[afnog] Bridged Access Network

[Chris Wilson]

Hi all,

On Wed, 9 Oct 2013, Mark Tinka wrote:

>> We also putting a PPPoE concentrator for services which terminate 
>> directly onto the access switchports.
>
> I'd normally recommend DHCP (some industry folk call it IPoE) for 
> subscriber management in broadband scenarios, just because it's simple. 
> But some others still do PPPoE as well, and your access node would need 
> to understand a couple of DHCP Options anyway, the most common of which 
> is Option 82.

Beware PPPoE MTU issues. Maximum MTU for pppoe is 1492 bytes unless you 
can enable jumbo frames.

If you deploy anything with MTU < 1500, you will have weird issues outside 
your control (due to remote firewalls blocking ICMP TTL-exceeded messages, 
which is against the spec but they do it anyway) and that will give you 
support headaches, and you can only deploy additional hacks such as MSS 
clamping to work around them, which will give you more headaches, and you 
end up with one of these: https://en.wikipedia.org/wiki/Operation_Cat_Drop

Cheers, Chris.
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