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Seven Months with a VDSL2 Based Service
burakkucat:
It was last August, 2021, that I was migrated to a VDSL2 based service by my service provider, TalkTalk. Nothing special; no drama; no fuss.
As is probably well known by forum regulars, I had no great desire or need for such a service. Up until then, my experience of things VDSL2 was gained by setting up local circuits in "The Cattery", often with deliberate faults to see exactly how the service would be degraded.
Last month I decided to take a look at the real, live, service. As TalkTalk use IPoE for all residential services there is a field for a "DHCP Option 60 Vendor ID" string within the service configuration. I use a ZyXEL device as my CPE and, as I assume with all ZyXEL devices, the field is pre-populated with the string "dslforum.org". Having examined the D-Link device that TalkTalk had provided before the service was migrated and concluded that it was essentially junk, I was not going to use it. For fun, I decided to configure my ZyXEL device with "No_TalkTalk_Back_Door" as the DHCP Option 60 Vendor ID string.
The night before the experiment, I laid out the various items I was going to use and connected them all together. They were --
* An unlocked Huawei EchoLife HG612, with GUI, VLAN 301 deleted and QoS turned off.
* A Watchfront Firebrick, FB105, with port 1 mirrored to port 4. (The LAN1 port of the HG612 was connected to port 0 of the FB105. A computer, to perform a Wireshark capture, was connected to port 4 of the FB105.) Port 0 is on the untrusted side of the firewall, whilst ports 1 - 4 are on the trusted side of the firewall.
* My spare, backup, just-in-case, ZyXEL device was configured exactly as the normally used device with the exception that the xDSL interface was disabled and the EWAN interface was enabled. (Port 1 of the FB105 was connected to the EWAN port of the ZyXEL device.)
* A headless Raspberry Pi was connected to the LAN1 port of the ZyXEL device.On the day of the experiment, the xDSL port of the HG612 was connected to the centralised filter. Then --
* The FB105 was powered on.
* The computer was booted up and a Wireshark capture was started.
* The HG612 was powered on and allowed to synchronise with the cabinet based DSLAM.
* The ZyXEL device was powered on and the flurry of frames captured were closely watched in real-time. First the string "No_TalkTalk_Back_Door" was seen to be passed in the DHCP dialogue. :D (DHCP discovery sent via the WAN interface / DHCP offer received / DHCP accept sent to the gateway which provided the offer / DCHP acknowledgement received from the gateway, with all the usual gubbins.) Then the ZyXEL device synchronised its idea of the date and time with a host from the pool of UK time servers.
* The Raspberry Pi was powered on and, eventually, it too was seen to synchronise its idea of the date and time with a host from the pool of UK time servers.The Wireshark capture was then ended as, by this time, it had become very uninteresting. I then settled down with a laptop computer and performed my usual, daily, ritual. At the end of the day which, of course, included doing my normal tasks here everything was powered off and disconnected. The usual hardware configuration was then restored.
After considering the results obtained, above, I wondered what would be seen in a Wireshark capture if instead of the HG612 being the VLAN 101 endpoint, the ZyXEL was configured as that VLAN endpoint. A quick ASCII art diagram --
Centralised filter <--> HG612 <--> FB105 <--> ZyXEL device
VDSL2 ^ VLAN 101
& PTM | endpoint.
endpoints. | IPoE endpoint.
monitoring
computer
As can be seen above, I am considering monitoring "outside" of the VLAN. Does anyone have any idea what might be seen? (If anything.) Your opinions & comments will be appreciated, please. :)
[Edited to insert a [hr] separator.]
Weaver:
Excellent. What traffic do you expect to see? Anything odd?
Reformed:
--- Quote from: burakkucat on March 12, 2022, 07:08:50 PM ---Does anyone have any idea what might be seen? (If anything.) Your opinions & comments will be appreciated, please. :)
--- End quote ---
A DHCP discovery with some options set, a DHCP offer and a DHCP acknowledgement. After that Ethernet frames with a destination of the next layer 2 hop and IP of whatever your default gateway is on 101. Unless there's a TR-069 VLAN as well that'll probably be your lot. DSLAM strips any other VLAN tags, modem handles everything not Ethernet.
burakkucat:
--- Quote from: Weaver on March 13, 2022, 12:11:42 AM ---What traffic do you expect to see? Anything odd?
--- End quote ---
Last question first -- No, nothing odd whatsoever.
First question last -- Initially, the DHCP dialogue with the TalkTalk gateway, followed by my ZyXEL router setting its date & time (from a NTP server from the UK pool) and then all the normal traffic. Once I had seen the first two of those events, everything else was rather boring! There was the usual "ping - pong", "to and froing", between my ZyXEL router and a Juniper router in TalkTalk-land. (E.g. "Who's got X, tell Y". "Who's got Y, tell X". Almost ad infinitum but, logically, terminated when the session was terminated at the end of the day.)
burakkucat:
--- Quote from: Reformed on March 13, 2022, 01:07:56 PM ---A DHCP discovery with some options set, a DHCP offer and a DHCP acknowledgement. After that Ethernet frames with a destination of the next layer 2 hop and IP of whatever your default gateway is on 101. Unless there's a TR-069 VLAN as well that'll probably be your lot. DSLAM strips any other VLAN tags, modem handles everything not Ethernet.
--- End quote ---
Thank you.
As the novice that I am in such things ( :baby: ) I'll have to perform the experiment to gain some first hand experience. Once performed and the results analysed all should become clear.
[Edited to fix a grammatical mishap.]
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