upd: 7.2->8.1 & many networks trouble & flowtable

Andrey Groshev greenx at yartv.ru
Wed Nov 24 09:54:26 UTC 2010

Hi, PPL!

A couple of days ago decided to upgrade from 7.2-STABLE to 8.1-STABLE 
By tradition, waited some pitfalls.
But damn, not to the same degree!

The hardware on the server:
Motherboard: Intel SE7520JR23S
CPU's: 2 x Xeon 3Ghz
Ram: 4Gb

Software used: openospfd, openbgpd, bind, and so on.
In general, used as a boundary Router.

Update ... and began:
1. The server died a few minutes after launch, not even reacting to the 
keyboard. By issuing a warning about "em0 watchdog .....". I thought to 
myself - broke the driver, connect the other network card. Server even 
stopped hanging.
2. Nearest switch does not like OSPF from the server and it shuts down a 
port or vlan.
3. openbgpd loads CPU nearly 100%.
4. bind does not respond, despite the fact that properly loads the CPU.

In the end, I turned off everything that does not work as is necessary,
Only remaining process FLOWCLEANER which can be CPU at 100%.

Google started about this flowcleaner.
And what happened? I found a report entitled "Optimizing the BSD Routing 
System for Parallel Processing"(1). Roughly speaking, flowtable - a new 
approach to routing. Dividing the levels 2 and 3 can achieve more 
parallelism. But in the end, due to this - to increase network 
performance. Ok, everything looks great!

And now I ask: for whom all this? IMHO for example, ISP. Or, as stated 
in the above-mentioned report:

> >> "The main goals for redesigning the kernel routing infrastructure 
was to reduce the scope of the customization necessary when deriving 
products from FreeBSD, and to offer a generic solution that could be an 
integral part of the kernel." <<<

What ultimately relevant only to the equipment is used at the ISP.
Since the average user with its tiny routing table - it is not necessary.
But beyond the problems begin. How long have you seen the ISP without 
"fullview bpg"?

But beyond the problems begin.
Almost everywhere where it is mentioned a problem with FLOWCLEANER 
recommended for deletion from the kernel option FLOWTABLE.
And one of the co-authors wrote in his blog(2):
> >> "One oversight that come up shortly afterwards
is that it adversely impacts performance for systems
with many routing prefixes to a greater degree than I had expected." <<<

How long have you seen the ISP without "fullview bpg"?
It turns out that the technology is designed to increase network 
performance that most network generally kills, which implies that it is 
not suitable for use.
And here it is not simply included in the source tree, and is enabled by 
default in the GENERIC kernel!
And do not say that there was no PR - they are (3)!


Sorry so long sets out the main meaning of the message is this:
Why in the kernel introduced new features, if it is good only on paper?
May exclude this option from the GENERIC kernel?


1. - 
2. - http://daemonflux.blogspot.com/2010/01/updates.html
3. - 

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