NETWORK LATENCY 3

[tmandu]

I am going to move to a 768K 12 channel T1 for our connection to the internet. MY telcom is asking me to write the specs for network latency.

DO you think that 75 milliseconds is standard for the round trip transmission delay. Is this to much or to little ?
In other words I would ask for something like this;

XYZ guarantees that the maximum network latency, calculated as the average round trip transmission delay on the XYZ network, is 75 milliseconds or less. If XYZ does not meet these specs --- then they will credit us 10% of monthly charge.

How would I check this ??

Also do you think packet loss of 1% is also not asking for too much.

Can you think of anything else that I should ask for in writing before we sign with them ?? I am asking for 99.9 % availability with notification for equipment changes etc...


Thanks.

 

[gunthnp]

75m to where there router that about right, but to website can be a few hundered and to user like them visting a web page you have can be even longer it. 99.9 up time for an isp is about standard most netwroks if you messure over a period of time have a bout 5% loss any thing more then that is a problem. So long and thanks for all the fish.

 

[sehiser]

I am partnered with an ISP here locally. We have 3 T-1's and an OC-3 coming in crossing from TCP/IP on 2000 over to Novell on IPX/SPX for security. Running all mid-range lucent routers and switches with less than a 1% loss on average, max of 3%. 75ms sounds fair.

I would say 3% average loss, max of 5%. That's being very liberal too. It depends on how large of a company they are and your area, if you can get them to agree on 1% then you have better access to a 10% discount.

I would also find out more about their backbone. I've seen great deals on T-1 or better access but it gets bottled necked on the backbone. One location I was at diced up 10 locations on a T-1 for their intranet access and X Windows. The backbone killed the connection occasionally, sometimes dial-up seemed like paradise. The only thing they can promise is their equipment and local to tap xfer rates and times. I would do some background research into everything beyond that. Around here it's a 3 years lease for a T-1, so it would be in the best interest to research into it.

Scott

 

[wybnormal]

Be careful here.. any protocol like SNA, even if it's run over DLSW, will not tolerate the loss of ANY packets. I run 2 links from LA to NJ without ANY loss over a 24 hour period. I know.. I keep the logs on it The rule of thumb if you want to call it that is 5 mS delay per hop plus the distance induced delay.. so my local links run 10-20mS and my longest link at 3,000 miles of distance runs 70 to 80mS. Anything over 90mS is considered trouble and over 120 it's considered broken and a trouble ticket is called in.

One thing else to remember is that PING which is based on ICMP will be one of the last packets answered when the router is under load, or dropped completely..even if data packets are making it through. A better utility is TRACEROUTE which uses UDP on the send side and ICMP on the response side.

Just some thoughts.

Mike S
"Diplomacy; the art of saying 'nice doggie' till you can find a rock" Wynn Catlin