What are metrics to measure the load in Cisco Routers

[khalilmeb]

I have a setup of Cisco CSR 1000v routers. I established a GRE tunnel between 2 routers, where the tunnel's source is the GigabitEthernet1 interface.

I aim to measure the load on that GRE tunnel. The load value can be calculated as the following:

Load (%) = Traffic (bps) / bandwidth or capacity (bps)

Where `Traffic(bps)` is the amount of traffic sent and `bandwidth or capacity (bps)` is the tunnel's capacity.

Literally, that information can be got from the router, but I got confused which one must be used in such calculation.

The `GRE tunnel` got the following configuration, and I know the amount of traffic I want to send which is `100Mbps`:

interface Tunnel0
bandwidth 256
ip address 10.10.1.1 255.255.255.252
load-interval 30
....
....
!

Is it correct to calculate the load as I showed above?

I found also the following information on the interface from the CLI`csr1000v#sh interfaces gigabitEthernet1`:

csr1000v#show interfaces gigabitEthernet 1
GigabitEthernet1 is up, line protocol is up 
...
reliability 255/255, txload 3/255, rxload 1/255
Encapsulation ARPA, loopback not set
Keepalive set (10 sec)
Full Duplex, 1000Mbps, link type is auto, media type is Virtual
output flow-control is unsupported, input flow-control is unsupported
...
Queueing strategy: fifo
Output queue: 0/40 (size/max)
30 second input rate 1000 bits/sec, 3 packets/sec
30 second output rate 4000 bits/sec, 1 packets/sec
1003836 packets input, 174201781 bytes, 0 no buffer
Received 0 broadcasts (0 IP multicasts)
...
169446 packets output, 80281698 bytes, 0 underruns
....

There is this txload and rxload values, would be used somehow to measure the loads?

[Giuseppe Larosa]

Hello Khalilmeb,

on the physical interface the txload/rxload refers to the speed of the interface

>>

Full Duplex, 1000Mbps, link type is auto, media type is Virtual

For the GRE tunnel that is a logical interface, setting a bandwdith of 256 kbps as you have done does not mean that traffic over the tunnel will be limited up to that bandwidth limit. Effective traffic can be more then configured bandwidth.

However, being a logical interface there is no concept of current actual speed of the interface so yes txload/rxload should refer to the stated bandwidth, but all traffic near to 256 kbps or greater will give you a 255/255 txload measure. As this is just a conversion of a percentage where 255/255 means 100%.

Edit:

Also notice that the calculation is actually an average made based on the 30 seconds load interval, it takes 4 time intervals for the average to reach the value of traffic with a constant speed.

With default 5 minutes load interval it takes 20 minutes for the average to reach the offered rate.

Hope to help

Giuseppe