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Groups > comp.os.linux.misc > #89336
| From | "Carlos E. R." <robin_listas@es.invalid> |
|---|---|
| Newsgroups | comp.os.linux.misc |
| Subject | Re: Multi-Networking in Linux - Multiple Subnets - Movistar "docs" |
| Date | 2026-07-31 14:25 +0200 |
| Message-ID | <nd3ihnFi6v5U6@mid.individual.net> (permalink) |
| References | (1 earlier) <nd0nqeF52jrU2@mid.individual.net> <114fdad$1trk7$1@news1.tnib.de> <nd0sj4F52jqU1@mid.individual.net> <114fuuv$1v1g1$1@news1.tnib.de> <nd3fptFi6v5U4@mid.individual.net> |
On 2026-07-31 13:38, Carlos E. R. wrote:
> On 2026-07-30 18:43, Marc Haber wrote:
>> "Carlos E. R." <robin_listas@es.invalid> wrote:
>>> On 2026-07-30 13:42, Marc Haber wrote:
>>>> "Carlos E. R." <robin_listas@es.invalid> wrote:
>> Please, let me see that ISPs customer documentation. They do have it
>> online, don't they? I'm familiar with that industry for nearly 30
>> years and have never seen a setup like that. It sounds so brain-dead
>> that my first idea was that you haven't understood.
>
> There is no documentation. They keep it secret. What is known is by
> reverse engineering.
I can, however, ask ChatGPT to explain the configuration of the Telefónica fibre router. I once did.
Ah, yes—that's a much more interesting question. You're asking about **Movistar's actual network architecture as delivered to the customer**, not the router UI. Fortunately, this is reasonably well understood because many people have reverse-engineered it.
The fibre entering your house is not just "Internet." It's an Ethernet trunk carrying several services over IEEE 802.1Q VLANs.
A typical FTTH connection looks conceptually like this:
```
Fibre (GPON/XGS-PON)
OLT
│
─────────────────
│
Optical fibre
│
HGU / ONT
│
┌────────────┼────────────┐
│ │ │
Internet IPTV VoIP
```
The ONT converts GPON into Ethernet frames while preserving VLAN tags.
## VLAN layout
Historically (and still on many installations) Movistar uses:
| VLAN | Service |
| ---: | --------------------- |
| 6 | Internet |
| 2 | IPTV (Movistar Plus+) |
| 3 | VoIP |
These numbers have been remarkably stable for years.
The HGU internally creates three virtual interfaces:
```
eth0.2
eth0.3
eth0.6
```
where:
* `.2` is TV
* `.3` is telephone
* `.6` is Internet
The customer never sees these because they're terminated inside the router.
---
## Internet (VLAN 6)
This is the normal routed connection.
Historically it used PPPoE.
Nowadays most residential connections use **IPoE (DHCP)**.
The router obtains:
* one public IPv4 address
* gateway
* DNS
Then NAT is performed towards:
```
192.168.1.0/24
```
---
## IPTV (VLAN 2)
This is completely separate from Internet.
The TV decoder doesn't simply stream Netflix-like traffic over the Internet.
Instead it joins multicast groups using:
* IGMP
* IGMP Proxy
* IGMP Snooping
The flow is roughly:
```
TV Decoder
↓
IGMP Join
↓
Router
↓
VLAN 2
↓
Movistar TV network
```
Once subscribed, multicast packets are forwarded only to ports that requested them.
That's why the router has several hidden multicast-related options.
This separation also allows TV traffic to receive different QoS treatment from Internet traffic.
---
## Voice (VLAN 3)
The analogue phone ports on the HGU are actually connected to a SIP client running inside the router.
Internally:
```
Phone
↓
ATA
↓
SIP
↓
VLAN 3
↓
Movistar VoIP servers
```
The customer normally never sees:
* SIP username
* SIP password
* registrar
* codecs
These are provisioned automatically through Movistar's management system.
---
## Management
There is effectively another "service" that's not customer-facing.
The router maintains a management connection using protocols such as:
* TR-069 (CWMP)
* ACS (Auto Configuration Server)
This allows Movistar to:
* change Wi-Fi settings remotely (through the Smart WiFi app)
* update firmware
* reset configuration
* collect diagnostics
* reprovision services
So even if you never touch the router, it is periodically contacting Movistar's management servers.
---
## QoS
Because Internet, TV, and VoIP are already separated at Layer 2 using VLANs, the router can prioritize traffic approximately like this:
```
Highest priority
Voice
Medium
IPTV
Lower
Internet
```
This ensures that a large download doesn't interfere with phone calls or TV.
---
## If you replace the router
This is where things become interesting.
If you connect your own router directly to the ONT (or use an SFP GPON/XGS-PON module), you need to recreate those VLAN interfaces yourself:
```
WAN
├── VLAN 6 → Internet
├── VLAN 2 → IPTV
└── VLAN 3 → VoIP
```
Many users only configure VLAN 6 because they don't use the landline or Movistar TV. In that case, everything works except those services.
If you want the TV decoder to function correctly, you also need IGMP proxying and multicast support on VLAN 2. If you want the telephone service, you either need the SIP credentials (which Movistar does not normally provide) or you keep the HGU solely for VoIP.
---
So the "result" of Movistar's setup is essentially that your fibre presents **three logically independent Ethernet networks** over a single optical connection. The HGU acts as a demultiplexer:
* **VLAN 6 → Routed Internet (NAT to 192.168.1.0/24)**
* **VLAN 2 → Multicast IPTV network**
* **VLAN 3 → SIP/VoIP network**
From the customer's perspective it looks like one broadband connection, but at the Ethernet level it's really three distinct services sharing the same fibre. This architecture is one of the reasons Movistar TV and phone continue working independently of your Internet traffic.
Q: of the 255 adresses of that router, some are reserved. There is the DHCP range, but I think there is another reserved for TV or something
Yes, there is. The HGU uses parts of the `192.168.1.0/24` subnet internally, although the exact assignments vary slightly by firmware and model.
A typical Movistar HGU ends up looking something like this:
| Address/range | Purpose |
| ------------------------------ | ------------------------------------------------- |
| `192.168.1.1` | Router LAN interface (default gateway) |
| `192.168.1.2`–`192.168.1.31` | Reserved for static devices and internal services |
| `192.168.1.33`–`192.168.1.254` | DHCP pool (default) |
The interesting part is what happens with the addresses below `.32`.
### IPTV decoder
The TV decoder normally receives an address **outside the normal DHCP pool**. Depending on the firmware, you'll often see it around:
* `192.168.1.200+`, or
* a reserved low address such as `.3`, `.4`, etc.
The router recognizes the decoder (by MAC address and DHCP options) and gives it a specific lease rather than treating it like an ordinary client.
### Internal interfaces
The HGU also creates several virtual interfaces that don't correspond to physical LAN ports. Some firmwares assign them addresses on the LAN subnet for:
* IPTV control
* IGMP proxy
* multicast relay
* management
These addresses are usually hidden from the web interface.
### Hidden DHCP reservations
The DHCP server is not simply "free addresses from .33 onward". It also has a table of **reserved MAC addresses** for Movistar equipment:
* TV decoder(s)
* Wi-Fi extenders (Movistar Amplificador/Smart WiFi)
* sometimes internal management devices
These reservations are invisible in the normal configuration pages.
### Why start at `.33`?
Movistar deliberately leaves the first 32 addresses available because network administrators often want to assign static IPs manually:
```
192.168.1.1 Router
192.168.1.2 NAS
192.168.1.3 Printer
192.168.1.4 Home Assistant
...
192.168.1.32 Reserved
192.168.1.33+ DHCP
```
So although the router itself isn't using all of `.2`–`.32`, it avoids allocating them dynamically.
---
One subtle point is that **the TV traffic itself is not carried over a separate IP subnet**. People sometimes assume there's a hidden `192.168.x.x` network for IPTV, but there isn't. The isolation happens at **Layer 2** (VLAN 2), and once the packets reach your LAN they're multicast IP packets on the same Ethernet segment. The decoder simply gets a normal IPv4 address on your LAN, then joins multicast groups via IGMP.
If you're asking because you've seen references to "reserved addresses for TV", I suspect you're remembering older Imagenio documentation. Early Movistar routers did indeed reserve specific LAN addresses for the set-top box, but modern HGUs rely much more on **MAC-based DHCP reservations** than on fixed IP numbers.
------------
DHCP config in my router was from 33 to 200. So I moved it to 192.168.2.* to have more.
--
Cheers,
Carlos E.R.
ES🇪🇸, EU🇪🇺;
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Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-29 23:23 -0400
Re: Multi-Networking in Linux - Multiple Subnets rbowman <bowman@montana.com> - 2026-07-30 04:14 +0000
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-30 23:38 -0400
Re: Multi-Networking in Linux - Multiple Subnets rbowman <bowman@montana.com> - 2026-07-31 05:31 +0000
Re: Multi-Networking in Linux - Multiple Subnets Richard Kettlewell <invalid@invalid.invalid> - 2026-07-31 09:44 +0100
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 12:19 +0100
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-30 12:37 +0200
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 13:42 +0200
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-30 13:58 +0200
Re: Multi-Networking in Linux - Multiple Subnets Robert Heller <heller@deepsoft.com> - 2026-07-30 12:14 +0000
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:36 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-30 13:25 +0100
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:37 +0200
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 18:43 +0200
Re: Multi-Networking in Linux - Multiple Subnets rbowman <bowman@montana.com> - 2026-07-30 19:22 +0000
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 21:53 +0200
Re: Multi-Networking in Linux - Multiple Subnets rbowman <bowman@montana.com> - 2026-07-31 05:08 +0000
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-31 01:16 -0400
Re: Multi-Networking in Linux - Multiple Subnets rbowman <bowman@montana.com> - 2026-07-31 08:00 +0000
Re: Multi-Networking in Linux - Multiple Subnets Robert Heller <heller@deepsoft.com> - 2026-07-30 20:07 +0000
Re: Multi-Networking in Linux - Multiple Subnets rbowman <bowman@montana.com> - 2026-07-31 05:14 +0000
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:38 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 12:46 +0100
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:57 +0200
Re: Multi-Networking in Linux - Multiple Subnets - Movistar "docs" "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 14:25 +0200
Re: Multi-Networking in Linux - Multiple Subnets Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-07-30 21:18 +0000
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-30 23:50 -0400
Re: Multi-Networking in Linux - Multiple Subnets Robert Riches <spamtrap42@jacob21819.net> - 2026-07-31 04:06 +0000
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-31 00:34 -0400
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:50 +0200
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 14:51 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 14:37 +0100
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:43 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 12:50 +0100
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 14:00 +0200
Re: Multi-Networking in Linux - Multiple Subnets Robert Heller <heller@deepsoft.com> - 2026-07-30 11:59 +0000
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-30 13:32 +0100
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 18:44 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-30 18:06 +0100
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 21:54 +0200
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-30 23:48 -0400
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 08:15 +0200
Re: Multi-Networking in Linux - Multiple Subnets Lawrence D’Oliveiro <ldo@nz.invalid> - 2026-07-31 06:53 +0000
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 14:52 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 12:10 +0100
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 15:04 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 14:42 +0100
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 16:24 +0200
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 14:04 +0200
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 15:06 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 14:42 +0100
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 16:25 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 15:34 +0100
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-30 13:24 +0100
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 08:16 +0200
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-31 12:15 +0100
Re: Multi-Networking in Linux - Multiple Subnets Andy Burns <usenet@andyburns.uk> - 2026-07-30 14:53 +0100
Re: Multi-Networking in Linux - Multiple Subnets The Natural Philosopher <tnp@invalid.invalid> - 2026-07-30 14:59 +0100
Re: Multi-Networking in Linux - Multiple Subnets Andy Burns <usenet@andyburns.uk> - 2026-07-30 15:06 +0100
Re: Multi-Networking in Linux - Multiple Subnets Rich <rich@example.invalid> - 2026-07-30 14:35 +0000
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 18:46 +0200
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-30 23:45 -0400
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 13:51 +0200
Re: Multi-Networking in Linux - Multiple Subnets "Stanislav N. aka pztrn" <no@email.please> - 2026-07-31 17:28 +0500
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-31 15:07 +0200
Re: Multi-Networking in Linux - Multiple Subnets c186282 <c186282@nnada.net> - 2026-07-30 23:43 -0400
Re: Multi-Networking in Linux - Multiple Subnets "Carlos E. R." <robin_listas@es.invalid> - 2026-07-31 14:28 +0200
Re: Multi-Networking in Linux - Multiple Subnets Marc Haber <mh+usenetspam2616@zugschl.us> - 2026-07-30 13:48 +0200
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