ISIS(1) Level-2 Forwarding Table
--------------------------------
IPV6 Dest. ExitInterface NextHop Cost Flags
--------------------------------------------------------------------------------
1::/128 Loop1 Direct 0 D/-/L/-
2::/128 GE1/0/0 FE80::3A92:6CFF:FE31:307 10 A/-/-/-
3::/128 GE1/0/0 FE80::3A92:6CFF:FE31:307 20 A/-/-/-
GE2/0/0 FE80::3A92:6CFF:FE41:305
4::/128 GE2/0/0 FE80::3A92:6CFF:FE41:305 10 A/-/-/-
2001:DB8:1::/96 GE1/0/0 Direct 10 D/-/L/-
2001:DB8:2::/96 GE1/0/0 FE80::3A92:6CFF:FE31:307 20 A/-/-/-
2001:DB8:3::/96 GE2/0/0 Direct 10 D/-/L/-
2001:DB8:4::/96 GE2/0/0 FE80::3A92:6CFF:FE41:305 20 A/-/-/-
Flags: D-Direct, A-Added to URT, L-Advertised in LSPs, S-IGP Shortcut,
U-Up/Down Bit Set, LP-Local Prefix-Sid
Protect Type: L-Link Protect, N-Node Protect3. 在PE设备上配置使能IPv4地址族的VPN实例，将CE接入PE
# 配置PE1。
[~PE1] ip vpn-instance vpna
[*PE1-vpn-instance-vpna] ipv4-family
[*PE1-vpn-instance-vpna-af-ipv4] route-distinguisher 100:1
[*PE1-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*PE1-vpn-instance-vpna-af-ipv4] quit
[*PE1-vpn-instance-vpna] quit
[*PE1] interface gigabitethernet 3/0/0
[*PE1-GigabitEthernet3/0/0] ip binding vpn-instance vpna
[*PE1-GigabitEthernet3/0/0] ip address 10.1.1.1 24
[*PE1-GigabitEthernet3/0/0] quit
[*PE1] commit# 配置PE2。
[~PE2] ip vpn-instance vpna
[*PE2-vpn-instance-vpna] ipv4-family
[*PE2-vpn-instance-vpna-af-ipv4] route-distinguisher 200:1
[*PE2-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*PE2-vpn-instance-vpna-af-ipv4] quit
[*PE2-vpn-instance-vpna] quit
[*PE2] interface gigabitethernet 3/0/0
[*PE2-GigabitEthernet3/0/0] ip binding vpn-instance vpna
[*PE2-GigabitEthernet3/0/0] ip address 10.2.1.1 24
[*PE2-GigabitEthernet3/0/0] quit
[*PE2] commit# 按图1配置各CE的接口IP地址，配置过程请参见后面的配置文件。
配置完成后，在PE设备上执行display ip vpn-instance verbose命令可以看到VPN实例的配置情况。各PE能ping通自己接入的CE。
4. 在PE与CE之间建立EBGP对等体关系
# 配置CE1。
[~CE1] interface loopback 1
[*CE1-LoopBack1] ip address 11.11.11.11 32
[*CE1-LoopBack1] quit
[*CE1] bgp 65410
[*CE1-bgp] peer 10.1.1.1 as-number 100
[*CE1-bgp] network 11.11.11.11 32
[*CE1-bgp] quit
[*CE1] commit# 配置PE1。
[~PE1] bgp 100
[*PE1-bgp] router-id 1.1.1.1
[*PE1-bgp] ipv4-family vpn-instance vpna
[*PE1-bgp-vpna] peer 10.1.1.2 as-number 65410
[*PE1-bgp-vpna] import-route direct
[*PE1-bgp-vpna] commit
[~PE1-bgp-vpna] quit
[~PE1-bgp] quit# 配置CE2。
[~CE2] interface loopback 1
[*CE2-LoopBack1] ip address 22.22.22.22 32
[*CE2-LoopBack1] quit
[*CE2] bgp 65420
[*CE2-bgp] peer 10.2.1.1 as-number 100
[*CE2-bgp] network 22.22.22.22 32
[*CE2-bgp] quit
[*CE2] commit# 配置PE2。
[~PE2] bgp 100
[*PE2-bgp] router-id 2.2.2.2
[*PE2-bgp] ipv4-family vpn-instance vpna
[*PE2-bgp-vpna] peer 10.2.1.2 as-number 65420
[*PE2-bgp-vpna] import-route direct
[*PE2-bgp-vpna] commit
[~PE2-bgp-vpna] quit
[~PE2-bgp] quit配置完成后，在PE设备上执行display bgp vpnv4 vpn-instance peer命令，可以看到PE与CE之间的BGP对等体关系已建立，并达到Established状态。
以PE1与CE1的对等体关系为例：
[~PE1] display bgp vpnv4 vpn-instance vpna peer
BGP local router ID : 1.1.1.1
Local AS number : 100
VPN-Instance vpna, Router ID 1.1.1.1:
Total number of peers : 1 Peers in established state : 1
Peer V AS MsgRcvd MsgSent OutQ Up/Down State PrefRcv
10.1.1.2 4 65410 11 9 0 00:06:37 Established 15. 在PE之间建立MP-IBGP对等体关系
# 配置PE1。
[~PE1] bgp 100
[~PE1-bgp] peer 3::3 as-number 100
[*PE1-bgp] peer 3::3 connect-interface loopback 1
[*PE1-bgp] ipv4-family vpnv4
[*PE1-bgp-af-vpnv4] peer 3::3 enable
[*PE1-bgp-af-vpnv4] commit
[~PE1-bgp-af-vpnv4] quit
[~PE1-bgp] quit# 配置PE2。
[~PE2] bgp 100
[~PE2-bgp] peer 1::1 as-number 100
[*PE2-bgp] peer 1::1 connect-interface loopback 1
[*PE2-bgp] ipv4-family vpnv4
[*PE2-bgp-af-vpnv4] peer 1::1 enable
[*PE2-bgp-af-vpnv4] commit
[~PE2-bgp-af-vpnv4] quit
[~PE2-bgp] quit配置完成后，在PE设备上执行display bgp vpnv4 all peer命令，可以看到PE之间的BGP对等体关系已建立，并达到Established状态。
6. 在PE之间建立SRv6 BE路径
# 配置PE1。
[~PE1] segment-routing ipv6
[*PE1-segment-routing-ipv6] encapsulation source-address 1::1
[*PE1-segment-routing-ipv6] locator as1 ipv6-prefix 10:: 64 static 32
[*PE1-segment-routing-ipv6-locator] quit
[*PE1-segment-routing-ipv6] quit
[*PE1] bgp 100
[*PE1-bgp] ipv4-family vpnv4
[*PE1-bgp-af-vpnv4] peer 3::3 prefix-sid
[*PE1-bgp-af-vpnv4] quit
[*PE1-bgp] ipv4-family vpn-instance vpna
[*PE1-bgp-vpna] segment-routing ipv6 best-effort
[*PE1-bgp-vpna] segment-routing ipv6 locator as1
[*PE1-bgp-vpna] commit
[~PE1-bgp-vpna] quit
[~PE1-bgp] quit
[~PE1] isis 1
[~PE1-isis-1] segment-routing ipv6 locator as1
[*PE1-isis-1] commit
[~PE1-isis-1] quit# 配置PE2。
[~PE2] segment-routing ipv6
[*PE2-segment-routing-ipv6] encapsulation source-address 3::3
[*PE2-segment-routing-ipv6] locator as1 ipv6-prefix 30:: 64 static 32
[*PE2-segment-routing-ipv6-locator] quit
[*PE2-segment-routing-ipv6] quit
[*PE2] bgp 100
[*PE2-bgp] ipv4-family vpnv4
[*PE2-bgp-af-vpnv4] peer 1::1 prefix-sid
[*PE2-bgp-af-vpnv4] quit
[*PE2-bgp] ipv4-family vpn-instance vpna
[*PE2-bgp-vpna] segment-routing ipv6 best-effort
[*PE2-bgp-vpna] segment-routing ipv6 locator as1
[*PE2-bgp-vpna] commit
[~PE2-bgp-vpna] quit
[~PE2-bgp] quit
[~PE2] isis 1
[~PE2-isis-1] segment-routing ipv6 locator as1
[*PE2-isis-1] commit
[~PE2-isis-1] quit7. 检查配置结果
执行命令display ip routing-table vpn-instance vpna ip-address verbose查看VPN路由信息。以PE1的显示为例：
[~PE1] display ip routing-table vpn-instance vpna 22.22.22.22 32 verbose
Route Flags: R - relay, D - download to fib, T - to vpn-instance, B - black hole route
------------------------------------------------------------------------------
Routing Table : vpna
Summary Count : 1
Destination: 22.22.22.22/32
Protocol: IBGP Process ID: 0
Preference: 255 Cost: 0
NextHop: 30::1:0:20 Neighbour: 3::3
State: Active Adv Relied Age: 00h00m23s
Tag: 0 Priority: low
Label: 3 QoSInfo: 0x0
IndirectID: 0x10000C7 Instance:
RelayNextHop: 30::1:0:20 Interface: SRv6 BE
TunnelID: 0x0 Flags: RD从以上显示信息可以看出，VPN路由22.22.22.22/32迭代到SRv6 BE路径。
以路由下一跳30::1:0:20为目的地址查看IPv6路由的详细信息。
[~PE1] display ipv6 routing-table 30::1:0:20 verbose
Route Flags: R - relay, D - download to fib, T - to vpn-instance, B - black hole route
------------------------------------------------------------------------------
Routing Table : _public_
Summary Count : 2
Destination : 30:: PrefixLength : 64
NextHop : FE80::3A92:6CFF:FE31:307 Preference : 15
Neighbour : :: ProcessID : 1
Label : NULL Protocol : ISIS-L2
State : Active Adv Cost : 20
Entry ID : 0 EntryFlags : 0x00000000
Reference Cnt: 0 Tag : 0
Priority : medium Age : 132sec
IndirectID : 0x1000085 Instance :
RelayNextHop : :: TunnelID : 0x0
Interface : GigabitEthernet1/0/0 Flags : D
Destination : 30:: PrefixLength : 64
NextHop : FE80::3A92:6CFF:FE41:305 Preference : 15
Neighbour : :: ProcessID : 1
Label : NULL Protocol : ISIS-L2
State : Active Adv Cost : 20
Entry ID : 0 EntryFlags : 0x00000000
Reference Cnt: 0 Tag : 0
Priority : medium Age : 132sec
IndirectID : 0x1000087 Instance :
RelayNextHop : :: TunnelID : 0x0
Interface : GigabitEthernet2/0/0 Flags : D从以上显示信息可以看出，路由30::1:0:20具有两个出接口，转发时将形成ECMP。
同一VPN的CE能够相互Ping通，例如：
[~CE1] ping -a 11.11.11.11 22.22.22.22
PING 22.22.22.22: 56 data bytes, press CTRL_C to break
Reply from 22.22.22.22: bytes=56 Sequence=1 ttl=253 time=7 ms
Reply from 22.22.22.22: bytes=56 Sequence=2 ttl=253 time=5 ms
Reply from 22.22.22.22: bytes=56 Sequence=3 ttl=253 time=4 ms
Reply from 22.22.22.22: bytes=56 Sequence=4 ttl=253 time=5 ms
Reply from 22.22.22.22: bytes=56 Sequence=5 ttl=253 time=5 ms
--- 22.22.22.22 ping statistics ---
5 packet(s) transmitted
5 packet(s) received
0.00% packet loss
round-trip min/avg/max = 4/5/7 ms