From: full-disclosure-bounces () lists grok org uk [mailto:full-disclosure-
bounces () lists grok org uk] On Behalf Of Giles Coochey
Sent: Wednesday, March 21, 2012 8:49 AM
To: full-disclosure () lists grok org uk
Subject: Re: [Full-disclosure] is my ISP lying or stupid?
On 2012-03-18 16:09, James Condron wrote:
The routers of an ISP are sorta DHCP in the sense that the IPs are
dynamic- DHCP really works as one network whereas an ISP switch will
have a series of /30 vlans for obvious reasons. Getting an IP and
connection is more complex than that but already we're down to a
series of routers.
No, they'd use private VLANs with the default router in a promiscuous sub-
VLAN. That way they won't have to waste 4 IPs for every customer.
Customers with multiple IPs can be put in community sub-VLANs, if they pay
Networking works very differently within Service Provider networks. A lot of it
is technology that makes itself look like other technologies you might be
familiar with, but what is happening behind the scenes is actually completely
Just thought you might like to know.
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