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less than 64 bits TCP length

wong seng guan
Frequent Advisor

less than 64 bits TCP length

Hi,

I have 2 DS10 Alphaserver with version 7.3.1 OpenVMS with TCPware 5.6.2. one for online and one for backup purpose.

Im using network analyzer to capture the network activity between DS10 and OSS server.

The online DS10 unit is running fine communicating with OSS server but i found out the spare DS10 look like seldom communicate with the OSS server even it is spare unit.

Tha data capturing by network analizer was displayed the message TCP length has less then standared TCP lenght 64 bits and it cause the spare DS10 re-sent the packets and re-acknowlegde by the server all the way.

Spare DS10 was running fine when i activated it to online but same message again for whatever DS10 unit become a spare.

1) Is that any communications or setting problem between OSS server and DS10?

2) why the TCP length has less than standard 64bits? and cause the both server keep on re-sent and re-acknowledge the packets

Thanks

Jason



5 REPLIES
Wim Van den Wyngaert
Honored Contributor

Re: less than 64 bits TCP length

Jason,

"In both standards Ethernet II and IEEE 802.3, frames have a minimal size of 64 bits
and a maximal size of 1518 bits. The structures of those two types of frames are
different."

Any errors in mc lancp show dev/count ?

Wim
Wim
John Gillings
Honored Contributor

Re: less than 64 bits TCP length

Jason,
Make sure the adapter is set to "AUTO" at the console level. Your symptoms could be due to a duplex mismatch.

The adapter setting MUST match that of the port on the switch or hub. Most switches these days are auto-negotiate, so that's what you should set your Alphas to.

A crucible of informative mistakes
wong seng guan
Frequent Advisor

Re: less than 64 bits TCP length

Hi,

There are ZERO frame check error, ZERO frame size error, ZERO frame length error when i was issued command mc lancp dev/count.

The adapters in CP already had set to half duplex with speed 100Mbps because of connected to hub and run with TCPWare 5.6-2.

is there any possibility problem?
Cass Witkowski
Trusted Contributor

Re: less than 64 bits TCP length

The minimum packet is 64 bytes not 64 bits
wong seng guan
Frequent Advisor

Re: less than 64 bits TCP length

Hi,

Cass, You are right. i should correct it. There should be less then 64 bytes in frames length in mt questions.

Do you have any idea about my questions?

Thanks