Setting IP SLA to detect breaks on a link and failover.

ghostface · ‎08-20-2018

I have a network that uses 3 ISP connections and I noticed that the primary link mostly breaks very badly. but the IP SLA only notices when the link is totally down. So in this case the failover does not happen because it still receives reach-ability and even when the other secondary links should be better those links still don't get injected into the routing table as primary.

I need to be able to set an IP SLA that will check based and the reliability and then switch the secondary to primary in the routing table.

Routing on Multiple Links

Eg. If the IP SLA uses ICMP and gets Reply with 5/10 it should try to switch to the next route available.

Thanks

Georg Pauwen · ‎08-20-2018

Hello,

instead of icmp echo, you could configure icmp jitter, which lets you define the link quality on a more granular level. Below is an example. That said, do you get any syslog entries when you the line 'breaks' ? Because you could also do the failover based on syslog entries...

ip sla 1
icmp-jitter 192.168.1.2 interval 4 num-packets 10 source-ip 192.168.1.2
frequency 5
!
ip sla reaction-configuration 1 react jitterAvg threshold-value 5 2 action-type trap
threshold-type immediate
!
ip sla schedule 1 start-time now life forever

ghostface · ‎08-20-2018

Dear Georg.

I have been looking at this also but i'm a bit new to this kind of SLA.

I understand a bit of these commands but I'd like to know how I'll be able to do it on a router with 3 ISP Links to failover between them based on the quality.

Also is you could show me how to get it done with the syslog messages because i can setup a syslog server right away.

Regards

ghostface · ‎08-20-2018

Dear George.

I have been looking at this also but i'm a bit new to this kind of SLA.

I understand a bit of these commands but I'd like to know how I'll be able to do it on a router with 3 ISP Links to failover between them based on the quality.

Also is you could show me how to get it done with the syslog messages because i can setup a syslog server right away.

Regards

Georg Pauwen · ‎08-20-2018

Hello,

best to post your full running configuration, so we can fill in the necessary bits and pieces. Also, what syslog messages are being logged when the line breaks ?

ghostface · ‎08-30-2018

I have done the setup and the SLA is not working. pls view config.

!
track 1 ip sla 1
!
!
interface GigabitEthernet0/1
description Last-Resort
ip address 1.1.85.193 255.255.255.252
duplex auto
speed auto
media-type rj45
!
!
interface FastEthernet0/0/2
description Pri
switchport access vlan 17
switchport trunk native vlan 2
no ip address
no cdp enable
spanning-tree portfast
!
interface FastEthernet0/0/3
description Sec
switchport access vlan 19
no ip address
no cdp enable
spanning-tree portfast
!
interface Vlan1
description Customer
ip address 1.1.85.177 255.255.255.248
!
interface Vlan17
description PRI
ip address 1.1.85.197 255.255.255.252
!
interface Vlan19
description Sec
ip address 1.1.85.165 255.255.255.252
!
!
!
ip route 0.0.0.0 0.0.0.0 1.1.85.198 name Trango track 1
ip route 0.0.0.0 0.0.0.0 1.1.85.166 10
ip route 0.0.0.0 0.0.0.0 1.1.85.194 20
!
ip sla 1
icmp-jitter 8.8.8.8 source-ip 1.1.85.177 interval 4
frequency 5
ip sla schedule 1 life forever start-time now
ip sla reaction-configuration 1 react jitterSDAvg threshold-value 5 2 threshold-type immediate action-type trapAndTrigger

#sh ip sla statistics
IPSLAs Latest Operation Statistics

IPSLA operation id: 1
Type of operation: icmp-jitter
Latest RTT: NoConnection/Busy/Timeout
Latest operation start time: 16:05:23 UTC Thu Aug 30 2018
Latest operation return code: Timeout
RTT Values:
Number Of RTT: 0 RTT Min/Avg/Max: 0/0/0 milliseconds
Latency one-way time:
Number of Latency one-way Samples: 0
Source to Destination Latency one way Min/Avg/Max: 0/0/0 milliseconds
Destination to Source Latency one way Min/Avg/Max: 0/0/0 milliseconds
Jitter Time:
Number of SD Jitter Samples: 0
Number of DS Jitter Samples: 0
Source to Destination Jitter Min/Avg/Max: 0/0/0 milliseconds
Destination to Source Jitter Min/Avg/Max: 0/0/0 milliseconds
Packet Late Arrival: 0
Out Of Sequence: 0
Source to Destination: 0 Destination to Source 0
In both Directions: 0
Packet Skipped: 0 Packet Unprocessed: 0
Packet Loss: 0
Loss Periods Number: 0
Loss Period Length Min/Max: 0/0
Inter Loss Period Length Min/Max: 0/0
Number of successes: 0
Number of failures: 66
Operation time to live: Forever

#sh ip sla configuration 1
IP SLAs Infrastructure Engine-III
Entry number: 1
Owner:
Tag:
Operation timeout (milliseconds): 5000
Type of operation to perform: icmp-jitter
Target address/Source address: 8.8.8.8/41.78.85.177
Packet Interval (milliseconds)/Number of packets: 4/10
Type Of Service parameter: 0x0
Vrf Name:
Schedule:
Operation frequency (seconds): 5 (not considered if randomly scheduled)
Next Scheduled Start Time: Start Time already passed
Group Scheduled : FALSE
Randomly Scheduled : FALSE
Life (seconds): Forever
Entry Ageout (seconds): never
Recurring (Starting Everyday): FALSE
Status of entry (SNMP RowStatus): Active
Threshold (milliseconds): 5000
Distribution Statistics:
Number of statistic hours kept: 2
Number of statistic distribution buckets kept: 1
Statistic distribution interval (milliseconds): 20
Enhanced History:

#sh ip sla reaction-configuration 1
Entry number: 1
Index: 1
Reaction: jitterSDAvg
Threshold Type: Immediate
Rising (milliseconds): 5
Falling (milliseconds): 2
Action Type: Trap and trigger

ghostface · ‎08-30-2018

i have been able to get it to work now by changing the destination IP for the sla. but i need to know if the config is correct in regards to the following.

1. after 10 pings with 5 timeouts it should take the primary down and fall to the next.

2. how do i do the sla for the second route so that if the first and second are breaking badly it should take the last.

Regards