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Cable modem is online but CMTS can't ping , check status on DHCP PNR , CNR available

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anhlt
Cable modem is online but CMTS can't ping , check status on DHCP PNR , CNR available
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Hi every body ,
I am a Engineer IT operation CMTS , i have a trouble like the subject of topic : The cable modem is online but CMTS can't ping , so we can't get the infomation of PWR , Mer , ... cable modem via SNMP - command line "cable modem remote query" . when i check the status on DHCP PNR , CNR of MAC address cable modem , it is avaible . So what is the reason here ? The communication between CM - CMTS - PNR . The CPE of CM connect internet normal .
Please help me to check it , sr about not good English .

Some log :

10K-NGOCKHANH-04#show cable modem 80:29:94:bb:d1:7f
D
MAC Address IP Address I/F MAC Prim RxPwr Timing Num I
State Sid (dBmv) Offset CPE P
8029.94bb.d17f 172.38.194.79 C7/0/2/U0 online 9 5.00 1040 1 N

10K-NGOCKHANH-04#show cable modem 80:29:94:bb:d1:7f cpe
IP address MAC address Dual IP Device Class
100.66.194.101 f4f2.6d84.8c87 N Host

10K-NGOCKHANH-04#ping 172.38.194.79

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.38.194.79, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

10K-NGOCKHANH-04#ping 100.66.194.101

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 100.66.194.101, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/8 ms

10K-NGOCKHANH-04#show cable modem remote-query | include 8029.94bb.d17f
8029.94bb.d17f 0.0 0.0 0.0 0 YES 172.38.194.79

Thanks!

kwesibrunee
the most likely cause is an

the most likely cause is an incorrect gateway on the modem. Check your dhcp settings and make sure the gateway your handing the modems is legit and not being blocked by an ACL.

anhlt
Some cable modems same

Some cable modems same network of interface Bundle are normal , no ACL is applied . The issues are in some cable modems, not at all .

mbowe
Need more information

172.38.x.x is not a private IP range

Show the configuration from your bundle interface

Show the configuration of your CM DHCP scope

anhlt
Hi guy,

Hi guy,
i send you config on CMTS and DHCP :

interface Bundle1.3
description "Giganet-Home2"
ip address 100.66.192.1 255.255.240.0 secondary
ip address 172.38.192.1 255.255.240.0
cable source-verify dhcp
cable dhcp-giaddr policy
cable helper-address 172.20.53.228
end

10K-NGOCKHANH-04#ping 172.20.53.228 source 172.38.192.1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.20.53.228, timeout is 2 seconds:
Packet sent with a source address of 172.38.192.1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms

File attachments: 
oss-iris
Check config file of the cm

Check config file of the cm for access

JMH
This may not help.... but

This may not help.... but have experienced this (BSR64K), and simply resetting the modem has caused the modems to start pinging again.

uscallesen
Signal ?

Remember the basics - The cable modem is online, using which modulation for docsis signaling ?

It's not uncommon for a modem to be able to registerer with very poor signal levels if the docsis maintenance traffic is running QPSK - Your data traffic to the modem is probably using a higher modulation (QAM16/QAM64) ?

Quick way to test for this is to do a docsis ping to the modem - does that succeed ? (Sorry cant remember the cisco syntax - ping docsis maybe ?

docsis