Example for Configuring an SRv6 SFC to Carry IPv4 Services (SFF-to-SF Packets Are Forwarded at Layer 3)

This section provides an example for configuring an SRv6 TE Policy to carry IPv4 services in an SRv6 SFC scenario (SFF-to-SF packets are forwarded at Layer 3).

Networking Requirements

In Figure 1, SF1 is dual-homed to SFF1 and SFF2, and has a bypass SF – SF2. For the IPv4 service flow direction from the SC to the tail end, it is required that the SRv6 SFC function be configured on the network, and IPv4 service reliability be ensured.

Figure 1 Configuring an SRv6 SFC to carry IPv4 services (SFF-to-SF packets are forwarded at Layer 3)

Interfaces 1 through 4 in this example represent GE 0/1/1, GE 0/1/2, GE 0/1/3, and GE 0/1/4, respectively.

Precautions

Before configuring an SRv6 SFC to carry IPv4 services (SFF-to-SF packets are forwarded at Layer 3), note the following:

The configuration in this example focuses on the SC, SFFs, and tail end. The configuration on the SFs is not mentioned.
Two locators are configured on SFF1, and on SFF2. Different locators are used to implement backup protection between SFF2 and SFF1, whereas the same locators are used to provide the anycast SID function on SFF1 and SFF2. The locator routes need to be advertised using IS-IS.
SF1 is dual-homed to SFF1 and SFF2. To implement dual-homing protection, the same End.AS SID must be configured on SFF1 and SFF2.

Configuration Roadmap

The configuration roadmap is as follows:

Enable IPv6 forwarding and configure an IPv6 address for each interface.
Enable IS-IS, configure an IS-IS level, and specify a network entity title (NET) on each device.
Configure basic SRv6 functions on each device.
Configure SF access on SFFs.
Configure SFC on SFFs.
Configure an SRv6 TE Policy on the SC.
Configure a traffic policy on the SC to redirect traffic to the SRv6 TE Policy.
Configure backup link protection and bypass protection on SFF1 and SFF2.
Configure one-arm BFD on SFF1 and SFF2 to detect SF1 reachability.

Data Preparation

To complete the configuration, you need the following data:

Interface IPv6 addresses on each device
IS-IS process ID of each device
IS-IS level of each device
Locators of each device

Procedure

Enable IPv6 forwarding and configure an IPv6 address for each interface.

# Configure SFF1. The configurations of other devices are similar to the configuration of SFF1. For configuration details, see Configuration Files in this section.

<HUAWEI> system-view
[~HUAWEI] sysname SFF1
[*HUAWEI] commit
[~SFF1] interface gigabitethernet 0/1/1
[~SFF1-GigabitEthernet0/1/1] ipv6 enable
[*SFF1-GigabitEthernet0/1/1] ipv6 address 2001:db8:1::2 96
[*SFF1-GigabitEthernet0/1/1] quit
[*SFF1] interface gigabitethernet 0/1/2
[*SFF1-GigabitEthernet0/1/2] ipv6 enable
[*SFF1-GigabitEthernet0/1/2] ipv6 address 2001:db8:2::1 96
[*SFF1-GigabitEthernet0/1/2] quit
[*SFF1] interface gigabitethernet 0/1/4
[*SFF1-GigabitEthernet0/1/4] ipv6 enable
[*SFF1-GigabitEthernet0/1/4] ipv6 address 2001:db8:6::1 96
[*SFF1-GigabitEthernet0/1/4] quit
[*SFF1] interface loopback1
[*SFF1-LoopBack1] ipv6 enable
[*SFF1-LoopBack1] ipv6 address 2::2 128
[*SFF1-LoopBack1] commit
[~SFF1-LoopBack1] quit

Configure IS-IS.

# Configure SFF1. The configurations of other devices are similar to the configuration of SFF1. For configuration details, see Configuration Files in this section.

[~SFF1] isis 1
[*SFF1-isis-1] is-level level-1
[*SFF1-isis-1] cost-style wide
[*SFF1-isis-1] network-entity 10.0000.0000.0002.00
[*SFF1-isis-1] ipv6 enable topology ipv6
[*SFF1-isis-1] quit
[*SFF1] interface gigabitethernet 0/1/1
[*SFF1-GigabitEthernet0/1/1] isis ipv6 enable 1
[*SFF1-GigabitEthernet0/1/1] quit
[*SFF1] interface gigabitethernet 0/1/2
[*SFF1-GigabitEthernet0/1/2] isis ipv6 enable 1
[*SFF1-GigabitEthernet0/1/2] quit
[*SFF1] interface gigabitethernet 0/1/4
[*SFF1-GigabitEthernet0/1/4] isis ipv6 enable 1
[*SFF1-GigabitEthernet0/1/4] quit
[*SFF1] interface loopback1
[*SFF1-LoopBack1] isis ipv6 enable 1
[*SFF1-LoopBack1] commit
[~SFF1-LoopBack1] quit

Configure SRv6 SIDs and enable IS-IS SRv6.

# Configure the SC.

[~SC] ip vpn-instance vpna
[*SC-vpn-instance-vpna] ipv4-family
[*SC-vpn-instance-vpna-af-ipv4] route-distinguisher 100:1
[*SC-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*SC-vpn-instance-vpna-af-ipv4] quit
[*SC-vpn-instance-vpna] quit
[*SC] segment-routing ipv6
[*SC-segment-routing-ipv6] encapsulation source-address 1::1
[*SC-segment-routing-ipv6] locator as1 ipv6-prefix 2001:db8:11:: 64 static 32
[*SC-segment-routing-ipv6-locator] opcode ::1 end psp
[*SC-segment-routing-ipv6-locator] opcode ::100 end-dt4 vpn-instance vpna
[*SC-segment-routing-ipv6-locator] quit
[*SC-segment-routing-ipv6] quit
[*SC] isis 1
[*SC-isis-1] segment-routing ipv6 locator as1 auto-sid-disable
[*SC-isis-1] commit
[~SC-isis-1] quit

# Configure SFF1.

[~SFF1] ip vpn-instance vpna
[*SFF1-vpn-instance-vpna] ipv4-family
[*SFF1-vpn-instance-vpna-af-ipv4] route-distinguisher 200:1
[*SFF1-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*SFF1-vpn-instance-vpna-af-ipv4] quit
[*SFF1-vpn-instance-vpna] quit
[*SFF1] segment-routing ipv6
[*SFF1-segment-routing-ipv6] encapsulation source-address 2::2
[*SFF1-segment-routing-ipv6] locator as1 ipv6-prefix 2001:db8:12:: 64 static 32
[*SFF1-segment-routing-ipv6-locator] opcode ::1 end psp
[*SFF1-segment-routing-ipv6-locator] quit
[*SFF1-segment-routing-ipv6] quit
[*SFF1] isis 1
[*SFF1-isis-1] segment-routing ipv6 locator as1 auto-sid-disable
[*SFF1-isis-1] commit
[~SFF1-isis-1] quit

# Configure SFF2.

[~SFF2] ip vpn-instance vpna
[*SFF2-vpn-instance-vpna] ipv4-family
[*SFF2-vpn-instance-vpna-af-ipv4] route-distinguisher 300:1
[*SFF2-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*SFF2-vpn-instance-vpna-af-ipv4] quit
[*SFF2-vpn-instance-vpna] quit
[*SFF2] segment-routing ipv6
[*SFF2-segment-routing-ipv6] encapsulation source-address 3::3
[*SFF2-segment-routing-ipv6] locator as1 ipv6-prefix 2001:db8:13:: 64 static 32
[*SFF2-segment-routing-ipv6-locator] opcode ::1 end psp
[*SFF2-segment-routing-ipv6-locator] quit
[*SFF2-segment-routing-ipv6] quit
[*SFF2] isis 1
[*SFF2-isis-1] segment-routing ipv6 locator as1 auto-sid-disable
[*SFF2-isis-1] commit
[~SFF2-isis-1] quit

# Configure SFF3.

[~SFF3] ip vpn-instance vpna
[*SFF3-vpn-instance-vpna] ipv4-family
[*SFF3-vpn-instance-vpna-af-ipv4] route-distinguisher 400:1
[*SFF3-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*SFF3-vpn-instance-vpna-af-ipv4] quit
[*SFF3-vpn-instance-vpna] quit
[*SFF3] segment-routing ipv6
[*SFF3-segment-routing-ipv6] encapsulation source-address 4::4
[*SFF3-segment-routing-ipv6] locator as1 ipv6-prefix 2001:db8:14:: 64 static 32
[*SFF3-segment-routing-ipv6-locator] opcode ::1 end psp
[*SFF3-segment-routing-ipv6-locator] quit
[*SFF3-segment-routing-ipv6] quit
[*SFF3] isis 1
[*SFF3-isis-1] segment-routing ipv6 locator as1 auto-sid-disable
[*SFF3-isis-1] commit
[~SFF3-isis-1] quit

# Configure the tail end.

[~Tail] ip vpn-instance vpna
[*Tail-vpn-instance-vpna] ipv4-family
[*Tail-vpn-instance-vpna-af-ipv4] route-distinguisher 500:1
[*Tail-vpn-instance-vpna-af-ipv4] vpn-target 111:1 both
[*Tail-vpn-instance-vpna-af-ipv4] quit
[*Tail-vpn-instance-vpna] quit
[*Tail] interface gigabitethernet 0/1/2
[*Tail-GigabitEthernet0/1/2] ip binding vpn-instance vpna
[*Tail-GigabitEthernet0/1/2] ip address 10.1.5.2 30
[*Tail-GigabitEthernet0/1/2] quit
[*Tail] segment-routing ipv6
[*Tail-segment-routing-ipv6] encapsulation source-address 5::5
[*Tail-segment-routing-ipv6] locator as1 ipv6-prefix 2001:db8:15:: 64 static 32
[*Tail-segment-routing-ipv6-locator] opcode ::1 end psp
[*Tail-segment-routing-ipv6-locator] opcode ::100 end-dt4 vpn-instance vpna
[*Tail-segment-routing-ipv6-locator] quit
[*Tail-segment-routing-ipv6] quit
[*Tail] isis 1
[*Tail-isis-1] segment-routing ipv6 locator as1 auto-sid-disable
[*Tail-isis-1] commit
[~Tail-isis-1] quit

After the configuration is complete, run the display segment-routing ipv6 locator [ locator-name ] verbose command to check SRv6 locator information.

Configure SF access on SFFs.

# Configure SFF1.

[~SFF1] bridge-domain 1
[*SFF1-bd1] quit
[*SFF1] interface gigabitethernet 0/1/3.1 mode l2
[*SFF1-GigabitEthernet0/1/3.1] encapsulation dot1q vid 1
[*SFF1-GigabitEthernet0/1/3.1] rewrite pop single
[*SFF1-GigabitEthernet0/1/3.1] bridge-domain 1
[*SFF1-GigabitEthernet0/1/3.1] quit
[*SFF1] interface Vbdif1
[*SFF1-Vbdif1] ip binding vpn-instance vpna
[*SFF1-Vbdif1] ip address 10.1.1.2 30
[*SFF1-Vbdif1] commit
[~SFF1-Vbdif1] quit

# Configure SFF2.

[~SFF2] bridge-domain 1
[*SFF2-bd1] quit
[*SFF2] interface gigabitethernet 0/1/3.1 mode l2
[*SFF2-GigabitEthernet0/1/3.1] encapsulation dot1q vid 1
[*SFF2-GigabitEthernet0/1/3.1] rewrite pop single
[*SFF2-GigabitEthernet0/1/3.1] bridge-domain 1
[*SFF2-GigabitEthernet0/1/3.1] quit
[*SFF2] interface Vbdif1
[*SFF2-Vbdif1] ip binding vpn-instance vpna
[*SFF2-Vbdif1] ip address 10.1.1.2 30
[*SFF2-Vbdif1] commit
[~SFF2-Vbdif1] quit

# Configure SFF3.

[~SFF3] bridge-domain 1
[*SFF3-bd1] quit
[*SFF3] interface gigabitethernet 0/1/3.1 mode l2
[*SFF3-GigabitEthernet0/1/3.1] encapsulation dot1q vid 1
[*SFF3-GigabitEthernet0/1/3.1] rewrite pop single
[*SFF3-GigabitEthernet0/1/3.1] bridge-domain 1
[*SFF3-GigabitEthernet0/1/3.1] quit
[*SFF3] interface Vbdif1
[*SFF3-Vbdif1] ip binding vpn-instance vpna
[*SFF3-Vbdif1] ip address 10.2.1.2 30
[*SFF3-Vbdif1] commit
[~SFF3-Vbdif1] quit

Configure basic SFC functions on SFFs.

# Configure SFF1.

[~SFF1] segment-routing ipv6
[~SFF1-segment-routing-ipv6] locator as2 ipv6-prefix 2001:db8:9999:: 64 static 32
[*SFF1-segment-routing-ipv6-locator] opcode ::1 end-as
[*SFF1-segment-routing-ipv6-locator-endas-::1] inner-type ipv4
[*SFF1-segment-routing-ipv6-locator-endas-::1] encapsulation ipv4 nexthop 10.1.1.1 out-interface Vbdif1 in-interface Vbdif1
[*SFF1-segment-routing-ipv6-locator-endas-::1] cache source-address 1::1
[*SFF1-segment-routing-ipv6-locator-endas-::1] cache list 2001:db8:15::100 2001:db8:15::1 2001:db8:9999::1
[*SFF1-segment-routing-ipv6-locator-endas-::1] quit
[*SFF1-segment-routing-ipv6-locator] quit
[*SFF1-segment-routing-ipv6] quit
[*SFF1] isis 1
[*SFF1-isis-1] segment-routing ipv6 locator as2 auto-sid-disable
[*SFF1-isis-1] commit
[~SFF1-isis-1] quit

# Configure SFF2.

[~SFF2] segment-routing ipv6
[~SFF2-segment-routing-ipv6] locator as2 ipv6-prefix 2001:db8:9999:: 64 static 32
[*SFF2-segment-routing-ipv6-locator] opcode ::1 end-as
[*SFF2-segment-routing-ipv6-locator-endas-::1] inner-type ipv4
[*SFF2-segment-routing-ipv6-locator-endas-::1] encapsulation ipv4 nexthop 10.1.1.1 out-interface Vbdif1 in-interface Vbdif1
[*SFF2-segment-routing-ipv6-locator-endas-::1] cache source-address 1::1
[*SFF2-segment-routing-ipv6-locator-endas-::1] cache list 2001:db8:15::100 2001:db8:15::1 2001:db8:9999::1
[*SFF2-segment-routing-ipv6-locator-endas-::1] quit
[*SFF2-segment-routing-ipv6-locator] quit
[*SFF2-segment-routing-ipv6] quit
[*SFF2] isis 1
[*SFF2-isis-1] segment-routing ipv6 locator as2 auto-sid-disable
[*SFF2-isis-1] commit
[~SFF2-isis-1] quit

# Configure SFF3.

[~SFF3] segment-routing ipv6
[~SFF3-segment-routing-ipv6] locator as2 ipv6-prefix 2001:db8:24:: 64 static 32
[*SFF3-segment-routing-ipv6-locator] opcode ::1 end-as
[*SFF3-segment-routing-ipv6-locator-endas-::1] inner-type ipv4
[*SFF3-segment-routing-ipv6-locator-endas-::1] encapsulation ipv4 nexthop 10.2.1.1 out-interface Vbdif1 in-interface Vbdif1
[*SFF3-segment-routing-ipv6-locator-endas-::1] cache source-address 1::1
[*SFF3-segment-routing-ipv6-locator-endas-::1] cache list 2001:db8:15::100 2001:db8:15::1 2001:db8:24::1
[*SFF3-segment-routing-ipv6-locator-endas-::1] quit
[*SFF3-segment-routing-ipv6-locator] quit
[*SFF3-segment-routing-ipv6] quit
[*SFF3] isis 1
[*SFF3-isis-1] segment-routing ipv6 locator as2 auto-sid-disable
[*SFF3-isis-1] commit
[~SFF3-isis-1] quit

Configure an SRv6 TE Policy on the SC.

# Configure the SC.

[~SC] segment-routing ipv6 
[~SC-segment-routing-ipv6] segment-list list1 
[*SC-segment-routing-ipv6-segment-list-list1] index 5 sid ipv6 2001:db8:9999::1
[*SC-segment-routing-ipv6-segment-list-list1] index 10 sid ipv6 2001:db8:15::1
[*SC-segment-routing-ipv6-segment-list-list1] commit
[~SC-segment-routing-ipv6-segment-list-list1] quit
[~SC-segment-routing-ipv6] srv6-te-policy locator as1 
[*SC-segment-routing-ipv6] srv6-te policy policy1 endpoint 5::5 color 101
[*SC-segment-routing-ipv6-policy-policy1] binding-sid 2001:db8:11::11
[*SC-segment-routing-ipv6-policy-policy1] candidate-path preference 100
[*SC-segment-routing-ipv6-policy-policy1-path] segment-list list1 
[*SC-segment-routing-ipv6-policy-policy1-path] commit
[~SC-segment-routing-ipv6-policy-policy1-path] quit
[~SC-segment-routing-ipv6-policy-policy1] quit
[~SC-segment-routing-ipv6] quit

After the configuration is complete, run the display srv6-te policy command to check SRv6 TE Policy information.

Configure a traffic policy on the SC to redirect traffic to the SRv6 TE Policy.

# Configure the SC.

[~SC] traffic classifier c1
[*SC-classifier-c1] if-match any
[*SC-classifier-c1] commit
[~SC-classifier-c1] quit
[~SC] traffic behavior b1
[*SC-behavior-b1] redirect srv6-te policy 5::5 101 vpnsid 2001:db8:15::100
[*SC-behavior-b1] commit
[~SC-behavior-b1] quit
[~SC] traffic policy p1
[*SC-trafficpolicy-p1] classifier c1 behavior b1
[*SC-trafficpolicy-p1] statistic enable
[*SC-trafficpolicy-p1] commit
[~SC-trafficpolicy-p1] quit
[~SC] bridge-domain 1
[*SC-bd1] quit
[*SC] interface gigabitethernet 0/1/1.1 mode l2
[*SC-GigabitEthernet0/1/1.1] encapsulation dot1q vid 1
[*SC-GigabitEthernet0/1/1.1] rewrite pop single
[*SC-GigabitEthernet0/1/1.1] bridge-domain 1
[*SC-GigabitEthernet0/1/1.1] quit
[*SC] interface Vbdif1
[*SC-Vbdif1] ip binding vpn-instance vpna
[*SC-Vbdif1] ip address 10.0.0.1 30
[*SC-Vbdif1] traffic-policy p1 inbound
[*SC-Vbdif1] commit
[~SC-Vbdif1] quit

Configure backup link protection and bypass protection on SFF1 and SFF2.

# Configure SFF1.

[~SFF1] segment-routing ipv6
[~SFF1-segment-routing-ipv6] proxy peer-sid 2001:db8:13::1
[*SFF1-segment-routing-ipv6] locator as2 
[*SFF1-segment-routing-ipv6-locator] opcode ::1 end-as
[*SFF1-segment-routing-ipv6-locator-endas-::1] backup-opcode ::2
[*SFF1-segment-routing-ipv6-locator-endas-::1] bypass sid 2001:db8:24::1
[*SFF1-segment-routing-ipv6-locator-endas-::1] quit
[*SFF1-segment-routing-ipv6-locator] quit
[*SFF1-segment-routing-ipv6] quit
[*SFF1] commit

# Configure SFF2.

[~SFF2] segment-routing ipv6
[~SFF2-segment-routing-ipv6] proxy peer-sid 2001:db8:12::1
[*SFF2-segment-routing-ipv6] locator as2 
[*SFF2-segment-routing-ipv6-locator] opcode ::1 end-as
[*SFF2-segment-routing-ipv6-locator-endas-::1] backup-opcode ::2
[*SFF2-segment-routing-ipv6-locator-endas-::1] bypass sid 2001:db8:24::1
[*SFF2-segment-routing-ipv6-locator-endas-::1] quit
[*SFF2-segment-routing-ipv6-locator] quit
[*SFF2-segment-routing-ipv6] quit
[*SFF2] commit

Configure one-arm BFD on SFF1 and SFF2.

# Configure SFF1.

[~SFF1] bfd
[*SFF1-bfd] quit
[*SFF1] bfd tosf1 bind peer-ip 10.1.1.1 vpn-instance vpna interface Vbdif1 one-arm-echo destination-ip 2.2.2.9
[*SFF1-bfd-session-tosf1] discriminator local 10 
[*SFF1-bfd-session-tosf1] process-pst 
[*SFF1-bfd-session-tosf1] commit
[~SFF1-bfd-session-tosf1] quit

# Configure SFF2.

[~SFF2] bfd
[*SFF2-bfd] quit
[*SFF2] bfd tosf1 bind peer-ip 10.1.1.1 vpn-instance vpna interface Vbdif1 one-arm-echo destination-ip 3.3.3.9
[*SFF2-bfd-session-tosf1] discriminator local 10 
[*SFF2-bfd-session-tosf1] process-pst 
[*SFF2-bfd-session-tosf1] commit
[~SFF2-bfd-session-tosf1] quit

Configuration Files

SC configuration file

#
sysname SC
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 100:1
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#               
segment-routing ipv6
 encapsulation source-address 1::1
 locator as1 ipv6-prefix 2001:db8:11:: 64 static 32 
  opcode ::1 end psp
  opcode ::100 end-dt4 vpn-instance vpna
 srv6-te-policy locator as1
 segment-list list1
  index 5 sid ipv6 2001:db8:9999::1
  index 10 sid ipv6 2001:db8:15::1
 srv6-te policy policy1 endpoint 5::5 color 101
  binding-sid 2001:db8:11::111
  candidate-path preference 100
   segment-list list1 
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0001.00
 #              
 ipv6 enable topology ipv6
 segment-routing ipv6 locator as1 auto-sid-disable
 #              
# 
bridge-domain 1
#
traffic classifier c1
 if-match any
#
traffic behavior b1
  redirect srv6-te policy 5::5 101 vpnsid 2001:db8:15::100
#
traffic policy p1
 classifier c1 behavior b1
 statistic enable
#
interface Vbdif1
 ip binding vpn-instance vpna
 ip address 10.0.0.1 255.255.255.252
 traffic-policy p1 inbound
#               
interface GigabitEthernet0/1/1
 undo shutdown  
#
interface GigabitEthernet0/1/1.1 mode l2
 encapsulation dot1q vid 1
 rewrite pop single
 bridge-domain 1
#               
interface GigabitEthernet0/1/2
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:1::1/96
 isis ipv6 enable 1
#
interface GigabitEthernet0/1/3
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:5::1/96
 isis ipv6 enable 1
#               
interface LoopBack1
 ipv6 enable    
 ipv6 address 1::1/128
 isis ipv6 enable 1
#                             
return

SFF1 configuration file

#
sysname SFF1
#
bfd 
#
bfd tosf1 bind peer-ip 10.1.1.1 vpn-instance vpna interface Vbdif1 one-arm-echo destination-ip 2.2.2.9
 discriminator local 10
 process-pst
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 200:1
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#               
segment-routing ipv6
 encapsulation source-address 2::2
 proxy peer-sid 2001:db8:13::1
 locator as1 ipv6-prefix 2001:db8:12:: 64 static 32
  opcode ::1 end psp
 locator as2 ipv6-prefix 2001:db8:9999:: 64 static 32
  opcode ::1 end-as
   inner-type ipv4
   encapsulation ipv4 nexthop 10.1.1.1 out-interface Vbdif1 in-interface Vbdif1
   cache source-address 1::1
   cache list 2001:db8:15::100 2001:db8:15::1 2001:db8:9999::1
   backup-opcode ::2
   bypass sid 2001:db8:24::1
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0002.00
 #              
 ipv6 enable topology ipv6
 segment-routing ipv6 locator as1 auto-sid-disable
 segment-routing ipv6 locator as2 auto-sid-disable
 #
# 
bridge-domain 1
#
interface Vbdif1
 ip binding vpn-instance vpna
 ip address 10.1.1.2 255.255.255.252
#               
interface GigabitEthernet0/1/1
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:1::2/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/2
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:2::1/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/3
 undo shutdown  
#
interface GigabitEthernet0/1/3.1 mode l2
 encapsulation dot1q vid 1
 rewrite pop single
 bridge-domain 1
#   
interface GigabitEthernet0/1/4
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:6::1/96
 isis ipv6 enable 1
#            
interface LoopBack1
 ipv6 enable    
 ipv6 address 2::2/128
 isis ipv6 enable 1
#               
return

SFF2 configuration file

#
sysname SFF2
#
bfd 
#
bfd tosf1 bind peer-ip 10.1.1.1 vpn-instance vpna interface Vbdif1 one-arm-echo destination-ip 3.3.3.9
 discriminator local 10
 process-pst
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 300:1
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#               
segment-routing ipv6
 encapsulation source-address 3::3
 proxy peer-sid 2001:db8:12::1
 locator as1 ipv6-prefix 2001:db8:13:: 64 static 32
  opcode ::1 end psp
 locator as2 ipv6-prefix 2001:db8:9999:: 64 static 32
  opcode ::1 end-as
   inner-type ipv4
   encapsulation ipv4 nexthop 10.1.1.1 out-interface Vbdif1 in-interface Vbdif1
   cache source-address 1::1
   cache list 2001:db8:15::100 2001:db8:15::1 2001:db8:9999::1
   backup-opcode ::2
   bypass sid 2001:db8:24::1
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0003.00
 #              
 ipv6 enable topology ipv6
 segment-routing ipv6 locator as1 auto-sid-disable
 segment-routing ipv6 locator as2 auto-sid-disable
 #              
# 
bridge-domain 1
#
interface Vbdif1
 ip binding vpn-instance vpna
 ip address 10.1.1.2 255.255.255.252
#               
interface GigabitEthernet0/1/1
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:2::2/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/2
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:3::1/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/3
 undo shutdown  
#
interface GigabitEthernet0/1/3.1 mode l2
 encapsulation dot1q vid 1
 rewrite pop single
 bridge-domain 1
#   
interface GigabitEthernet0/1/4
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:5::2/96
 isis ipv6 enable 1
#               
interface LoopBack1
 ipv6 enable    
 ipv6 address 3::3/128
 isis ipv6 enable 1
#               
return

SFF3 configuration file

#
sysname SFF3
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 400:1
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#               
segment-routing ipv6
 encapsulation source-address 4::4
 locator as1 ipv6-prefix 2001:db8:14:: 64 static 32
  opcode ::1 end psp
 locator as2 ipv6-prefix 2001:db8:24:: 64 static 32
  opcode ::1 end-as
   inner-type ipv4
   encapsulation ipv4 nexthop 10.2.1.1 out-interface Vbdif1 in-interface Vbdif1
   cache source-address 1::1
   cache list 2001:db8:15::100 2001:db8:15::1 2001:db8:24::1
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0004.00
 #              
 ipv6 enable topology ipv6
 segment-routing ipv6 locator as1 auto-sid-disable
 segment-routing ipv6 locator as2 auto-sid-disable
 #              
# 
bridge-domain 1
#
interface Vbdif1
 ip binding vpn-instance vpna
 ip address 10.2.1.2 255.255.255.252
#               
interface GigabitEthernet0/1/1
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:3::2/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/2
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:4::1/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/3
 undo shutdown  
#
interface GigabitEthernet0/1/3.1 mode l2
 encapsulation dot1q vid 1
 rewrite pop single
 bridge-domain 1
#   
interface GigabitEthernet0/1/4
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:6::2/96
 isis ipv6 enable 1
#               
interface LoopBack1
 ipv6 enable    
 ipv6 address 4::4/128
 isis ipv6 enable 1
#               
return

Tail end configuration file

#
sysname Tail
#
ip vpn-instance vpna
 ipv4-family
  route-distinguisher 500:1
  vpn-target 111:1 export-extcommunity
  vpn-target 111:1 import-extcommunity
#               
segment-routing ipv6
 encapsulation source-address 5::5
 locator as1 ipv6-prefix 2001:db8:15:: 64 static 32
  opcode ::1 end psp
  opcode ::100 end-dt4 vpn-instance vpna
#               
isis 1          
 is-level level-1
 cost-style wide
 network-entity 10.0000.0000.0005.00
 #              
 ipv6 enable topology ipv6
 segment-routing ipv6 locator as1 auto-sid-disable
 #              
#               
interface GigabitEthernet0/1/1
 undo shutdown  
 ipv6 enable    
 ipv6 address 2001:db8:4::2/96
 isis ipv6 enable 1
#               
interface GigabitEthernet0/1/2
 undo shutdown  
 ip binding vpn-instance vpna    
 ip address 10.5.1.2 255.255.255.252
#               
interface LoopBack1
 ipv6 enable    
 ipv6 address 5::5/64
 isis ipv6 enable 1
#               
return