Kitz ADSL Broadband Information
adsl spacer  
Support this site
Home Broadband ISPs Tech Routers Wiki Forum
 
     
   Compare ISP   Rate your ISP
   Glossary   Glossary
 
Please login or register.

Login with username, password and session length
Advanced search  

News:

Pages: 1 2 [3] 4

Author Topic: BRAS IPv4 address  (Read 1734 times)

Terrydaktal

  • Just arrived
  • *
  • Posts: 10
Re: BRAS IPv4 address
« Reply #30 on: December 02, 2018, 05:25:58 AM »

https://www.gabriel.urdhr.fr/2015/02/15/broadband-protocol-stack/ check the U interface weaver. If they don't use PPP I can only assume they're using 802.1x authentication
Logged

CarlT

  • Reg Member
  • ***
  • Posts: 951
  • Next generation network design and deployment
Re: BRAS IPv4 address
« Reply #31 on: December 02, 2018, 07:49:43 AM »

Nah. Can be done via DHCP options, MAC address or simply the CVLAN the traffic arrives on. Fair bet that the device connected to a customer's assigned DSLAM port is them.

Note BT Retail and the ability to use any username and password. BTW just uses the domain to pre-auth and that's all that's needed.
Logged
-----
Deploying better networks, not just faster ones.

Weaver

  • Addicted Kitizen
  • *****
  • Posts: 6557
  • Retd sw dev; A&A; 4 ◊ 7km ADSL2; IPv6; Firebrick
Re: BRAS IPv4 address
« Reply #32 on: December 02, 2018, 08:27:28 AM »

I agree with what Carl said - I was going to say that I seem to vaguely remember that some non-BT ISPs who have their own hardware in the exchange and so can do whatever they like do use DHCP from a remote DHCP server to replace certain functions that are otherwise delivered by PPP. This sometimes involves extensions to DHCP, which can have all sorts of options anyway, is very extensible. Thatís only for IPv4 tho. I donít know what the story is for IPv6 with such ISPs, canít remember. In a case like that, someoneís router, which is acting as a local DHCP(v4) server for client machines on the LAN, is in fact acting as a relay in part. I have read the odd vague mention of such set-ups, but I donít really know much about this.

As for IPv6, I use BT and my IPv6-related stuff is iirc entirely set up by static configuration so no need for any network info services. I do get IPv6CP over PPP iirc from my ISP Andrews and Arnold, and there possibly is config info actually available through it in my case, I forget. I am also unsure as I canít think of a single case where I use any such network-supplied info for IPv6 config. I, like most people who have PPP, do get config info supplied for IPv4 via IPCP over PPP, but I donít think I myself even use any of it.
Logged

j0hn

  • Kitizen
  • ****
  • Posts: 1976
Re: BRAS IPv4 address
« Reply #33 on: December 02, 2018, 02:03:00 PM »

https://www.gabriel.urdhr.fr/2015/02/15/broadband-protocol-stack/ check the U interface weaver. If they don't use PPP I can only assume they're using 802.1x authentication

Talktalk use IPoE with their own FTTC customers.
ISP's who wholesale Talktalk business are limited to PPP still.

Not 100% how they authenticate but there's certainly no credentials or Mac address from a fixed device.

Sky use DHCP Option 61 (they call it MER?) to authenticate.

Many many many modern broadband networks don't use PPP now. It's terribly inefficient when you start getting into higher throughput brackets.

OpenReach intended on ditching PPP for Ultrafast services (G.Fast/FTTP) but must have changed their mind.
Logged
BT FTTC 55/10 ECI now Huawei cab
Zyxel VMG1312-B10A bridge mode with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

Terrydaktal

  • Just arrived
  • *
  • Posts: 10
Re: BRAS IPv4 address
« Reply #34 on: December 04, 2018, 10:38:31 AM »

Thanks, didn't think about dhcp authentication. BTW, i'm still not entirely sure about cvlans and svlans, just to get this straight, cvlan applied as it egresses from the street MSAN, SVLAN applied as it egresses through the GEA cable link..?
Logged

CarlT

  • Reg Member
  • ***
  • Posts: 951
  • Next generation network design and deployment
Re: BRAS IPv4 address
« Reply #35 on: December 04, 2018, 12:02:10 PM »

Thanks, didn't think about dhcp authentication. BTW, i'm still not entirely sure about cvlans and svlans, just to get this straight, cvlan applied as it egresses from the street MSAN, SVLAN applied as it egresses through the GEA cable link..?

https://www.btplc.com/SINet/sins/pdf/498v7p5.pdf
Logged
-----
Deploying better networks, not just faster ones.

j0hn

  • Kitizen
  • ****
  • Posts: 1976
Re: BRAS IPv4 address
« Reply #36 on: December 04, 2018, 12:04:33 PM »

It's just a virtual way to split and manage traffic, particularly with different priorities.

The street MSANs are only operating as DSLAM's.
Only equipment in the exchange is used as a MSAN.

Logged
BT FTTC 55/10 ECI now Huawei cab
Zyxel VMG1312-B10A bridge mode with 1508 MTU + Asus RT-AC68U running Asuswrt-Merlin

kitz

  • Administrator
  • Senior Kitizen
  • *
  • Posts: 31690
  • Trinity: Most guys do.
    • http://www.kitz.co.uk
Re: BRAS IPv4 address
« Reply #37 on: December 05, 2018, 03:27:44 PM »

Basically DSLAM  (Digital Subscriber Line Access Multiplexer) Multiplexes DSL connections
MSANs (Multi-Service Access Node) Multiplexes DSL and connects telephony & IPTV to the SP core.

FTTC cabs only deal with xDSL thus contain DSLAMs. 
 
MSANs in the exchange (ie such as those used for adsl LLU) also have telephony interfaces. 
 
Logged
Please do not PM me with queries for broadband help as I may not be able to respond.
-----
How to get your router line stats :: ADSL Exchange Checker

Weaver

  • Addicted Kitizen
  • *****
  • Posts: 6557
  • Retd sw dev; A&A; 4 ◊ 7km ADSL2; IPv6; Firebrick
Re: BRAS IPv4 address
« Reply #38 on: December 05, 2018, 07:09:36 PM »

Ah, telephony is the Ďmultií bit. I had somehow never picked that up. Many thanks!
Logged

andrew-AAISP

  • ISP Rep
  • Member
  • *
  • Posts: 28
    • aa.net.uk
Re: BRAS IPv4 address
« Reply #39 on: December 06, 2018, 08:48:37 AM »

Until some months back I used to see entries in the BRAS column of AAís clueless.aa.net control server which were names of the relevant BRAS that each of my three links was ultimately connected to. Then it changed, the names are now gone and all three show 213.1.180.152.

We show the name of the BRAS if we know it, we work out the name if there is reverse DNS set. In this case there isn't any reverse DNS for the IP address (yet) though. Having reverse DNS is useful and interesting, but BTW don't always add them; also sounds like this may be a new IP address if it has changed recently.
Logged
A&A

Weaver

  • Addicted Kitizen
  • *****
  • Posts: 6557
  • Retd sw dev; A&A; 4 ◊ 7km ADSL2; IPv6; Firebrick
Re: BRAS IPv4 address
« Reply #40 on: December 06, 2018, 09:04:30 AM »

Thanks Andrew. I wondered why BT had changed it, whether it was just routine upgrading of kit or whether there had been a real redirection, rerouting of the geographical location.
Logged

Terrydaktal

  • Just arrived
  • *
  • Posts: 10
Re: BRAS IPv4 address
« Reply #41 on: December 09, 2018, 05:07:22 AM »

When I wrote earlier about SDH, I'm pretty sure that it uses GTC + GEM between the ONU in the FTTC cab and the OLT, unless i'm mistaken
Logged

CarlT

  • Reg Member
  • ***
  • Posts: 951
  • Next generation network design and deployment
Re: BRAS IPv4 address
« Reply #42 on: December 09, 2018, 11:55:22 AM »

ONU in the cabinet? They use 1000base-BX connecting to ports on the cabinet's supervisor board. Nothing more complicated than that.

Some use WDM but same story, BX on different wavelengths multiplexed by external kit in the cabinet so it hits the DSLAM as simple BX.

Just saying you think they use GPON rather than trying to describe every protocol in the stack is fine.

The OLTs are multipurpose kit. They feed subscribers directly via PON ports and cabinets and indeed CableLinks to CPs via point to point Ethernet line cards. The Huawei OLTs can be the L2S.
Logged
-----
Deploying better networks, not just faster ones.

Terrydaktal

  • Just arrived
  • *
  • Posts: 10
Re: BRAS IPv4 address
« Reply #43 on: December 10, 2018, 11:16:35 AM »

I don't have any experience working at ISPs or the equipment but it's always been a gap in my knowledge that I've wanted to fill, I'm slowly ascertaining more and more through research, postulation, forums but it's never as good as actual pertinent hands on experience.

So openreach uses P2P not a GPON then for FTTC, interesting, I believe FTTP modems use GPON. Again with the SVLAN /CVLANs I understand the significance of a QinQ in GPON, the SVLAN provides a mapping to a GEM port and I believe it allows for flood domain shrinking to a specific GEM port associated with the SVLAN, and the CVLAN provides 801.1p CoS to the modem and service identification but with 1000base BX, despite reading the source you sent and a few others I haven't fully grasped the significance of a SVLAN in QinQ, I know the CVLAN provides 802.1p scheduling at the DSLAM and service identification at the modem but the SVLAN, why, could you perhaps state the importance of it, it seems to be grouping for different services again for the SP, what's the significance of this? is it used for determining the wavelength to use in the WDM kit? I. E.  For iptv.
Logged

CarlT

  • Reg Member
  • ***
  • Posts: 951
  • Next generation network design and deployment
Re: BRAS IPv4 address
« Reply #44 on: December 10, 2018, 01:09:50 PM »

Again I think rather than reciting buzzwords and acronyms some thought about how networks are built would be a good plan. Serious case of trying to run before walking which will cause more confusion.

IPTV isn't going to use a separate wavelength. The whole point is that it's TV over IP. It uses the same IP network as broadband services. If it were on a separate wavelength it wouldn't be IPTV, it'd be using RFoG.

CVLANs face customers. SVLANs face service providers and have many CVLANs inside them. A single Service VLAN can carry 4096 Customer VLANs inside it. Service aggregation is a good thing. Rather than having thousands of CVLAN mappings between individual customers and service providers Openreach kit can use the SVLAN to make the decisions which CableLink and, hence, CP, they should switch the traffic too.

There's also the issue that the VLAN header is only 12 bits long which means a maximum of 4096 VLANs per layer 2 domain. Q-in-Q increases this to 16.7 million which allows scale. Without Q-in-Q operators could only terminate 4095 GEA customers on each BRAS.
Logged
-----
Deploying better networks, not just faster ones.
Pages: 1 2 [3] 4