CPE DHCP difficulties on a THG540 in a Docsys 1.x enviroment | docsis.org

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CPE DHCP difficulties on a THG540 in a Docsys 1.x enviroment

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incinerator82
CPE DHCP difficulties on a THG540 in a Docsys 1.x enviroment

Hello all!

I'm quite new at the Docsys technology so please bare with me :) aka Docsys dummy ;)
(if you have a suggestion : docsys for dummy's. Please send me a intro or howto..)

network specs :

Nortel CMTS
os :
ARRIS MCNS Cable Modem Termination System
Software Version: 3.6.2

Provisioning :
Linux Debian distro
DHCP ( 2 pools, 1 for CM, 1 for CPE)
TFTPD
DNS
NNTP
MYSQL (DB with mac address + ip address CM network)

We're using a very default config with no BIN's!
Our basic config :
--
NetworkAcces = 1
ClassOfService =
ClassId = 1
MaxDownstreamRate = 1024000
MaxUpstreamRate = 128000
CoSPrivacyEnbale = 0
MaxCpeAllowd =1
--
Compiled with packet ace for uploads to the CM's

All is working properly with the Arris CM550 cable modems.
But when we deploy the THG540 THomson, the CM's are coming online but the CPE isn't able to get a DCHP request trough.

Our provisioning is NOT receiving any requests through the THG540.
Does the THG540 needs a DHCP OPTION 122 defined voor the ToD? (forget that, that's all about MTA)

Or am I missing the point?

Thanx for reply's.

wittmann
MaxCPE Issue

Hi,

The Arris CM550 is a CM and the Thomson THG540 is a CM with eMTA.

The eDOCSIS-Specification says a eMTA MUST count to the MaxCPE-Table. Thomson has a PrivateMib or TLV that make possible that the CM will not count the eMTA to the MaxCPE-Table but i haven't to hand right now.

After a bootup the eMTA is quicker 'online' as the CPE behind the Ethernet/USB (called CMCI = Cable Modem to Customer Interface) and fill immediately one "slot" in the MaxCPE-Table.

I don't know if you deactivating the eMTA during the DHCP-Option 122-subOpt 1 with 0.0.0.0 at the Bootp-Reply for the CM-Part. Then the eMTA should be set shutdown and will not come ready to bootup herself and will not count against the MaxCPE-Table.

For a quick test you can set the MaxCPE-Table to MaxCPE 2, then your CPEs behind the THG540 should work.

regards,

wittmann

P.S. Sorry for my poor english ;)

incinerator82
I'm going to test it! First

I'm going to test it!
First i will try to raise the CPE acces, for a quick check.
Then i have to investigate how to disable the eMTA (since we won't use that part, problably it is already there for we don't see any dhcp req.).

i'll keep you informed

grtz John

ps Your english is good enough for me ;)

incinerator82
solved

a little late reply,

it seems that we had thompson 540 euro docsys and we're using docsys.
So this issue is not related anymore.. the funny thing is, normally the thompson should be able to come online. cause of the docsys mismatch...

thnx John

wittmann
Default Shutdown of eMTA

For default shutdown of a eMTA set the Opt122-SubOpt1 to 0.0.0.0.

Example for ISC-DHCP:

Define the Option122 in the dhcpd.conf:
[font=Courier][b]
option option-122 code 122 = string;
[/b][/font]

Then add 122 to the dhcp-parameter-request-list and the option122 with subopt 1 0.0.0.0:
[font=Courier][b]
class "cablemodem" {
match if
(substring(option dhcp-client-identifier, 1, 6) = option agent.remote-id);
option dhcp-parameter-request-list 1,2,3,4,7,12,15,66,67,[color=red]122[/color];
[color=red]option option-122 01:04:00:00:00:00;[/color]
}
[/b][/font]

regards,

wittmann

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