Configuring Centralized MAP-E
Centralized Scenario
In a centralized scenario, the MAP-BR and BRAS reside on different devices. The BRAS functions as a DHCPv6 server to deliver MAP addresses and mapping rules to MAP-CEs in DHCPv6 IA_PD mode. Router A functioning as the MAP-BR resides on the edge of a MAP domain and allows MAP-CEs to access the public IPv4 network through the IPv6 network that is within the MAP domain. The MAP-CEs use each other's public IPv4 address to communicate through the MAP-BR.
Configuration Roadmap
In the centralized scenario, MAP-E must be configured on the BRAS and MAP-BR.
Configuring a BRAS
Configuring a BMR
This section describes how to configure a basic mapping rule (BMR). Configure BMR rules on the BRAS to instruct the BRAS to assign IPv6 and IPv4 addresses to MAP-CEs.
Context
BMR parameters are configured using multiple commands in an instance. In addition to the IPv4 prefix and length of a MAP domain, the IPv6 prefix and length, and EA length, PSID offset can also be configured. The PSID offset can be used to reserve ports for public IP addresses.
Procedure
- Run system-view
The system view is displayed.
- Run map rule rule-name
The MAP rule view is displayed.
- Run rule-prefix ipv6–prefix prefix-length v6prefix-length ipv4–prefix ipv4–prefix prefix-length v4prefix-length [ vpn-instance vpn-instance-name ] ea-length ea-length [ psid-offset offset-length ]
The device is enabled to verify and encapsulate MAP packets.
A unique IPv6 address must be set in each BMR. The IPv6 addresses of BMRs cannot be identical. - Run commit
The configuration is committed.
Configuring a BR
A border relay (BR) is created. The MAP-CE encapsulates an IPv6 prefix defined based on the BR into traffic and directs the traffic to an interface board. The MAP-CE then selects a MAP-E instance to convert the traffic.
Configuring an IPv6 Delegation Prefix Pool
In a MAP-E or MAP-T scenario, a MAP rule needs to be bound to an IPv6 delegation prefix pool. The NE20E uses the BMR configured using the map-rule command to assign prefixes to MAP users.
Procedure
- Run system-view
The system view is configured.
- Run ipv6 prefix prefix-name delegation
An IPv6 delegation prefix pool is created, and the IPv6 delegation prefix pool view is displayed.
- Run map-rule rule-name
A MAP rule is bound to the IPv6 delegation prefix pool.
- Run commit
The configuration is committed.
Configuring an IPv6 Delegation Address Pool
In a MAP-E scenario, a prefix pool, a BR device name, and an FMR flag bit need to be configured in an IPv6 delegation address pool.
Procedure
- Run system-view
The system view is configured.
- Run ipv6 pool pool-name delegation
An IPv6 delegation address pool is created, and the IPv6 delegation address pool view is displayed.
- Run prefix prefix-name
An IPv6 prefix address is bound to the IPv6 delegation address pool.
- Run option-s46 br-ipv6-address br-address-nameNE20E
A DBR device name is bound to an IPv6 delegation address pool. The NE20E adds OPTION_S46_BR (option 90) to an IPv6 prefix in a DCHPv6 Response message to be sent to MAP-E users.
- (Optional) Run option-s46 fmr-flag disable
The F-flag bit is set to 0 in DHCPv6 OPTION_S46_RULE (option 89).
- Run commit
The configuration is committed.
Configuring a MAP-BR
Configuring a BMR
This section describes how to configure a basic mapping rule (BMR). A BMR is used to convert user-side IPv6 addresses into IPv4 addresses and network-side IPv4 addresses into IPv6 addresses.
Context
BMR parameters are set in an instance. The parameters include the IPv4 prefix and length, IPv6 prefix and length, embedded address length, and PSID offset. The PSID offset is used to reserve ports based on public IP addresses.
Procedure
- Run system-view
The system view is displayed.
- Run map rule rule-name
The MAP rule view is displayed.
- Run rule-prefix ipv6–prefix prefix-length v6prefix-length ipv4–prefix ipv4–prefix prefix-length v4prefix-length [ vpn-instance vpn-instance-name ] ea-length ea-length [ psid-offset offset-length ]
Parameters are configured to verify and encapsulate MAP packets.
A unique IPv6 address must be set in each BMR. The IPv6 addresses of BMRs cannot be identical. - Run commit
The configuration is committed.
Configuring a BR
A border relay (BR) is created. The MAP-CE encapsulates an IPv6 prefix defined based on the BR into traffic and directs the traffic to an interface board. The MAP-CE then selects a MAP-E instance to convert the traffic.
Binding a BR to a MAP-E Instance
This section describes how to bind a BR to a MAP-E instance so that a MAP-CE selects a MAP-E instance to convert IPv6 packets after MAP processing.
Binding a BMR to a MAP-E Instance
This section describes how to bind a BMR to a MAP-E instance. The BMR is used to encapsulate and verify packets in the MAP-E instance.
(Optional) Setting an MSS Value for MAP-E Services
The maximum segment size (MSS) value defined in TCP specifies the maximum length of a TCP packet to be sent without fragmentation. Two devices exchange SYN packets to negotiate the MSS value for a TCP connection to be established. If the size of packets for MAP processing is larger than a link MTU, the packets are fragmented. You can reduce the MSS value in TCP, which prevents a NAT board from fragmenting packets and helps improve MAP efficiency.
(Optional) Setting an MTU for IPv6 Packets
This section describes how to set a maximum transmission unit. Whether to fragment translated packets depends on the smaller value between the MTU configured in an instance and the interface MTU. To customize the MTU value of the IPv6 packets in a MAP instance, set the MTU value in the MAP instance.
(Optional) Setting the Traffic Class of IPv6 Packets
When an IPv4 packet is translated into an IPv6 packet, the Traffic-Class field value in the IPv6 packet is copied from the ToS field in the IPv4 packet. To modify the traffic class of IPv6 packets, set the traffic class value of IPv6 packets in an instance.
Procedure
- Run system-view
The system view is displayed.
- Run map-e instance instance-name [ id id ]
The MAP-E instance view is displayed.
- Run map traffic-class class-value
The Traffic-Class field is set for public network-to-private network IPv6 traffic.
By default, a device copies the IPv4 ToS field value and pastes it to the Traffic-Class field in IPv6 packets.
- Run commit
The configuration is committed.
Verifying the MAP-E Configuration
After configuring basic MAP-E functions, verify the configurations.
