NHLD health monitor config examples ?

Product Discussions ADC - Application Delivery
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1

Hi,

I have a scenario where a non-AS customer has contracted Internet connectivity with 3 ISPs and is doing NHLD.

What would be some commonly-used health monitors to determine which ISP link is up or down?
I’ve used DNS queries using Internet DNS servers with static routes to each DNS server going through a specific ISP, but that causes problems if one of the ISP CPEs is turned off or has the Ethernet cable disconnected - the static route vanished from the FIB and the destination is reachable through one of the other links, which causes the monitor to mark that gateway as up.

So, to solve that, I thought about combining two health monitors per ISP link, the one mentioned above + a ping to the CPE IP address - but again, this could be reachable through the Internet in case of a network disconnection between the CPE and the A10.

So I ask, what are some good practises and examples for health monitors in this kind of scenario?

BONUS if they are somehow connected to verifying the health of the links (jitter, packet discards, latency, and the such, maybe something similar to RTT…).

Thank you!
Rodolfo

2

Here’s the relevant configuration (non-relevant sections removed)
PART 1

interface ethernet 1
 name LOCAL_AREA_NETWORK
 enable
 ip address 192.168.31.1 255.255.255.0
 ip allow-promiscuous-vip
!
interface ethernet 2
 name TELEFONICA_VIVO_FIBRA
 enable
 ip address 192.168.15.254 255.255.255.0
!
interface ethernet 3
 name CLARO_NET_VIRTUA
 enable
 ip address dhcp
!
ip route 208.67.220.220 /32 192.168.0.1
!
ip route 208.67.222.222 /32 192.168.15.1
!
health monitor MONITOR_DNS_VIVO
  override-ipv4 208.67.222.222
  override-port 53
  interval 3 timeout 3
  method dns domain google.com port 53 expect response-code 0 recurse enabled type A
!
health monitor MONITOR_DNS_CLARO
  override-ipv4 208.67.220.220
  override-port 53
  interval 3 timeout 3
  method dns domain google.com port 53 expect response-code 0 recurse enabled type A
!
health monitor MONITOR_PING_VIVO
  override-ipv4 192.168.15.1
  interval 3 timeout 3
!
health monitor MONITOR_PING_CLARO
  override-ipv4 192.168.0.1
  interval 3 timeout 3
!
3

PART 2

slb server ISP_CLARO 192.168.0.1
  health-check MONITOR_PING_CLARO
  port 0 tcp
    health-check-disable
  port 0 udp
    health-check-disable
!
slb server ISP_VIVO 192.168.15.1
  health-check MONITOR_PING_VIVO
  port 0 tcp
    health-check-disable
  port 0 udp
    health-check-disable
!
slb service-group SVCGRP_TCP tcp
  member ISP_CLARO 0
  member ISP_VIVO 0
!
slb service-group SVCGRP_UDP udp
  member ISP_CLARO 0
  member ISP_VIVO 0
!
slb template persist source-ip PERSIST_SRCIP
  incl-dst-ip
  match-type server
!
slb template persist ssl-sid PERSIST_SSL
!
slb virtual-server ISP_LB 0.0.0.0 /0
  port 0 others
    name LB_OTHERS
    clientip-sticky-nat
    access-list 1
    source-nat auto
    service-group SVCGRP_TCP
    use-rcv-hop-for-resp
    template persist source-ip PERSIST_SRCIP
    no-dest-nat
  port 0 tcp
    name LB_TCP
    clientip-sticky-nat
    access-list 1
    source-nat auto
    service-group SVCGRP_TCP
    use-rcv-hop-for-resp
    template persist source-ip PERSIST_SRCIP
    no-dest-nat
  port 0 udp
    name LB_UDP
    clientip-sticky-nat
    access-list 1
    source-nat auto
    service-group SVCGRP_UDP
    use-rcv-hop-for-resp
    template persist source-ip PERSIST_SRCIP
    no-dest-nat