[c-nsp] Maximum switched ethernet daisy chain size

[Roy]

I suspect you are having some bandwidth issues.  Switches only have so 
much buffer space and momentary high usage can cause an overflow and 
packet loss

As an example I did a little googling.   I found a Cisco article on GE 
adapters for the 65xx series that shows the various queue sizes for 
different blades.

http://www.cisco.com/warp/public/cc/pd/si/casi/ca6000/prodlit/c60ge_ds.htm

Roy

Pavel Skovajsa wrote:
> Hello all,
> Recently I have found an interesting issue.
> I have found that on our network the packets that traverse more then
> 17 (18 and more) L2 ethernet switching hops all connected with MM
> fiber 1G links have lowered probability of arrival.
> The way I have found this is that our big ethernet ring with 30+
> switches was cut (fiber issue) behind 18th switch from L3 switch, and
> everybody hosted after 18th switch has some interesting packet loss
> issues.See the smokeping details for 18th switch on
> http://img171.imageshack.us/img171/3777/hop18kn4.jpg.
>
> This is not very logical for me, as switched ethernet works based on
> store&forward method so no old-school 5-4-3 rule applies as in shared
> collision (hub) environment. Anybody has a good explanation why adding
> more L2 hops to the path tends to kill packets?
>
> Regards,
> Pavel
>
> p.s. yes I know that building large ethernet rings is generally not a
> good idea, however sometimes due to large distances you have no other
> choice
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