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Bandwidth Request Failure

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Anonymous (not verified)
Bandwidth Request Failure

Hello

I've got a Arris C3 CMTS and DOCSIS 2.0 compliant Cable Modems.

DOCSIS 2.0 with BPI+ mode seems to be fully operational but I keep on getting "Bandwidth Request Failure" messages in the serial interface of the cable modem. I'm generally only running 5 or 6 modems at the same time with very little traffic.

I'm attaching my configurations.
Could anyone please tell me what I'm doing wrong?

Thanks!
Barney

My Cable Modem Configuration file is

Main
{
NetworkAccess 1;
BaselinePrivacy
{
AuthTimeout 10;
ReAuthTimeout 10;
AuthGraceTime 60;
OperTimeout 1;
ReKeyTimeout 1;
TEKGraceTime 60;
AuthRejectTimeout 60;
SAMapWaitTimeout 10;
SAMapMaxRetries 3;
}
MaxCPE 16;
UsServiceFlow
{
UsServiceFlowRef 1;
QosParamSetType 7;
SchedulingType 2;
}
DsServiceFlow
{
DsServiceFlowRef 2;
QosParamSetType 7;
}
GlobalPrivacyEnable 1;
ManufacturerCVC "CVC.cer.der";
SwUpgradeServer 192.168.15.2;
SwUpgradeFilename "signed_image1.bin";
}

My Arris C3 cable interface configuration:

interface Cable 1/0
cable utilization-interval 10
cable docsis10 max-traffic-burst 3044
cable insertion-interval automatic
cable sync-interval 10
cable ucd-interval 2000
cable max-ranging-attempts 16
cable sid-verify
cable downstream rate-limit
cable flap-list size 500
cable flap-list aging 259200
cable flap-list miss-threshold 6
cable flap-list insertion-time 180
cable downstream admission-control 100
no cable downstream admission-limit
! no description
! no shutdown
! mac-address 0013.11e9.bc53
load-interval 300
ip address 192.168.19.1 255.255.255.0
no allow-ip-only
ip ospf priority 0
management-access
tftp-server-access
no cable source-verify
arp-broadcast-echo
l2-broadcast-echo
l2-multicast-echo
ip-broadcast-echo
ip-multicast-echo
no l2-broadcast-throttle
throttle-credits initial 15 running 2
ip igmp enable
ip dhcp relay
ip dhcp relay information option
no ip dhcp relay validate renew
ip dhcp relay non-broadcast
ip dhcp relay non-broadcast information option
cable helper-address 192.168.15.2
cable dhcp-giaddr primary
cable downstream mac-mode docsis
cable downstream channel-width 6mhz
cable downstream frequency 525000000
cable downstream interleave-depth 32
cable downstream modulation 64qam
cable downstream power-level 62
no cable privacy accept-self-signed-certificate
cable privacy check-cert-validity-periods
cable privacy kek life-time 604800
cable privacy tek life-time 43200
no cable shared-secret

!no cable upstream 0 description
! no cable upstream 0 shutdown
cable upstream 0 mac-mode docsis

cable upstream 0 frequency 28000000
cable upstream 0 channel-width 6400000
cable upstream 0 power-level -4 fixed
cable upstream 0 low-power-offset -60
cable upstream 0 high-power-offset 60
cable upstream 0 group-id 1
cable upstream 0 plant-length 160
cable upstream 0 initial-ranging-delay 300
cable upstream 0 periodic-maintenance-interval 1000
cable upstream 0 short-periodic-maintenance-interval 100
cable upstream 0 minimum-unfrag-burst 600
cable upstream 0 admission-control 100
cable upstream 0 dominant-interval default
no cable upstream 0 admission-limit
cable upstream 0 voice-timeout 1
!no cable upstream 0.0 description
! no cable upstream 0.0 shutdown
cable upstream 0.0 channel-type ATDMA
cable upstream 0.0 modulation-profile 3
no cable upstream 0.0 pre-equalization
cable upstream 0.0 minislot-size 4
cable upstream 0.0 trigger-index 0
cable upstream 0.0 snr-timeconstant 4
cable upstream 0.0 mer-timeconstant 8
cable upstream 0.0 rng-prm-guard 1
cable upstream 0.0 nrng-prm-guard 2
no cable upstream 0.0 ingress-cancellation
no cable upstream 0.0 impulse-mitigation
cable upstream 0.0 safe-config
no cable upstream 0.0 extended-frequency-detect
cable upstream 0.0 concatenation
cable upstream 0.0 fragmentation
cable upstream 0.0 data-backoff automatic
cable upstream 0.0 range-backoff automatic
cable upstream 0.0 contention-opp-latency 10000
cable upstream 0.0 contention-opps-with-data required
cable upstream 0.0 rate-limit
cable upstream 0.0 status activate

no ip directed-broadcast
no ip source-verify
no ip source-verify subif
ip l2-bg-to-bg-routing
ip verify-ip-address-filter

The Arris Upstream modulation profile that I use:

cable modulation-profile 3 request AdvPhy ATDMA 1 1536
cable modulation-profile 3 request AdvPhy preamble-type qpsk1
cable modulation-profile 3 request 0 16 0 8 64qam scrambler 338 no-diff 64 fixed
cable modulation-profile 3 initial AdvPhy ATDMA 1 1536
cable modulation-profile 3 initial AdvPhy preamble-type qpsk1
cable modulation-profile 3 initial 5 34 0 48 64qam scrambler 338 no-diff 640 fixed
cable modulation-profile 3 station AdvPhy ATDMA 1 1536
cable modulation-profile 3 station AdvPhy preamble-type qpsk1
cable modulation-profile 3 station 5 34 0 48 64qam scrambler 338 no-diff 384 fixed
cable modulation-profile 3 advPhyS AdvPhy ATDMA 1 1536
cable modulation-profile 3 advPhyS AdvPhy preamble-type qpsk1
cable modulation-profile 3 advPhyS 12 78 6 8 64qam scrambler 338 no-diff 104 shortened
cable modulation-profile 3 advPhyL AdvPhy ATDMA 1 1536
cable modulation-profile 3 advPhyL AdvPhy preamble-type qpsk1
cable modulation-profile 3 advPhyL 16 220 0 8 64qam scrambler 338 no-diff 104 shortened
cable modulation-profile 3 advPhyU AdvPhy ATDMA 1 1536
cable modulation-profile 3 advPhyU AdvPhy preamble-type qpsk1
cable modulation-profile 3 advPhyU 12 78 0 8 64qam scrambler 338 no-diff 104 shortened

Anonymous (not verified)
Bandwidth Request Failure

... "Bandwidth Request Failure" messages in the serial interface
^^^^^^^^^^

You meant cable interface?

What I missed in your CM config is bandwidth limitations.
Is is test environment and you just testing docsis 2.0 features?

IMHO, I`ll change the following parameters in your config:

Quote:cable upstream 0 plant-length 160

160 Km length of coax cable plant. Is it correct?
AFAIK, setting too high length is make US more robust but decrease overall bandwidth of US.

Quote:cable downstream modulation 64qam

What about qam256? Is it present in DOCSIS (in EuroDOCSIS it is)

astrit
Bandwidth Request Failure

Maybe it's becouse the CM doesn't have a good upstream SNR to serve the 6.4 MHz upstream channel. Look at the tx power of the CM ( recomandet 30 to 50). Also check the upstream SNR of the CM, for 6.4 Mhz channel I think it should be around 30 dB.

P.S. I'm intersted about arris C3 DOCSIS 2.0 CMTS. How much it would cost me?

Astrit

Anonymous (not verified)
Bandwidth Request Failure

Quote:I'm intersted about arris C3 DOCSIS 2.0 CMTS. How much it would cost me?

AFAIR, all C3 is DOCSIS 2.0 compatible at the moment.
The early models of C3 was equippet by 'BCM3138 Rev A2' upstream cards. They are not compatible with SCDMA modulation. TDMA&ATDMA modulation only.
At the moment, AFAIK, C3 goes with BCM3140 upstream cards, and it`s ATDMA/TDMA/SCDMA compatible.
In Russia, a bundle
C3 with 1DS/4US + 4.0.3 version of software costs nearly 16000 $.

Anonymous (not verified)
Bandwidth Request Failure

Hi,

Thank you for the advice.

It turned out that the two cable modems were given the same cable mac address by accident and thus there were conflicts at the MAC layer.

But I'm going to try out your suggestions on our networks soon because we only do development (we are not a service operator). Thus the maximum cable length will be no more than 100m! So we should be able to get very high upstream bit rates!

Astrit,
In South Africa our Arris C3 CMTS's price range was also in that range.

Thanks again!

astrit
Bandwidth Request Failure

I saw yesterday in specification sheet of C3 that it could have up to 6 upstream ports. I want to know does it have more than 6 logical upstream ports. Becouse in spec. sheet says that the cmts can handle 3000 registered modems, and with 6 upstream ports it will have 500 modems in one upstream ports, what I think is to much, becouse cisco recomands up to 250 CMs in one upstream port.

Thanks
Astrit

Anonymous (not verified)
Bandwidth Request Failure

C3 has three slots for US cards. Each card has 2 physical upstreams.
So every physical upstream can be devided on several logical upstreams (with the same width).
For example I use the following scheme
upstream 0.0 - tdma (qam16)
upstream 0.1 - tdma&atdma (qam64)
upsteram 0.2 - scdma (qam64)

and the same for the rest US channels.

so, totally I have 4x3=12 logical upstreams. All modems automatically choose preferred upstream depending on SNR parameters and so on.

The number - 3000 CM is theoretical maximum. something like best/ideal result for marketing purposes. In real environments practical maximum depends on your configuration - QoS settings, traffic shaping, amount of service flows per CM, trafic filters, etc.

In my practice, there was 600 CM per C3. After that it was nightmare for our tech.support because where was a storm of user calls appeals on delays. but as you can understand, we have complex config with logical upstreams and nearly 10 service flows per CM in DS and 10 in US.

For Motorola BSR1000 (max 2000 CM`s announced) we`ve received maximum 500 CM in DOCSIS 1.0 mode. each CM was limited up to 512Kbit/sec in DS and 256 kbit/sec in US. When all bandwidth 50/40 (4x10) was exhausted - BSR1000 hangs and reboot automatically :( so we had to move nearly a half of all the customers to another CMTS for improving stability of BSR :(
So, make a conclusion by yourself.

astrit
Bandwidth Request Failure

We as a cable ISP would like to buy some Arris C3. Could anybody of you send me any PDF documentation of this CMTS, any Functional and description or CLI comands?

Regards
Astrit

boombastic (not verified)
Bandwidth Request Failure

It`s better for you to request such a documentation from ARRIS directly.
(http://www.arrisi.com/contact_us/support/index.asp)

Imho, it`s better to look at Cisco CMTS.
Of course C3 a bit cheaper, but it`s very bad in routing mode (128 prefixes in routing table only, and max 16 ACL strings in any ACL), with default license C3 supports only 2 VLANs, and if you want to use OSPF/RIPv2 or more than 2 VLAN - you need two buy separate license (2000$ per license for OSPF, RIP,VLANs separately).
Of course software is also costs money :(
So totally for a complex configuration - price of C3 similar with the price of UBR

milelj
Bandwidth Request Failure

Hi,
we had same problem after installing new line card in cisco cmts, and reboot hepled. We later discovered that line card was of synchronization. Also you can try using higher frequency (32-34 MHz) and narrow channel width.

Best regards,

Mile