# Health check did not work in GSLB **URL:** \ **Category:** ADC - Application Delivery\ **Tags:** gslb, health-monitor\ **Created:** [May 7, 2021, 7:26am UTC](https://community.a10networks.com/t/health-check-did-not-work-in-gslb/654 "2021-05-07T07:26:40Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![huzhiqi](https://avatars.discourse-cdn.com/v4/letter/h/ccd318/32.png) [@huzhiqi](https://community.a10networks.com/u/huzhiqi)\ **Post date:** [May 7, 2021, 7:26am UTC](https://community.a10networks.com/t/health-check-did-not-work-in-gslb/654/1 "2021-05-07T07:26:40Z")
I have three ISP line,ISP1,ISP2 and ISP3. We check the ISP’s health status with ICMP protocol,when ISP1 down,how to know the status?When ISP1 down,If the health check monitor go out through ISP2 or ISP3?So A10 can’t know the ISP1 down.The health check monitor did not work. ![WeChat Image_20210507152453.png](https://us1.discourse-cdn.com/flex002/uploads/a10_community/original/1X/601a60cede84f32058cc41eba434dc265552428c.png) ---
**Author:** ![jserrano](https://avatars.discourse-cdn.com/v4/letter/j/a9a28c/32.png) [@jserrano](https://community.a10networks.com/u/jserrano)\ **Post date:** [May 7, 2021, 8:06am UTC](https://community.a10networks.com/t/health-check-did-not-work-in-gslb/654/2 "2021-05-07T08:06:02Z")
Hi, Just use “gateway” option under site definition to enable Gateway Health Monitoring. Then you can create slb objects with each gateway´s internal IP and associate any HM containing the logic you desire to test its status When a gateway is declared down all the services hanging on this site are marked unusable (remember that a site represents a link when talking about Link Load Balancing). You can use this Link Load Balance config example as a reference: ##################### Diagram ![imagen.png](https://us1.discourse-cdn.com/flex002/uploads/a10_community/original/1X/6466a77de2ffe3dfcc0cff83a2715694f34c4c7c.png) _##################### notes - x.x.x.10 Are AX/TH physical ip´s on each segment_ _- 192.168.x.1 is the upstream gateway on each link_ _- 192.168.x.100 are used as hide nat for outbound traffic_ _- 192.168.x.100:25 are the smtp servers published on both links_ _- 192.168.x.100:80 are the web servers published on both links_ _- 192.168.x.100:53 is AX/TH DNS resolver on both links._  _- 192.168.x.100:XX is free to publish other services relying on different service groups._   ##################### Config interface ve 10  ip address 192.168.1.10 255.255.255.0 !  interface ve 20  ip address 192.168.2.10 255.255.255.0 !      interface ve 30  ip address 172.16.20.10 255.255.255.0  ip allow-promiscuous-vip !  ip route 0.0.0.0 /0 192.168.1.1 ip route 0.0.0.0 /0 192.168.2.1 100 ! ip route 0.0.0.0 /0 172.0.0.0/8 172.16.20.1 ! health monitor HM-Link  method icmp transparent 8.8.8.8 ! slb server GatewayLink1 192.168.1.1   health-check HM-Link   port 0 tcp     no health-check   port 0 udp     no health-check ! slb server GatewayLink2 192.168.2.1   health-check HM-Link   port 0 tcp     no health-check   port 0 udp     no health-check ! slb service-group GatewaysTCP tcp   method round-robin-strict   health-check HM-Link   member GatewayLink1:0   member GatewayLink2:0 ! slb service-group GatewaysUDP udp   method round-robin-strict   health-check HM-Link   member GatewayLink1:0   member GatewayLink2:0 ! ! **! OUTBOUND LLB** !  ip nat pool NATLink1 192.168.1.100 192.168.1.100 netmask /24  ip nat pool NATLink2 192.168.2.100 192.168.2.100 netmask /24  ip nat pool-group NATSalida NATLink1 NATLink2 ! !     access-list 100 permit ip 172.16.0.0 0.0.255.255 any  !  ! slb virtual-server OutboundLB 0.0.0.0 acl 100   port 0 tcp    name \_wildcard\_v4\_100\_TCP\_0    source-nat pool NATSalida    service-group GatewaysTCP    no-dest-nat   port 0 udp    name \_wildcard\_v4\_100\_UDP\_0    source-nat pool NATSalida    service-group GatewaysUDP    no-dest-nat   port 0 others    name \_wildcard\_v4\_100\_others\_0    source-nat pool NATSalida    service-group GatewaysTCP    no-dest-nat   ! ! ! **! INBOUND LLB** ! ! slb virtual-server “VS \_Inbound\_Link1” 192.168.1.100   port 25 tcp    name \_192.168.1.100\_TCP\_25      use-rcv-hop-for-resp    service-group G1:25   port 80 tcp    name \_192.168.1.100\_TCP\_80      use-rcv-hop-for-resp    service-group G1:80   port 53 dns-udp    name \_192.168.1.100\_DNS-UDP\_53      use-rcv-hop-for-resp    gslb-enable ! slb virtual-server “VS \_Inbound\_Link2” 192.168.2.100   port 25 tcp    name \_192.168.2.100\_TCP\_25      use-rcv-hop-for-resp    service-group G1:25   port 80 tcp    name \_192.168.2.100\_TCP\_80      use-rcv-hop-for-resp    service-group G1:80   port 53 dns-udp    name \_192.168.2.100\_DNS-UDP\_53      use-rcv-hop-for-resp    gslb-enable ! ! ! gslb service-ip ServiceIP\_Link1 192.168.1.100 ! gslb service-ip ServiceIP\_Link2 192.168.2.100 ! ! gslb site Link1   slb-dev local1 127.0.0.1    gateway 192.168.1.1    vip-server ServiceIP\_Link1 ! gslb site Link2   slb-dev local2 127.0.0.1    gateway 192.168.2.1    vip-server ServiceIP\_Link2 ! gslb policy LinkLB-General   dns active-only   dns selected-only 2   dns server authoritative    metric-order health-check weighted-ip weighted-site capacity active-servers active-rdt geographic connection-load num-session admin-preference bw-cost least-response admin-ip   no geographic ! ! gslb zone [a10net.com](http://inditex.com/)   policy LinkLB-General service http test1    dns-a-record ServiceIP\_Link1 ttl 5 static    dns-a-record ServiceIP\_Link2 ttl 5 static    admin-ip ServiceIP\_Link1 ServiceIP\_Link2   service smtp mail    dns-a-record ServiceIP\_Link1 ttl 5 static    dns-a-record ServiceIP\_Link2 ttl 5 static    admin-ip ServiceIP\_Link1 ServiceIP\_Link2 ! ##################### Regards ---
**Author:** ![huzhiqi](https://avatars.discourse-cdn.com/v4/letter/h/ccd318/32.png) [@huzhiqi](https://community.a10networks.com/u/huzhiqi)\ **Post date:** [May 7, 2021, 9:19am UTC](https://community.a10networks.com/t/health-check-did-not-work-in-gslb/654/3 "2021-05-07T09:19:20Z")
Not clear,“BALANCEADOR” means “A10”? Our A10 is deploy in Intranet with One-Arm mode,the A10 device is connected to a core switch like an extended arm. So,pls fix my issue.tks. ---
**Author:** ![jserrano](https://avatars.discourse-cdn.com/v4/letter/j/a9a28c/32.png) [@jserrano](https://community.a10networks.com/u/jserrano)\ **Post date:** [May 7, 2021, 9:48am UTC](https://community.a10networks.com/t/health-check-did-not-work-in-gslb/654/4 "2021-05-07T09:48:33Z")
Hi Huzhuqi, Sorry, “Balanceador” is A10 (Load Balancer in Spanish). The physical topology is not changing the idea under it: You need to create three servers pointing to the **internal interface** of each peering router. Then create a HM for them to determin its health, it can be a simple ping or something more complex (even an scripted monitor): health monitor HM-Link  method icmp ! slb server GatewayLink1 192.168.1.1    **health-check HM-Link**   port 0 tcp     no health-check   port 0 udp     no health-check ! slb server GatewayLink2 192.168.2.1    **health-check HM-Link**   port 0 tcp     no health-check   port 0 udp     no health-check ! Then when you create the GSLB Sites you need to configure a local device on each to stablish GSLB proto. There you can indicate the Gateway for each of them. When this Gateway is down the whole site (Link) is declared down with all its associated service IPs: ! gslb site Link1   slb-dev local1 127.0.0.1 ← use localhost or any floating IP     **gateway 192.168.1.1**    vip-server ServiceIP\_Link1 ! gslb site Link2   slb-dev local2 127.0.0.1 ← use localhost or any floating IP     **gateway 192.168.2.1**    vip-server ServiceIP\_Link2 !