Category:Incoming L2TP: Difference between revisions

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__NOTOC__<indicator name="L2TP">[[File:Menu-L2TP.svg|link=:Category:L2TP|30px|Back up to the L2TP Category]]</indicator>

= ~~L2TP~~ ~~from~~ ~~Customers~~ to ~~AAISP~~ =

= Why use out L2TP service? =

There are two reasons to use L2TP to connect in to AAISP:

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# Connect in to AAISP over a third-party internet connection.

#* This gives you your an AAISP IPv4 address and an IPv6 block. This will then give you unfiltered internet access with public IP addresses etc.

#* Speed is capped at 200Mb/s (3Mb/s for the low-cost Light service).

#* There are more reasons for doing this and further information and ordering on [https://www.aa.net.uk/broadband/l2tp-service/ A&A L2TP service].

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=== MTU ===

* see: [[L2TP MTU]]

The payload

{| class="wikitable"

|+ Rough guide for MTU for L2TP

|-

! ISP's Type !! ISP MTU !! L2TP MYU

|-

| Most broadband providers || 1492 || 1454

|-

| Broadband using Ethernet or baby jumbo frames RFC4638 || 1500 || 1462

|-

| Mobile or other || lower than 1492 || Lower than 1454

|}

* To find out the MTU of your underlying internet connection, see out [[MTU|MTU Page]]

* Generally, the L2TP MTU would be 38 bytes less than the MTU you have on the underlying internet connection.

* In theory fragments will work to allow 1500 MTU on our service, but fragments are inefficient, and if everyone sends fragmented packets that could degrade the service.

'''Technical Breakdown:'''

Here's a breakdown of the headers and the bytes used. This is using a standard PPP broadband connection where traffic through the ISP is 1492

Ethernet 1500 1500

802.11Q* - 4* 1500 (* Treated as part of the ethernet header and doesn't affect the MTU)

PPPoE - 6 1494

PPP - 2 1492 <-- the MTU of the underlying internet connection

IPv4 - 20 1472

UDP - 8 1464

L2TP - 6 1458

(HDLC) - 2 1456

PPP - 2 1454 <-- the MTU of the L2TP service

=== Port forwarding on some 'Mobile Broadband' routers ===

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= Notes on setting up L2TP IN to AAISP: =

{{AAMenu|img=menu-packet.svg|title=MTU|link=L2TP_MTU|text=Learn about MTU and L2TP}}

{{AAMenu|img=Menu-FireBrick.svg|link=L2TP_Client:_FireBrick|title=L2TP from FireBrick|text=Creating a L2TP connection from a FireBrick to AAISP}}

{{AAMenu|img=Menu-Apple.svg|link=L2TP_Client:_OSX|title=L2TP from OSX|text=Creating a L2TP connection from Apple OSX to AAISP}}