FireBrick FB6602, Руководство пользователя

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PPPoE
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For fibre to the cabinet (FTTC) and fibre to the premises (FTTP) service you connect the FB6000 directly to
the service with no extra equipment.
10.2. Definining PPPoE links
A PPPoE link is defined by a
ppp
top-level object. To create or edit PPPoE links in the web user interface,
select the "Interface" category icon - - under the section headed "PPPoE settings" you will see the list of existing
ppp
objects (if any), and an "Add" link.
For most situations, configuring a PPPoE link only requires that you specify the physical port number, or
alternatively, a port group name (see Section 6.2), that the router/modem is connected to and the login
credentials i.e. username and password. The port number or port group name is specified via the
port attribute
on the ppp object, and credentials are specified via the username and password attributes.
If you are connecting multiple routers/modems via a VLAN capable switch to a single FB6000 port, you will
also need to specify the VLAN used for the FB6000 to router/modem layer 2 connection - this is done by setting
the value of the
vlan
attribute too.
As an example, if you were to connect a single modem/router directly to port 4 on your FB6000 (i.e. not using
VLANs), then the configuration needed, shown as an XML fragment, would be :-
<ppp port="4" username="..." password="..."/>
You may also want to give the PPPoE link a name, by setting the
name
attribute - you can then reference the
link in, for example, a profile (see Section 8.2.2.1).
There are a number of additional options (see below), but for most configurations this is all you need. It causes
the FB6000 to connect and set a default route for internet access via the PPP link.
10.2.1. IPv6
If your ISP negotiates IPv6 on the link, then a default route is set for IPv6 traffic down the line. You just need
to configure your LAN subnet to have the IPv6 block your ISP has assigned to you.
10.2.2. Additional options
10.2.2.1. MTU and TCP fix
Normally PPPoE operates with a maximum packet size of 1492 bytes - this is due to the 8 byte PPPoE header
that is used, and the normal 1500 byte payload limit of an Ethernet packet. The FB6000 includes an option
to set the PPPoE MTU, so that when used with equipment capable of jumbo frames (such as BT FTTC and
FTTP services) this allows use of slightly larger frames to provide a 1500 byte MTU. To achieve this, simply
set the
mtu
attribute to a value of 1500. By default the
tcp-mss-fix
attribute is also set, which means when
working with a smaller MTU such as 1492, any connections that try and establish 1500 byte links are adjusted
on the fly to be the lower MTU. This avoids problems with a lot of corporate and bank web sites that do not
handle MTU and ICMP correctly. Typically your ISP will be doing this TCP fix for you as well.
Testing has been done which confirms setting mtu="1500" works correctly on BT FTTC lines.
Note
Testing using a Zyxel P660R in bridge mode confirms that BT 21CN ADSL lines will negotiate 1500
byte MTU, but it seems the Zyxel will not bridge more than 1496 bytes of PPP payload. If you select
more than 1492 MTU and have problems it could be that some device connecting you to the access