IP SLA's - how many?

[louis0001]

I'm thinking of configuring IP SLA's to monitor network quality for VoIP. We have 50 sites that come into our data centre via MPLS. This would obviously be where we put the receiver.

Questions are:

1. Would having 50 sites polling the one router have a detrimental effect on that router? eg processing, memory and traffic etc?

2. Would I be better putting the listener on the inside interface eg the LAN rather than the WAN interface?

Any pointers would be appreciated.

regards,

Louis

[Georg Pauwen · Accepted solution]

Hello,

you can check the IP SLA Q&A linked below (scroll down to about the middle and check Table 2).

It all depends on the kind of operation you are configuring. I don't think there is a hard limit on the numbers of SLAs. Some platforms and IOS versions also let you configure an 'ip sla low-memory' value to set how much unused memory must be available...

'https://www.cisco.com/en/US/technologies/tk648/tk362/tk920/technologies_qas0900aecd8017bd5a.html

[louis0001]

Good little bit of bedtime reading there. Everything I need. Thank you.

Expanding on from this, I've just done a quick test on an ADSL router we have (MPLS network 1) going to another router in MPLS 2 network. I'm not sure I trust the latency figures:

xxx_887#sh ip sla sta 17
IPSLAs Latest Operation Statistics

IPSLA operation id: 17
Type of operation: udp-jitter
Latest RTT: 1 milliseconds
Latest operation start time: 11:06:32 GMT Sun Nov 5 2017
Latest operation return code: OK
RTT Values:
Number Of RTT: 1000 RTT Min/Avg/Max: 1/1/28 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: 999
Number of DS Jitter Samples: 999
Source to Destination Jitter Min/Avg/Max: 0/1/28 milliseconds
Destination to Source Jitter Min/Avg/Max: 0/36/982 milliseconds
Packet Loss Values:
Loss Source to Destination: 0
Source to Destination Loss Periods Number: 0
Source to Destination Loss Period Length Min/Max: 0/0
Source to Destination Inter Loss Period Length Min/Max: 0/0
Loss Destination to Source: 0
Destination to Source Loss Periods Number: 0
Destination to Source Loss Period Length Min/Max: 0/0
Destination to Source Inter Loss Period Length Min/Max: 0/0
Out Of Sequence: 0 Tail Drop: 0
Packet Late Arrival: 0 Packet Skipped: 0
Voice Score Values:
Calculated Planning Impairment Factor (ICPIF): 11
MOS score: 4.06
Number of successes: 3
Number of failures: 0
Operation time to live: Forever

xxx_887#ping 10.1.28.24
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.28.24, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 24/27/28 ms
xxx_887#

The ping above is about right so I'm not sure what the ip sla is returning?

[Brian McPhillips]

Anyone know if there are updated details for the 4000 series for the maximum number of operations?

I can see in show ip sla application:

Estimated system max number of entries

and

Estimated number of configurable operations

Just wondering if there is anything official?