Configuring Public IPv4 over SRv6 BE

This section describes how to configure public IPv4 over SRv6 BE.

Usage Scenario

Public IPv4 over SRv6 BE allows SRv6 BE paths on a public network to carry public network IPv4 services. The implementation of public IPv4 over SRv6 BE involves establishing SRv6 BE paths, advertising BGP routes, and forwarding data. As shown in Figure 1, PE1 and PE2 communicate through an IPv6 public network. An SRv6 BE path can be deployed on the IPv6 public network to carry public network IPv4 services.

Figure 1 Public IPv4 over SRv6 BE networking

Pre-configuration Tasks

Before configuring public IPv4 over SRv6 BE, complete the following tasks:

Configure a link layer protocol.
Configure network-layer addresses for interfaces to ensure that neighboring devices are reachable at the network layer.

Procedure

Configure IPv6 IS-IS on each PE and P. For configuration details, see Configuring Basic IPv6 IS-IS Functions.
Establish an EBGP peer relationship between PE1 and DeviceA and another one between PE2 and DeviceB.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run router-id ipv4-address
  A BGP router ID is configured.
4. Run peer ipv4-address as-number as-number
  The IPv4 address of a peer and the number of the AS where the peer resides are specified.
5. Run ipv4-family unicast
  The BGP-IPv4 unicast address family view is displayed.
6. Run peer ipv4-address enable
  The device is enabled to exchange routing information with the specified IPv4 peer.
7. Run commit
  The configuration is committed.
8. Run quit
  Exit the BGP-IPv4 unicast address family view.
9. Run quit
  Exit the BGP view.
Establish an MP-IBGP peer relationship between the PEs.
1. Run bgp as-number
  The BGP view is displayed.
2. Run router-id ipv4-address
  A BGP router ID is configured.
3. Run peer ipv6-address as-number as-number
  The IPv6 address of a peer and the number of the AS where the peer resides are specified.
4. Run peer ipv6-address connect-interface interface-type interface-number
  A source interface and a source address are specified for TCP connection setup.
5. Run ipv4-family unicast
  The BGP-IPv4 unicast address family view is displayed.
6. Run peer ipv6-address enable
  The device is enabled to exchange routing information with the specified IPv6 peer.
7. Run commit
  The configuration is committed.
8. Run quit
  Exit the BGP-IPv4 unicast address family view.
9. Run quit
  Exit the BGP view.
Configure basic SRv6 functions.
1. Run segment-routing ipv6
  SRv6 is enabled, and the SRv6 view is displayed.
2. Run encapsulation source-address ipv6-address [ ip-ttl ttl-value ]
  A source address is specified for SRv6 encapsulation.
3. Run locator locator-name [ ipv6-prefix ipv6-address prefix-length [ static static-length | args args-length ] ^* ]
  An SRv6 locator is configured.
4. (Optional) Run opcode func-opcode end-dt4
  A static SID opcode is configured.
  
  An End.DT4 SID can be either dynamically allocated through BGP or manually configured. If a dynamically allocated SID and a manually configured SID both exist, the manually configured SID takes effect. If you want to enable dynamic End.DT4 SID allocation using the segment-routing ipv6 locator locator-name command, skip this step.
5. Run quit
  Exit the SRv6 locator view.
6. Run quit
  Exit the SRv6 view.
Enable IS-IS SRv6.
1. Run isis [ process-id ]
  The IS-IS view is displayed.
2. Run ipv6 enable topology ipv6
  IPv6 is enabled for the IS-IS process in the IPv6 topology.
3. Run segment-routing ipv6 locator locator-name [ auto-sid-disable ]
  IS-IS SRv6 is enabled.
4. Run quit
  Exit the IS-IS view.
Configure public network routes on PEs to carry SIDs and recurse to SRv6 BE paths based on the SIDs.
1. Run bgp { as-number-plain | as-number-dot }
  The BGP view is displayed.
2. Run ipv4-family unicast
  The BGP-IPv4 unicast address family view is displayed.
3. Run peer ipv6-address prefix-sid [ advertise-srv6-locator ]
  The device is enabled to exchange prefix SIDs with the specified peer.
  
  In a scenario where BFD is used to check locator reachability and the P nodes between local and remote PEs summarize locator routes, you can specify the advertise-srv6-locator parameter to enable PE-advertised BGP routes to carry locator length information. In this way, when the peer IPv6 address bound to the BFD session matches the locator's IPv6 address, locator reachability can be checked using BFD to complete auto FRR path switching.
4. Run segment-routing ipv6 best-effort
  The device is enabled to perform public route recursion based on the SIDs carried by routes.
5. Run segment-routing ipv6 locator locator-name
  The device is enabled to add SIDs to public routes.
6. (Optional) Run segment-routing ipv6 apply-sid per-nexthop pop-go
  The device is configured to allocate SIDs to IPv4 unicast routes received from public IPv4 peers based on next hops.
7. Run commit
  The configuration is committed.

Verifying the Configuration

After configuring public IPv4 over SRv6 BE, verify the configuration.

Run the display bgp routing-table ipv4-address [ mask | mask-length ] command to check BGP IPv4 routing table information.
Run the display segment-routing ipv6 locator [ locator-name ] verbose command to check SRv6 locator information.
Run the display segment-routing ipv6 local-sid [ locator-name ] forwarding command to check information about the SRv6 local SID table.