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FTTC Modem: Difference between revisions
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[[Category:
=No longer supplied=
Note, these Openreach modems are no longer supplied.
With FTTC, BT
▲With FTTC, BT will supply and install a VDSL modem (the Active NTE in BT speak), You will then need a PPPoE device (router or software) to use the service.
*PPPoE Service Name = Blank
*PPPoE username = as supplied,
*PPPoE password = as supplied
*MTU = 1500 (if your equipment can handle baby jumbo frames and [http://www.faqs.org/rfcs/rfc4638.html RFC 4638]), otherwise 1492
*Auth Protocol = CHAP
= FTTC Modem =
If the sync light flashes, then there is no sync, and will probably need to be reported as a fault.▼
==Types==
The Openreach modem will either be:
*ECI Telecom - B-Focus
*Huawei EchoLife HG612
Openreach tend to install the FTTC modem to match the DSLAM in the Cabinet. However, later they were installing ECI modems whether the DSLAM is an ECI or not.
[[File:FTTCModems.png|600px]]
▲If the sync light flashes, then there is no sync, and will probably need to be reported as a fault.
How to tell the difference?
The 2 modems both look very similar! There are a few differences though:
*The ECI is larger
*The ECI has 'circular' LEDs, the Huawei has 'square' LEDs
*The ECI has a yellow LAN1 socket, The Huawei has a metallic LAN1 socket
[[File:FTTCModem-LEDs.png|600px]]
The FTTC modem supplied by Openreach is described in detail on [http://www.btplc.com/sinet/SINs/pdf/498v7p1.pdf BT SIN 498]
=Router Throughput=
|Linksys WRTU54G-TM
|24Mb
|style="color:red"|~
|Running OpenWRT trunk from [http://wiki.scottn.us here]. Disconnected PPP due to link saturation at default settings - adjust PPP options for stability
|-
|16Mb
|style="color:green"|16Mb
|It should be able to handle around
|}
=FireBrick 2700=
The Firebrick 2700 is a great router for FTTC, and even bonding FTTC. See the [[:Category:FireBrick|Firebrick]] pages for more info
=Testing and using FTTC with just a computer=
#Then will in the account name and password, click Connect (keep service name blank)
#You should be online, you may want to check firewall settings
=RFC 4638 Information=
When using a router with an external modem, one has to use PPPoE on the router as the connection method. This normally means that the MTU on the PPPoE link
Some pointers regarding RFC 4638, PPPoE and Linux-based routers.▼
can be no higher than 1492 octets (PPPoE has an 8 octet overhead, and the whole packets has to fit in a 1500 octet Ethernet frame). However, there is a
#The wan interface needs to be set to an MTU of 1508 on the assumption that there needs to be room for the 1500 mtu PPP package on the way to the modem (1500 may work - untested though).▼
technique to use ''baby jumbo frames'' to extend the Ethernet frame size to 1508 octets and allow the full 1500 octets on the PPPoE link.
In order to use baby jumbo frames on FTTC, the customer's router must support RFC 4638. It is not enough that the router supports baby jumbo frames via
configuration, the router must be able to do the negotiation described in RFC 4638.
▲#The wan interface needs to be set to an MTU of 1508 on the assumption that there needs to be room for the 1500
#You will require the unreleased ppp 2.4.6. In testing, ppp 2.4.5 with the rp-pppoe plugin updated to the latest version seems to work, although a recompile will be necessary. This can be fetched from ppp's website / git.
#Using ppp's debug option will allow you to see the rp-pppoe plugin negotiating a PPP-Max-Payload option
Ensure you're using [[Linux|kernel 2.6.34+ or 2.6.36.3+]]
=RFC 4638 on OpenWRT 10.03.1 (Backfire)=
Getting RFC4638 on Backfire is somewhat tricky, but do-able if you're feeling like fiddling with code!
In order to make it work:
#Look on your router and get hold of the complete ppp command line from the output of htop or /proc/(process id)/cmdline and save it somewhere.
#create an OpenWRT build environment for the 10.03.1 release so you can compile the new pppd release
#adapt the pppd 2.4.4 package definition to pull the 2.4.5 package from ftp.samba.org instead - you will need to update the version to 2.4.5 and the md5sum of the downloaded package.
#Pull the ppp 2.4.5 package patches from the (currently) "trunk" release and replace the 2.4.4 patches with these. The 2.4.4 patches are too outdated to apply to ppp 2.4.5.
#Use OpenWRT's patch making ability to create a patch that applies to 2.4.5 to update rp-pppoe to the latest release. The process is to create a new patch point in the build_root using quilt (see OpenWRT's wiki - surprisingly easy and well documented!), overwrite the 2.4.5 rp-pppoe plugin with the git version (ugly but it works...) and
#Re-compile the ppp package to create an installable .pkg. This is why you created a patch - the OpenWRT compile routine will wipe out any changes you make to the build_root.
#Use SCP to copy the new ppp and ppp-mod-pppoe packges to your router's /tmp
#Check your interfaces with ifconfig
#Check clueless to see if it sees your mru 1500
If you find after this that you can't start pppd (it doesn't show up in the ps list after you ifup wan, then run the command you saved at the start to run it and see if any errors are generated.
=RFC 4638 OpenWRT 12.09 (Attitude Adjustment)=
Patches for WNDR3x00 are available at https://github.com/mattwillsh/openwrt-wndr3x00-rfc4638
For machines that support baby jumbo MTUs of at least 1508, the ppp patch is all that's required.
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