Ping Q - Large Packet Sizes + Packet Loss

[andysaykao]

Just need some help understanding how ping works with large packet sizes and if this is a good test for packet loss?

Scenario:

- Customer has a 2M/640kb ADSL connection.

- They are reporting packet loss and speed issues claiming that large packet sizes should be going through (results below).

Customer pinging ISP's core-router:

cust-router#ping 210.x.x.1 size 4096 repeat 100

Type escape sequence to abort.

Sending 100, 4096-byte ICMP Echos to 210.x.x.1, timeout is 2 seconds:

!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!!!!!!!

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Success rate is 98 percent (98/100), round-trip min/avg/max = 100/103/108 ms

Now from the ISP's end.

ISP pinging customer's cpe:

core-router#ping 210.x.x.2 size 4096 repeat 100

Type escape sequence to abort.

Sending 100, 4096-byte ICMP Echos to 210.x.x.2, timeout is 2 seconds:

!!!!!!!!!!!!!!.!!!!!!!!.!!!!.!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!.!!!!.!!

!!!!!!!!!!!!!.!!!!!!!!!!!!!!!!

Success rate is 94 percent (94/100), round-trip min/avg/max = 108/125/324 ms

Is it normal behaviour that when I ping this 2M connection from our core router that I see packet loss and vice versa?

Also note that the Carrier has advised:

- Line test all good and Noise Margin with CT's modem @ 18dB.

- Noise Margin with customer's Cisco 2800 not so good @ 7.5dB.

Thanks in advance.

[spremkumar]

Hi

We did try this kinda excersises in other modes of connection (with various bandwidth capacities) and we tend to get packet loss when we exceed the bandwidth capacity of the pipe especially when we use larger packet size.

with the normal 64byte packet ping we dont get the drops but once you get onto higher values u choke up the bandwidth available sometimes and get these drops.

regds