multiple routing tables review patch ready for simple testing.

Bruce M. Simpson bms at FreeBSD.org
Tue Apr 29 20:25:57 UTC 2008


Julian Elischer wrote:
>>
>> A general purpose OS is a different beast as it has no physical
>> equivalent of the FIB. It may have multiple routing tables, though, to
>> I think setrib would be a term less likely to cause confusion then
>> setfib even though, in the case of your FreeBSD patches, it's really
>> both.
> If we need to change the terminology now is the time..
> I asked for comments on terminology before and this is what we
> came up with.. but once it gets committed.... it gets set in stone.

The kernel forwarding table is not a RIB.

In the past some apps have tried to use it as one. They really shouldn't 
do that.

There are implementation constraints on the inter-process communication 
involved (PRC_ATOMIC, etc) which make it inherently unsuitable as a 
place for routing daemons to exchange routes, particularly when the 
system is under load, or running near load limits, as would be the case 
with a tightly engineered embedded system.

I understand folk went down that road in the past, as a means to get 
something up and running quickly as a working demo, or as a hangover 
from the days when they were the only tools around, but it isn't the way 
to build a comms infrastructure.

These days general purpose OSes are getting closer to specialised comms 
equipment in terms of what they can do, but more importantly, so are 
people's expectations of them -- and thus people's concern about whether 
or not it works tends to follow.

cheers
BMS


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