[Gllug] subnetting

[Paul Cupis]

On Thursday 11 November 2004 21:06, Ian Northeast 
<ian at house-from-hell.demon.co.uk> wrote:
> It appears that Cisco were a bit inconsistent
> when implementing that feature in IOS (but then Cisco are often
> inconsistent so no surprises there).

No, they implemented both the top and bottom subnets being unusable - 
from my quote: 

"Traditionally, it was strongly recommended that subnet zero and the
all-ones subnet not be used for addressing. According to RFC 950"

It's just that the command to enable both subnets is called "ip 
subnet-zero", which is a little misleading.

> Now that you mention it, Michael did mention an out of date Cisco
> router. I didn't take a lot of notice as it wasn't one I had heard
> of. I suppose I naively assumed that a Cisco router would work
> properly.

The IOS on the Cisco was probably implementing a current RFC at the time 
- it took them a little bit of time to implement the latter RFC (and 
you have to enable support for the newer RFC, which seems like an 
incorrect default - legacy compatibility probably).

Anyway, at least that seems to have cleared up the confusion from the 
OP. :)

Regards,

Paul Cupis
-- 
paul at cupis.co.uk

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