Route health injection

The Route Health Injection (RHI) module monitors your load balancer’s connectivity to backend servers and has the ability to remove the entire load balancer from duty if the load balancer can suddenly not reach those servers. The idea is that if a load balancer can’t reach the servers, and you’re running an active/active load balancer pair, then you can deactive the problematic load balancer and route all traffic to the other, healthy load balancer.

The RHI module is meant to work with IP routing protocols, such as BGP and OSPF, configured for Equal-cost multi-path (ECMP) routing. ECMP enables the network to route traffic to a destination over multiple paths, allowing you to relay IP packets to both of your load balancers in parallel. The ability to detect problems and route traffic away from unhealthy load balancers is important for making ECMP resilient.

Concepts Jump to heading

This section describes the concepts behind route health injection combined with ECMP.

How ECMP routing works Jump to heading

Your router attempts to send packets to their destination using the most efficient network path. When two network paths have identical costs, meaning they are equally good, then the router can load balance traffic across both paths given that it supports ECMP. With ECMP, you can configure the router to see both of your load balancers as being different, but equal, routes to the destination IP address. So the router can send traffic to both load balancers in parallel, achieving high availiability.

How do the two load balancers present themselves to the router as being routes of equal costs? They present routes to the same IP address as passing through themselves and inject those routes into the router’s routing table. In essence, they become gateways for reaching the same IP address.

A router on the 192.168.0.0/24 network sees:

Destination address	Route via
`192.168.1.10`	* Load balancer 1 at `192.168.0.101` or * Load balancer 2 at `192.168.0.102`

The RHI module shares routes with the router. It does this by installing BIRD Internet Routing Daemon, which is open-source software, onto the load balancer. BIRD shares routes by using either the BGP or OSPF protocol.

While to the router it looks as through the load balancers are simply the next hop towards the destination, actually the load balancers are the final hop. They own the destination IP address. Having both load balancers bound to the same IP address could cause conflicts on the network, though. Two ways to solve this problem that we’ll cover are:

Add a second address to the load balancer’s loopback network interface and disable ARP so that this address isn’t advertised on the network. That way, only the load balancer sees this address and essentially sends the traffic to itself.
Intercept traffic destined for a non-locally bound address by configuring transparent proxying.

How Route Health Injection works Jump to heading

The RHI module adds this load balancer as a route in BIRD’s configuration using a custom routing table named volatile. BIRD then broadcasts these routes to peer routers using the BGP or OSPF protocol. If either a frontend or a backend is down, then the RHI module removes the route from the volatile table, notifying BIRD to stop advertising this load balancer as a route on the network, diverting the flow of traffic to the other load balancer in the active/active cluster. You can configure ECMP on your router to load balance traffic to both load balancers via the advertised routes.

Prerequisities Jump to heading

Ensure that you’ve met the following prerequisites:

Your router has enabled ECMP. Consult your router’s documentation for details.

Install and configure RHI Jump to heading

In this section, you will learn how to set up route health injection.

Install the RHI module Jump to heading

To install the RHI module, perform these steps on each load balancer:

Install the RHI module using your package manager:

nix
sudo apt-get install hapee-extras-rhi

nix
sudo apt-get install hapee-extras-rhi

nix
sudo yum install hapee-extras-rhi

nix
sudo yum install hapee-extras-rhi

nix
sudo zypper install hapee-extras-rhi

nix
sudo zypper install hapee-extras-rhi

nix
sudo pkg install hapee-extras-rhi

nix
sudo pkg install hapee-extras-rhi

This installs the hapee-extras-route package too, which is our version of the BIRD Internet Routing Daemon. The daemon is stored as /opt/hapee-extras/sbin/hapee-route.

Create a socket for the Runtime API.

The RHI module needs to connect to the Runtime API to collect information about the health of your frontends and backends. Add a new stats socket line to the global section of your HAProxy Enterprise configuration. This exposes the Runtime API as the socket /var/run/hapee-extras/hapee-lb.sock:
```
hapee-lb.cfg
haproxy
global
  stats socket /var/run/hapee-extras/hapee-lb.sock user hapee-lb group hapee mode 660
```
```
hapee-lb.cfg
haproxy
global
  stats socket /var/run/hapee-extras/hapee-lb.sock user hapee-lb group hapee mode 660
```
Use the correct socket path

Your load balancer configuration likely contains a stats socket line in the global section already, but if it isn’t using the file path shown here, add a second stats socket line or else it won’t work.
Optional: Change the socket path

The RHI module expects the Runtime API socket to be /var/run/hapee-extras/hapee-lb.sock. However, you can change the path that the RHI module expects by setting the variable HAPEE_LB_SOCKET in the following file:
- On Debian/Ubuntu: /etc/default/hapee-extras-rhi
- On RHEL: /etc/sysconfig/hapee-extras-rhi
For example:
```
hapee-extras-rhi
text
HAPEE_LB_SOCKET="/var/run/hapee-3.0/hapee-lb.sock"
```
```
hapee-extras-rhi
text
HAPEE_LB_SOCKET="/var/run/hapee-3.0/hapee-lb.sock"
```
Still, you must ensure that this same path is configured in your HAProxy Enterprise configuration file:
```
hapee-lb.cfg
haproxy
global
  stats socket /var/run/hapee-3.0/hapee-lb.sock user hapee-lb group hapee mode 660
```
```
hapee-lb.cfg
haproxy
global
  stats socket /var/run/hapee-3.0/hapee-lb.sock user hapee-lb group hapee mode 660
```

Configure route health injection Jump to heading

To configure the RHI module to share routes with your router:

Edit the file /etc/hapee-extras/hapee-rhi.cfg. The default configuration contains an example:
```
hapee-rhi.cfg
text
# Inject the 10.200.200.200/32 address into the route daemon if
# all the backends "be_static" and "be_app" are up.
10.200.200.200/32 = all(b:be_static,b:be_app)
```
```
hapee-rhi.cfg
text
# Inject the 10.200.200.200/32 address into the route daemon if
# all the backends "be_static" and "be_app" are up.
10.200.200.200/32 = all(b:be_static,b:be_app)
```
This file contains a list of routes that the RHI module will add to BIRD’s volatile table, but only if the given rule returns true. A rule checks the status of one or more frontends or backends to see if they are up or down. A backend is treated as down if all servers fail their health checks or if you manually disable the servers. A frontend is down if you disable it manually.

In this example, the rule uses all function to announce the 192.168.1.10/32 IP address only when both the be_static and be_app backend are up and running. When the condition is false, the IP address is removed from the list of advertised routes.

Let’s look at another example. The following line uses the any function to advertise the IP if either the be_app or be_app2 backends are up and running:
```
hapee-rhi.cfg
text
192.168.1.10/32 = any(b:be_app,b:be_app2)
```
```
hapee-rhi.cfg
text
192.168.1.10/32 = any(b:be_app,b:be_app2)
```

After making changes to the hapee-rhi.cfg file, save the file. Then enable and restart the service:

nix
sudo systemctl enable hapee-extras-rhi
sudo systemctl restart hapee-extras-rhi

nix
sudo systemctl enable hapee-extras-rhi
sudo systemctl restart hapee-extras-rhi

To configure BIRD for BGP or OSPF, which are used to advertise routes to peer routers, edit the file /etc/hapee-extras/hapee-route.cfg.

Add a section for either BGP or OSPF, depending on which protocol you intend to use for advertising routes to peers.

Use BGP

An example BGP configuration section:

hapee-route.cfg
text
  protocol bgp r1 {
  local 192.168.0.101 as 65001;
  neighbor 192.168.0.1 as 65001;
  graceful restart on;
  import none;
  
  # advertise the IP route
  export where proto = "vol1";
  }

hapee-route.cfg
text
  protocol bgp r1 {
  local 192.168.0.101 as 65001;
  neighbor 192.168.0.1 as 65001;
  graceful restart on;
  import none;
  
  # advertise the IP route
  export where proto = "vol1";
  }

In this example:

The local directive refers to the IP address assigned to this load balancer’s network interface and assigns the Autonomous System Number 65001.
The neighbor directive refers to the layer 3 device, such as the gateway router, with which we are establishing a BGP session.
The export line advertises routes from the volatile table, vol1.

Use OSPF

An example OSPF configuration section:

hapee-route.cfg
text
protocol ospf anycast {
  tick 2;
  import none;
  
  # advertise the IP route
  export where proto = "vol1";
  
  area 0.0.0.0 {
    stub no;
    interface "eth0" {
       hello 10;
       retransmit 6;
       cost 10;
       transmit delay 5;
       dead count 4;
       wait 50;
       type broadcast;
    };
  };
}

hapee-route.cfg
text
protocol ospf anycast {
  tick 2;
  import none;
  
  # advertise the IP route
  export where proto = "vol1";
  
  area 0.0.0.0 {
    stub no;
    interface "eth0" {
       hello 10;
       retransmit 6;
       cost 10;
       transmit delay 5;
       dead count 4;
       wait 50;
       type broadcast;
    };
  };
}

The export line advertises routes from the volatile table, vol1.

After making changes to the hapee-route.cfg file, save the file. Then restart the service:

nix
sudo systemctl restart hapee-extras-route

nix
sudo systemctl restart hapee-extras-route

Optional: To advertise IPv6 routes, repeat these steps for the hapee-extras-route6 service.

Verify that RHI added a route to BIRD by calling the show route command. The IP should display.

nix
sudo /opt/hapee-extras/bin/hapee-route-cli show route

nix
sudo /opt/hapee-extras/bin/hapee-route-cli show route

output
text
BIRD 1.6.3 ready.
192.168.1.10/32    dev auto [vol1 18:54:15] * (0)

output
text
BIRD 1.6.3 ready.
192.168.1.10/32    dev auto [vol1 18:54:15] * (0)

When you disable all servers in the backend, the command should not return this route.

Intercept traffic destined for the IP Jump to heading

Remember that both of your load balancers must be able to receive packets at the same IP address defined in the route shared with your router, for example 192.168.1.10/32, but without causing a conflict on the network. Here are two ways to accomplish that:

Add a second address to the load balancer's loopback network interface

The IP must be handled on each server’s loopback interface to accept connections, but can’t be advertised on the network or it will be identified as an IP conflict by some network components. To avoid IP address conflicts, disable ARP for IP addresses managed by the loopback interface.

Perform these steps on both load balancers:

Edit the HAProxy Enterprise configuration file, /etc/hapee-3.0/hapee-lb.cfg:
```
hapee-lb.cfg
haproxy
frontend www
  bind 192.168.1.10:80 name http
  bind 192.168.1.10:443 name https ssl crt site.pem
```
```
hapee-lb.cfg
haproxy
frontend www
  bind 192.168.1.10:80 name http
  bind 192.168.1.10:443 name https ssl crt site.pem
```
- In the frontend section, define one or more bind lines that listen at the IP address you created a route for, such as 192.168.1.10. This address should not be assigned to any network interfaces.
- Each load balancer should be assigned the same IP address.

Save the changes and then reload the service.

nix
sudo systemctl reload hapee-3.0-lb

nix
sudo systemctl reload hapee-3.0-lb

Manage the IP address through a loopback interface.

Edit the file /etc/network/interfaces. Add a new iface section for the lo interface and add the address under it:

interfaces
text
# The loopback network interface
auto lo
iface lo inet loopback
iface lo inet static
  address 192.168.1.10/32

interfaces
text
# The loopback network interface
auto lo
iface lo inet loopback
iface lo inet static
  address 192.168.1.10/32

Edit the netplan YAML configuration file located in /etc/netplan. The configuration file is probably the one having the lowest number and has a name like 00-installer-config.yaml or 01-netcfg.yaml.

Edit the netplan YAML file, adding an lo section under the ethernets level:

01-netcfg.yaml
yaml
network:
  ethernets:
    lo:
      dhcp4: false
      addresses:
      - "192.168.1.10/32"

01-netcfg.yaml
yaml
network:
  ethernets:
    lo:
      dhcp4: false
      addresses:
      - "192.168.1.10/32"

Then use sudo netplan try and sudo netplan apply before rebooting to make sure the configuration is valid. Ignore warnings about Open vSwitch.

To persist the IP address on RHEL 9.2 or newer, use NetworkManager. Previous versions did not support managing the loopback interface with NetworkManager.

nix
sudo nmcli connection modify lo +ipv4.addresses 192.168.1.10/32
sudo nmcli con up 'lo'

nix
sudo nmcli connection modify lo +ipv4.addresses 192.168.1.10/32
sudo nmcli con up 'lo'

To persist the IP address on RHEL systems older than 9.2, create a new service for loading it at boot:

nix
sudo touch /etc/systemd/system/01-static-ip.service
sudo vi /etc/systemd/system/01-static-ip.service

nix
sudo touch /etc/systemd/system/01-static-ip.service
sudo vi /etc/systemd/system/01-static-ip.service

Add the following lines to the service file:

01-static-ip.service
text
[Unit]
Description=Add static IP to loopback
Wants=network-online.target
After=network-online.target
[Service]
Type=oneshot
# create the address
ExecStart=-/usr/sbin/ip address add 192.168.1.10/32 dev lo
[Install]
WantedBy=multi-user.target

01-static-ip.service
text
[Unit]
Description=Add static IP to loopback
Wants=network-online.target
After=network-online.target
[Service]
Type=oneshot
# create the address
ExecStart=-/usr/sbin/ip address add 192.168.1.10/32 dev lo
[Install]
WantedBy=multi-user.target

Set the service to start on boot:

nix
sudo systemctl enable 01-static-ip.service

nix
sudo systemctl enable 01-static-ip.service

Add the following lines to /etc/sysctl.conf.

text
net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.all.arp_announce=2

text
net.ipv4.conf.all.arp_ignore=1
net.ipv4.conf.all.arp_announce=2

Restart the HAProxy Enterprise server.

Configure transparent proxying

Perfom these steps on both load balancers to enable transparent proxying:

Edit the HAProxy Enterprise configuration file, /etc/hapee-3.0/hapee-lb.cfg:
```
hapee-lb.cfg
haproxy
frontend www
  bind 192.168.1.10:80 name http transparent
  bind 192.168.1.10:443 name https ssl crt site.pem transparent
```
```
hapee-lb.cfg
haproxy
frontend www
  bind 192.168.1.10:80 name http transparent
  bind 192.168.1.10:443 name https ssl crt site.pem transparent
```
- In the frontend section, define one or more bind lines that listen at the IP address you created a route for, such as 192.168.1.10. This address should not be assigned to any network interfaces.
- Because the IP address is not configured on the network interface, add the transparent argument. This indicates that the IP address should be bound even though it does not belong to the local machine. Packets targeting this address will be intercepted as if the address were locally configured. This feature uses the Linux kernel’s TPROXY feature.
- Each load balancer should be assigned the same IP address.

Save the changes and then reload the service.

nix
sudo systemctl reload hapee-3.0-lb

nix
sudo systemctl reload hapee-3.0-lb

Add firewall rules that intercept packets that have a destination IP address matching a listening socket, which in this case is our transparent proxied IP address. Also add policy-based routing rules to deliver the traffic locally.

Create firewall and routing rules:

nix
sudo iptables -t mangle -N DIVERT
sudo iptables -t mangle -A PREROUTING -p tcp -m socket -j DIVERT
sudo iptables -t mangle -A PREROUTING -p udp -m socket -j DIVERT
sudo iptables -t mangle -A DIVERT -j MARK --set-mark 1
sudo iptables -t mangle -A DIVERT -j ACCEPT
sudo ip rule add fwmark 1 lookup 100
sudo ip route add local 0.0.0.0/0 dev lo table 100

nix
sudo iptables -t mangle -N DIVERT
sudo iptables -t mangle -A PREROUTING -p tcp -m socket -j DIVERT
sudo iptables -t mangle -A PREROUTING -p udp -m socket -j DIVERT
sudo iptables -t mangle -A DIVERT -j MARK --set-mark 1
sudo iptables -t mangle -A DIVERT -j ACCEPT
sudo ip rule add fwmark 1 lookup 100
sudo ip route add local 0.0.0.0/0 dev lo table 100

To make the iptables changes persistent after reboot, use the iptables-save command. It saves the changes and configures the system to restore them at reboot.

nix
sudo apt install iptables-persistent
sudo su -c 'iptables-save > /etc/iptables/rules.v4'

nix
sudo apt install iptables-persistent
sudo su -c 'iptables-save > /etc/iptables/rules.v4'

To verify the IP tables rules, use the iptables command. Note that the output may show tcp or the number 6 and udp or the number 17:

nix
sudo iptables -L -v -n -t mangle

nix
sudo iptables -L -v -n -t mangle

output
text
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source               destination
1941  335K DIVERT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            socket
   0     0 DIVERT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            socket
...
Chain DIVERT (1 references)
pkts bytes target     prot opt in     out     source               destination
1941  335K MARK       all  --  *      *       0.0.0.0/0            0.0.0.0/0            MARK set 0x1
1941  335K ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0

output
text
Chain PREROUTING (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target     prot opt in     out     source               destination
1941  335K DIVERT     tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            socket
   0     0 DIVERT     udp  --  *      *       0.0.0.0/0            0.0.0.0/0            socket
...
Chain DIVERT (1 references)
pkts bytes target     prot opt in     out     source               destination
1941  335K MARK       all  --  *      *       0.0.0.0/0            0.0.0.0/0            MARK set 0x1
1941  335K ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0

To make the policy route (ip rule) and route table (ip route) changes persist after reboot, your next step depends on whether or not your system uses netplan. Typically, Ubuntu uses it, but Debian does not.

If your system uses netplan, persist the policy route (ip rule) and route table (ip route) changes in the netplan YAML configuration file located in /etc/netplan. The configuration file is probably the one having the lowest number and has a name like 00-installer-config.yaml or 01-netcfg.yaml.

Edit the netplan YAML file, adding an lo section under the ethernets level:

01-netcfg.yaml
yaml
network:
  ethernets:
    lo:
      routing-policy:
      - to: 0.0.0.0/0
        mark: 1
        table: 100
      routes:
      - to: 0.0.0.0/0
        type: local
        table: 100

01-netcfg.yaml
yaml
network:
  ethernets:
    lo:
      routing-policy:
      - to: 0.0.0.0/0
        mark: 1
        table: 100
      routes:
      - to: 0.0.0.0/0
        type: local
        table: 100

Then use sudo netplan try and sudo netplan apply before rebooting to make sure the configuration is valid. Ignore warnings about Open vSwitch.

If your system does not use netplan, persist the changes by creating a new service for loading them at boot. Create the systemd service file:

nix
sudo touch /etc/systemd/system/01-static-route.service
sudo vi /etc/systemd/system/01-static-route.service

nix
sudo touch /etc/systemd/system/01-static-route.service
sudo vi /etc/systemd/system/01-static-route.service

Add the following lines to the service file:

01-static-route.service
text
[Unit]
Description=Add route table 100
Wants=network-online.target
After=network-online.target
[Service]
Type=oneshot
# create the route table and rule
ExecStart=-/usr/sbin/ip route add local 0.0.0.0/0 dev lo table 100
ExecStart=-/usr/sbin/ip rule add fwmark 1 lookup 100
[Install]
WantedBy=multi-user.target

01-static-route.service
text
[Unit]
Description=Add route table 100
Wants=network-online.target
After=network-online.target
[Service]
Type=oneshot
# create the route table and rule
ExecStart=-/usr/sbin/ip route add local 0.0.0.0/0 dev lo table 100
ExecStart=-/usr/sbin/ip rule add fwmark 1 lookup 100
[Install]
WantedBy=multi-user.target

Set the service to start on boot:

nix
sudo systemctl enable 01-static-route.service

nix
sudo systemctl enable 01-static-route.service

Restart the system. The saved settings will be restored after the restart.

Create firewall rules:

nix
sudo firewall-cmd --permanent --direct --add-chain ipv4 mangle DIVERT
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle PREROUTING 0 -p tcp -m socket -j DIVERT
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle PREROUTING 0 -p udp -m socket -j DIVERT
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle DIVERT 0 -j MARK --set-mark 1
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle DIVERT 1 -j ACCEPT

nix
sudo firewall-cmd --permanent --direct --add-chain ipv4 mangle DIVERT
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle PREROUTING 0 -p tcp -m socket -j DIVERT
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle PREROUTING 0 -p udp -m socket -j DIVERT
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle DIVERT 0 -j MARK --set-mark 1
sudo firewall-cmd --permanent --direct --add-rule ipv4 mangle DIVERT 1 -j ACCEPT

Reload the firewall:

nix
sudo firewall-cmd --reload

nix
sudo firewall-cmd --reload

To persist the IP routing rules, create a new service for loading them at boot:

nix
sudo touch /etc/systemd/system/01-static-route.service
sudo vi /etc/systemd/system/01-static-route.service

nix
sudo touch /etc/systemd/system/01-static-route.service
sudo vi /etc/systemd/system/01-static-route.service

Add the following lines to the service file:

01-static-route.service
text
[Unit]
Description=Add route table 100
Wants=network-online.target
After=network-online.target
[Service]
Type=oneshot
# create the route table and rule
ExecStart=-/usr/sbin/ip route add local 0.0.0.0/0 dev lo table 100
ExecStart=-/usr/sbin/ip rule add fwmark 1 lookup 100
[Install]
WantedBy=multi-user.target

01-static-route.service
text
[Unit]
Description=Add route table 100
Wants=network-online.target
After=network-online.target
[Service]
Type=oneshot
# create the route table and rule
ExecStart=-/usr/sbin/ip route add local 0.0.0.0/0 dev lo table 100
ExecStart=-/usr/sbin/ip rule add fwmark 1 lookup 100
[Install]
WantedBy=multi-user.target

Set the service to start on boot:

nix
sudo systemctl enable 01-static-route.service

nix
sudo systemctl enable 01-static-route.service

Restart the system.

To verify the rule table, use the ip command:

nix
sudo ip rule ls

nix
sudo ip rule ls

output
text
...
32765:  from all fwmark 0x1 lookup 100
...

output
text
...
32765:  from all fwmark 0x1 lookup 100
...

To verify the route table, use the ip command:

nix
sudo ip route ls table 100

nix
sudo ip route ls table 100

output
text
local default dev lo scope host

output
text
local default dev lo scope host

At this point, you have completed the setup of the Route Health Injection module.

View the BIRD volatile table Jump to heading

To see the volatile table definition:

Edit the file /etc/hapee-extras/hapee-route.cfg.

Scroll down to the protocol volatile section.

hapee-route.cfg
text
protocol volatile vol1 {
  #  gateway <ip>
}

hapee-route.cfg
text
protocol volatile vol1 {
  #  gateway <ip>
}

By default, BIRD announces routes through the gateway configured on the network interface, but you can specify a different network gateway by uncommenting the gateway directive and typing its IP address.

For example:

hapee-route.cfg
text
protocol volatile vol1 {
  gateway 192.168.1.244
}

hapee-route.cfg
text
protocol volatile vol1 {
  gateway 192.168.1.244
}

You can add more volatile tables to support advertising routes for different frontends:

hapee-route.cfg
text
protocol volatile vol1 {
}
protocol volatile vol2 {
}

hapee-route.cfg
text
protocol volatile vol1 {
}
protocol volatile vol2 {
}

Then, prefix each route in the RHI module’s configuration, /etc/hapee-extras/hapee-rhi.cfg, with a table’s name:

hapee-rhi.cfg
text
vol1%192.168.1.10/32 = all(b:be_static,b:be_app)
vol2%192.168.1.11/32 = any(b:k8s_servers)

hapee-rhi.cfg
text
vol1%192.168.1.10/32 = all(b:be_static,b:be_app)
vol2%192.168.1.11/32 = any(b:k8s_servers)

Reference Jump to heading

This section describes the options available when configuring the RHI module.

RHI configuration file Jump to heading

This section describes the syntax of the RHI configuration file, /etc/hapee-extras/hapee-rhi.cfg.

text
<network>[,<network>,[...]] = <agg>(<b:|f:><name>[,<b:|f:><name>,[...]])

text
<network>[,<network>,[...]] = <agg>(<b:|f:><name>[,<b:|f:><name>,[...]])

Argument	Description
`<network>`	`[%<protoname>]{<ipv4>,<ipv6>}[/<mask>]` Specify an IPv4 or IPv6 CIDR subnet or list of several comma-delimited subnets. If you do not specify any subnet mask, RHI applies the /32 mask. For advanced configuration, you can supply the name of a volatile table in the `%<protoname>` section (default is `vol1`).
`<agg>`	Aggregation function: `all` - Returns true if all listed proxies are active. `any` - Returns true if at least one of the proxies listed is active. `never` - Always false. For debugging purposes.
`<b:\|f:>`	Prefix of either `b` for backend or `f` for frontend.
`<name>`	Name of the frontend or backend.

Product Documentation

API Documentation

Configuration Documentation

Route health injection

Concepts Jump to heading

How ECMP routing works Jump to heading

How Route Health Injection works Jump to heading

Prerequisities Jump to heading

Install and configure RHI Jump to heading

Install the RHI module Jump to heading

Configure route health injection Jump to heading

Intercept traffic destined for the IP Jump to heading

View the BIRD volatile table Jump to heading

Reference Jump to heading

RHI configuration file Jump to heading

See also Jump to heading

Product Documentation

API Documentation

Configuration Documentation

Concepts Jump to heading #

How ECMP routing works Jump to heading #

How Route Health Injection works Jump to heading #

Prerequisities Jump to heading #

Install and configure RHI Jump to heading #

Install the RHI module Jump to heading #

Configure route health injection Jump to heading #

Intercept traffic destined for the IP Jump to heading #

View the BIRD volatile table Jump to heading #

Reference Jump to heading #

RHI configuration file Jump to heading #

See also Jump to heading #

Privacy Settings

Concepts Jump to heading

How ECMP routing works Jump to heading

How Route Health Injection works Jump to heading

Prerequisities Jump to heading

Install and configure RHI Jump to heading

Install the RHI module Jump to heading

Configure route health injection Jump to heading

Intercept traffic destined for the IP Jump to heading

View the BIRD volatile table Jump to heading

Reference Jump to heading

RHI configuration file Jump to heading

See also Jump to heading