topic ft track host priority in Application Networking

ft track host priority

12pratham — Tue, 08 May 2012 21:38:03 GMT

Need some help in understanding the priority value , below is my ft track host conifg and the output

ft interface vlan 1003
ip address 1.1.1.1 255.255.255.252
peer ip address 1.1.1.2 255.255.255.252
no shutdown

ft peer 1
heartbeat interval 300
heartbeat count 10
ft-interface vlan 1003
ft group 10
peer 1
priority 255
peer priority 250
associate-context Admin
inservice

ft track host GATEWAY
track-host 10.1.3.2
peer track-host 10.1.3.3
probe PROBE_ICMP priority 100
peer probe PROBE_ICMP priority 50

/Admin# sh ft track summary

FT Group                     : 10
Status                       : in-service
Maintenance mode             : MAINT_MODE_OFF
My State                     : FSM_FT_STATE_ACTIVE
My Config Priority           : 255
My Net Priority              : 255
My Preempt                   : Enabled
Context Name                 : Admin
Context Id                   : 0
Track Name                   : GATEWAY
Track type                 : TRACK_HOST
Host IP Address            : 10.1.3.2
State                      : TRACK_UP
Priority                   : 0 ( why its shows the priority as 0 )
Probe name                 : PROBE_ICMP
    State                    : TRACK_UP
    Priority                 : 100

Have the priority for my ft group is 255 , and for ft track host is 100 (255-100) 155

and for the standy ft group is 250 and ft track host is 50 (250-50) 200

If the track host is not reachable then will it failover successfully as i have the higher priority value for ACE2 which is 200

ft track host priority

gaursin2 — Wed, 09 May 2012 01:30:23 GMT

Hello,

your first doubt is why priority is "0" in the output. We have two options when we create a track hot for a FT group, either assign priority to probe (which you have done) or we define priority to track host (not to probe) which will reduce the priority of the FT group in case all the associated probes attach to that track host has failed.

Configuring priority is useful in scenarioes where in we have multiple track hosts and we want to give priorities to various hosts. default is 0

Coming to you second q? in case both FT peer loss their track hosts there will be a failover (as per new priorities)

ft track host priority

12pratham — Wed, 09 May 2012 02:07:17 GMT

Gaurav thanks for your response

So inthat case my config should work ,there should not be any issues.Please let me know if I need add or delete any of the priority

ft track host priority

gaursin2 — Wed, 09 May 2012 02:46:10 GMT

see as far as FT fail over is concern this will work. But i am not very clear with your objective of FT tracking host. My doubt is why u r tracking different IP for both FT peer (10.1.3.2 for this peer and 10.1.3.3 for remote peer). what i understand the objective of tracking was to track a single device (like gateway) from both peers and change priorities for FT failover, so that device with no gateway reachable shound go standby.

in your case even when both peers have lost their track hosts still there will be a failover, not clear what failover will acheive.

but if its your requirement and this is what you want to achieve your configuration is good.

ft track host priority

gaursin2 — Wed, 09 May 2012 03:13:57 GMT

Still not clear with topolgy

10.1.3.2 and 10.1.3.3 are switches connected to ACE device respectively (ACE-1 connected to 10.1.3.2 and ACE 2 connected to 10.1.3.3). And then you are tracking 10.1.3.2 on ACE-1 and 10.1.3.3 on ACE-2. When 10.1.3.2 is unreachable ACE-1 priority reduce to 155 (255-100), so ACE-2 will take over. Now suppose ACE-2 also loss 10.1.3.3 then it will reduce its priority 200 (250.50), so its still higher it will remain Active.

now my q? what is 10.1.3.2 and 10.1.3.3 any ways related to ACE routing part (not physical connectivity). Are they gateway for routes or what. Or reframing the q? what will happen on ACE-1 traffic forwarding mechanism if 10.1.3.2 is lost (forget FT for time being). Will this make ACE-1 unreachable to rest of network? Similar for ACE-2 and 10.1.3.3

I hope u got what i want to know..

Re: ft track host priority

12pratham — Wed, 09 May 2012 03:22:12 GMT

Gaurav thanks for explaining me in detail ,I guess the better choice would be to track interface vlan ,which ever is configured on ACE ,that way I will be tracking same vlan

ft track interface Admin

track-interface vlan 5

peer track interface vlan 5

priority 100

peer priority 50

This should solve my scenario I guess ,If ace 1 loses track of vlan 5 ,ACE2 should become primary,and when ACE1 vlan will be available it should become active as I have the preempt enabled .

Please let me know if it makes sense

ft track host priority

gaursin2 — Wed, 09 May 2012 03:44:48 GMT

i will again say yes it is also good for your setup of failover requirementand yes with your configuration your failover will work as expected.