Example: Load Balancing a 6rd Domain Across Multiple Service PICs

Hardware and Software Requirements

• An MX Series 3D Universal Edge router with a Services DPC with two available NPUs or an M Series Multiservice Edge router with two services PICs available for 6rd softwire concentrator processing.
• A domain name server (DNS)

• Junos OS Release 11.4 or higher.

Overview

Because of anticipated volume, a provider needs to balance 6rd softwire traffic between two services PICs.

Configuration

• Chassis Configuration
• Softwire Concentrator and Softwire Rule Configuration
• Stateful Firewall Configuration
• Service Set Configuration
• Load-Balancing Configuration

Chassis Configuration

Step-by-Step Procedure

1. Define the ingress interface and its properties.
   user@host# edit interfaces ge-1/2/0user@host# set unit 0 family inet address 10.10.10.1/16
2. Define the egress interface and its properties. In this example, the IPv6 clients try to reach the IPv6 server at 3abc::2/16.
3. Define the services PICs for selection as softwire concentrators by the load-balancing process. This configuration uses two PICs/NPUs: sp-3/0/0 and sp-3/1/0. A next-hop style service set is configured (shown in the next section).
   user@host# edit interfaces sp-3/0/0[edit interfaces ge-3/0/0]user@host# set services-options syslog host local services anyuser@host# set unit 0 family inetuser@host# set unit 0 family inet6user@host# set unit 1 family inet service-domain insideuser@host# set unit 1 family inet service-domain outsideuser@host# set unit 2 family inet service-domain insideuser@host# set unit 2 family inet service-domain outsideuser@host# up 1[edit]user@host# edit interfaces sp-3/1/0[edit interfaces sp-3/1/0]user@host# set services-options syslog host local services anyuser@host# set unit 0 family inetuser@host# set unit 0 family inet6user@host# set unit 1 family inet service-domain insideuser@host# set unit 1 family inet service-domain outsideuser@host# set unit 2 family inet service-domain insideuser@host# set unit 2 family inet service-domain outside

Softwire Concentrator and Softwire Rule Configuration

Step-by-Step Procedure

1. Go to the [edit services softwire] hierarchy level.
   user@host# edit services softwire
2. Configure IPv6 multicast.
   [edit services softwire]user@host# set ipv6-multicast-interfaces all
3. Go to the softtwire concentrator v6rd hierarchy level and name the softwire concentrator shenick01-rd1.
   [edit services softwire]user@host# edit softwire-concentrator v6rd shenick01-rd1
4. Configure the softwire concentrator properties.
   [edit services softwire softwire-concentrator v6rdshenick01-rd1 ]user@host# set softwire-address 30.30.30.1user@host# set ipv4-prefix 10.10.0.0/16user@host# set v6rd-prefix 3040::/16user@host# set mtu-v4 9192
5. Configure a softwire rule for incoming 6rd traffic.
   [edit services softwire softwire-concentrator v6rd shenick01-rd1 ]user@host# up 1[edit services softwire ]user@host# edit rule shenick01-r1[edit services softwire rule shenick01-r1]user@host# set match-direction inputuser@host# set term t1 then v6rd shenick01-rd1

Stateful Firewall Configuration

Step-by-Step Procedure

1. Go to the stateful firewall hierarchy level and define a rule.
   user@host# edit services stateful-firewall rule r1
2. Set the match direction.
   [edit services stateful-firewall rule r1]user@host# set match-direction input-output
3. Configure a term that accepts all traffic.
   [edit services stateful-firewall rule r1]user@host# set term t1 then accept

Service Set Configuration

Step-by-Step Procedure

1. Define a service set for the first NPU.
   user@host# edit services service-set v6rd-sset1
2. Configure the softwire and stateful firewall rules for the first NPU.
   [edit services service-set v6rd-sset1]user@host# set softwire-rules shenick01-r1user@host# set stateful-firewall-rules r1
3. Configure the inside and outside interfaces for the next-hop service.
   [edit services service-set v6rd-sset1]user@host# set next-hop-service inside-service-interface sp-3/0/0.1user@host# set next-hop-service outside-service-interface sp-3/0/0.2
4. Define a service set for the second NPU.
   user@host# edit services service-set v6rd-sset2
5. Configure the softwire and stateful firewall rules for the second NPU.
   [edit services service-set v6rd-sset2]user@host# set softwire-rules shenick01-r1user@host# set stateful-firewall-rules r1
6. Configure the inside and outside interfaces for the next-hop service.
   [edit services service-set v6rd-sset1]user@host# set next-hop-service inside-service-interface sp-3/1/0.1user@host# set next-hop-service outside-service-interface sp-3/1/0.2

Load-Balancing Configuration

Step-by-Step Procedure

1. Following the instructions below to complete the configuration

   Configure explicit routes and ECMP to load-balance the 6rd traffic. Explicit routes are configured for both the 6rd concentrator IPv4 address and the 6rd domain prefix, so that they point to both NPUs. In addition to these routes, the service PIC daemon (spd) also adds default routes to these addresses pointing to the NPUs. However, the routes added by the spd use different metrics, which are computed based on the FPC, PIC, slot numbers, and the subunit of the servics PIC if used in the service set configuration. The static routes configured in this sample configuration will have metrics of 5 and therefore a higher preference than the spd-added routes.

   rib inet6.0 {static {route 3040::0/16 next-hop [ sp-3/0/0.2 sp-3/1/0.2 ];}}static {route 30.30.30.1/32 next-hop [ sp-3/0/0.1 sp-3/1/0.1 ];}

   The explicitly configured routes are as follows:

   root@router# run show route 30.30.30.1

   inet.0: 37 destinations, 40 routes (36 active, 0 holddown, 1 hidden)
   + = Active Route, - = Last Active, * = Both
   
   30.30.30.1/32      *[Static/5] 00:00:10
                       > via sp-3/0/0.1
                         via sp-3/1/0.1
                       [Static/786433] 00:23:03
                       > via sp-3/0/0.1
                       [Static/851969] 00:00:09
                       > via sp-3/1/0.1
   

   root@router# run show route 3040::/16

   inet6.0: 20 destinations, 33 routes (20 active, 0 holddown, 0 hidden)
   + = Active Route, - = Last Active, * = Both
   
   3040::/16          *[Static/5] 00:00:15
                         via sp-3/0/0.2
                       > via sp-3/1/0.2
                       [Static/786434] 00:23:08
                       > via sp-3/0/0.2
                       [Static/851970] 00:00:14
                       > via sp-3/1/0.2
   

   Best Practice: The spd-installed routes have higher metric values (hence a low preference) and the metrics are different. If the metrics are different and ECMP is not enabled, even though multiple routes exist for the same destination, only one of the routes is picked up all the time (based on the metric). For ECMP you must configure equal-cost routes, and hence a manual configuration of routes is needed as shown above.

   Configuring ECMP

   Under the forwarding options, indicate to the router how to load-balance traffic by configuring the hash key as shown:

   user@host# show forwarding-options

   hash-key {
       family inet {  <== IPv4 traffic from CEs uses this
           layer-3 {
               destination-address;
               source-address;
           }
       }
       family inet6 {  <== IPv6 traffic from Internet uses this
           layer-3 {
               destination-address;
               source-address;
           }
       }
   }
   

   Tip: Both IPv4 and IPv6 hash keys must be configured. The IPv4 hash key is used to distribute the traffic coming from CPE devices to the 6rd BR. The IPv6 hash key is used to distribute the traffic coming from the IPv6 Internet to the 6rd domain. Note that since the hash in the forward and reverse direction is on different families, different flows from the same session can end up on different NPUs. However, since 6rd processing is stateless (as far as mapping IPv6 packets to softwires is concerned) this should not be a problem.