[c-nsp] IP SLA RTT question...

[Mark Tohill]

Hi, 

I don't remember seeing IP SLA-related questions on the list before so I
hope this is not off-topic.
I setup the following: 

R1----R2----R3 

R1 configured as IP SLA source/responder to R3. 
R3 configured as IP SLA source/responder to R1. 
R2 configured just to route traffic. 

R1 configured with the following: 

ip sla monitor 1 
type udpEcho dest-ipaddr 192.168.20.1 dest-port 5000 
request-data-size 160 
ip sla monitor schedule 1 life forever start-time now 
ip sla monitor 2 
type jitter dest-ipaddr 192.168.20.1 dest-port 5000 num-packets 20
interval 10 
request-data-size 160 
ip sla monitor schedule 2 life forever start-time now 

R3 configured pretty much the same, only in reverse direction: 

ip sla monitor responder 
ip sla monitor 1 
type udpEcho dest-ipaddr 192.168.10.1 dest-port 5000 
request-data-size 160 
ip sla monitor schedule 1 life forever start-time now 
ip sla monitor 2 
type jitter dest-ipaddr 192.168.10.1 dest-port 5000 num-packets 20
interval 10 
request-data-size 160 
ip sla monitor schedule 2 life forever start-time now 

Looking at results on R1 for UDPEcho(1) and UDPJitter(2) operations: 

R1#sh ip sla monitor statistics 1 
Round trip time (RTT) Index 1 
Latest RTT: 166 ms 

R1#sh ip sla monitor statistics 2 
Round trip time (RTT) Index 2 
Latest RTT: 864 ms 

The RTT values for UDPEcho and UDPJitter dont change significantly over
time. 
Also, random extended pings show values closer to the echo operation
i.e. approx 160ms  average RTT, even though it's ICMP.

Is there a reason why there is such a difference in the udpecho and
udpjitter values? 

Thanks,Mark 


Mark Tohill
UTV Internet
T:+44 (0)28 90 262196
M:+44 (0)7786 278716
E:mark at u.tv <BLOCKED::mailto:mark at u.tv>