06-10-2011 04:17 AM - edited 03-07-2019 12:44 AM
I'm using a Cisco 877W router which connects to a private broadband network using PPPoA. I have installed many other 800 series routers on broadband lines successfully so am familiar with DSL but cannot resolve this issue.
When i connect my router to the line i get a solid Carrier detect light and when doing a debug atm events i get "showtime" so all good. However when i debug ppp negotiation i am not able to authenticate. It is not that my CHAP/PAP username and password is wrong its that i don't even get to that point.
The router continually does a confreq over 30 times which times out which would indicate no response from the ISP:
000040: *May 4 11:54:51.157 BST: Vi2 LCP: O CONFREQ [REQsent] id 44 len 10
000041: *May 4 11:54:51.157 BST: Vi2 LCP: MagicNumber 0x75D5C4D8 (0x050675D5C4D8)
000042: *May 4 11:54:53.173 BST: Vi2 LCP: Timeout: State REQsent
However after 30+ time i eventually get a response (4 minutes later):
000179: *May 4 11:58:11.864 BST: Vi2 LCP: O CONFREQ [ACKsent] id 84 len 10
000180: *May 4 11:58:11.864 BST: Vi2 LCP: MagicNumber 0x75D8D4DD (0x050675D8D4DD)
000181: *May 4 11:58:11.896 BST: Vi2 LCP: I CONFACK [ACKsent] id 84 len 10
000182: *May 4 11:58:11.896 BST: Vi2 LCP: MagicNumber 0x75D8D4DD (0x050675D8D4DD)
000183: *May 4 11:58:11.896 BST: Vi2 LCP: State is Open
000184: *May 4 11:58:11.896 BST: Vi2 PPP: Phase is AUTHENTICATING, by the peer
000185: *May 4 11:58:11.896 BST: Vi2 CHAP: I CHALLENGE id 57 len 38 from "ERX15.Birmingham3"
000186: *May 4 11:58:15.960 BST: Vi2 CHAP: I CHALLENGE id 58 len 38 from "ERX15.Birmingham3"
000187: *May 4 11:58:20.061 BST: Vi2 CHAP: I CHALLENGE id 59 len 38 from "ERX15.Birmingham3"
000188: *May 4 11:58:21.913 BST: Vi2 AUTH: Timeout 1
000189: *May 4 11:58:24.161 BST: Vi2 CHAP: I CHALLENGE id 60 len 38 from "ERX15.Birmingham3"
000190: *May 4 11:58:28.262 BST: Vi2 CHAP: I CHALLENGE id 61 len 38 from "ERX15.Birmingham3"
000191: *May 4 11:58:31.926 BST: Vi2 AUTH: Timeout 2
000192: *May 4 11:58:32.358 BST: Vi2 CHAP: I CHALLENGE id 62 len 38 from "ERX15.Birmingham3"
000193: *May 4 11:58:36.459 BST: Vi2 CHAP: I CHALLENGE id 63 len 38 from "ERX15.Birmingham3"
000194: *May 4 11:58:40.559 BST: Vi2 CHAP: I CHALLENGE id 64 len 38 from "ERX15.Birmingham3"
000195: *May 4 11:58:41.944 BST: Vi2 AUTH: Timeout 3
000196: *May 4 11:58:44.660 BST: Vi2 CHAP: I CHALLENGE id 65 len 38 from "ERX15.Birmingham3"
000197: *May 4 11:58:48.773 BST: Vi2 CHAP: I CHALLENGE id 66 len 38 from "ERX15.Birmingham3"
000198: *May 4 11:58:51.961 BST: Vi2 AUTH: Timeout 4
000199: *May 4 11:58:52.869 BST: Vi2 CHAP: I CHALLENGE id 67 len 38 from "ERX15.Birmingham3"
000200: *May 4 11:58:56.966 BST: Vi2 LCP: I TERMREQ [Open] id 120 len 4
000201: *May 4 11:58:56.966 BST: Vi2 LCP: O TERMACK [Open] id 120 len 4
000202: *May 4 11:58:56.966 BST: Vi2 PPP: Sending Acct Event[Down] id[4]
000203: *May 4 11:58:56.970 BST: Vi2 PPP: Phase is TERMINATING
000204: *May 4 11:58:58.970 BST: Vi2 LCP: Timeout: State TERMsent
000205: *May 4 11:58:58.970 BST: Vi2 LCP: State is Closed
000206: *May 4 11:58:58.970 BST: Vi2 PPP: Phase is DOWN
Now to me this indicates an inbound packet from the ISP but now my router doesn't respond.
Is this a configuration issue with my router or an ISP problem. I have read the Cisco DSL Troubleshooting for PPPoA document but it doesn't cover this. my configuration is below:
interface ATM0
no ip address
no ip mroute-cache
no shut
atm vc-per-vp 64
no atm ilmi-keepalive
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1
interface Dialer1
ip address 10.x.x.1 255.255.255.254
ip inspect myfw out
ip virtual-reassembly
encapsulation ppp
dialer pool 1
dialer-group 1
ppp authentication chap pap callin
ppp chap hostname xxxx
ppp chap password yyyy
ppp pap sent-username xxxx password yyyy
ppp ipcp dns request
ppp ipcp wins request
hold-queue 224 in
thanks Alex
06-10-2011 06:02 AM
Which IOS are you using ?
Can you send "show dsl itnterface", "show int atm0". To rule out layer 1 issues.
06-13-2011 12:52 AM
I had the PSTN provider come out to check the line and they confirmed it was ok. The fact i get a carrier detect should mean the line is ok. I'm just a bit confused that i do occassionally see some traffic from the ISP but don't complete the PPP negotiation.
IOS - c870-advsecurityk9-mz.124-24.T4.bin
sh int atm0 -
ATM0 is up, line protocol is up
Hardware is MPC ATMSAR (with Alcatel ADSL Module)
MTU 4470 bytes, sub MTU 4470, BW 448 Kbit/sec, DLY 820 usec,
reliability 255/255, txload 1/255, rxload 1/255
Encapsulation ATM, loopback not set
Encapsulation(s): AAL5 AAL2, PVC mode
10 maximum active VCs, 64 VCs per VP, 1 current VCCs
VC Auto Creation Disabled.
VC idle disconnect time: 300 seconds
Last input never, output 00:00:01, output hang never
Last clearing of "show interface" counters 00:02:58
Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
Queueing strategy: Per VC Queueing
5 minute input rate 0 bits/sec, 0 packets/sec
5 minute output rate 0 bits/sec, 0 packets/sec
15 packets input, 485 bytes, 0 no buffer
Received 0 broadcasts, 0 runts, 0 giants, 0 throttles
0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort
33 packets output, 525 bytes, 0 underruns
0 output errors, 0 collisions, 0 interface resets
0 unknown protocol drops
0 output buffer failures, 0 output buffers swapped out
sh dsl interface -
ATM0
Alcatel 20190 chipset information
ATU-R (DS) ATU-C (US)
Modem Status: Showtime (DMTDSL_SHOWTIME)
DSL Mode: ITU G.992.1 (G.DMT) Annex A
ITU STD NUM: 0x03 0x1
Vendor ID: 'STMI' 'ALCB'
Vendor Specific: 0x0000 0x0000
Vendor Country: 0x0F 0x0F
Chip ID: C196P (1) DFE BOM: DFE3.0 Annex A (1)
Capacity Used: 100% 59%
Noise Margin: 8.0 dB 18.0 dB
Output Power: 15.5 dBm 12.0
dBm Attenuation: 52.0 dB 31.5 dB
FEC ES Errors: 0 0
ES Errors: 23 1
SES Errors: 0 0
LOSES Errors: 0 0
UES Errors: 0 0
Defect Status: None None Last Fail Code: None Watchdog Counter: 0xAB Watchdog Resets: 0 Selftest Result: 0x00 Subfunction: 0x00
Interrupts: 8252 (0 spurious)
PHY Access Err: 0
Activations: 1
LED Status: ON
LED On Time: 100
LED Off Time: 100
Init FW: init_AMR-3.0.014_no_bist.bin
Operation FW: AMR-3.0.014.bin
FW Source: embedded
FW Version: 3.0.14 Interleave Fast Interleave Fast
Speed (kbps): 1888 0 448 0
Cells: 13620 0 337927022 0
Reed-Solomon EC: 35751 0 0 0
CRC Errors: 25 0 6 0
Header Errors: 17 0 0 0
Total BER: 7419E-12 0E-0
Leakage Average BER: 9931E-12 0E-0
ATU-R (DS) ATU-C (US)
Bitswap: enabled enabled
Bitswap success: 0 0
Bitswap failure: 0 0
LOM Monitoring : Disabled
DMT Bits Per Bin 000: output omitted by alex fray
Training log buffer capability is not enabled
06-13-2011 01:09 AM
The circuit has very high attenuation and quite a few errors.
I think there is layer 1 problem here.
However the router also responds strangely to PPP, can you try a different IOS ?
06-13-2011 03:10 AM
What is a good db range for attenuation?
i upgraded the IOS from T4 to T5 (c870-advsecurityk9-mz.124-24.T5.bin ) but still no joy, same result.
06-13-2011 03:37 AM
One random link, you can find more by searching.
http://www.naschenweng.info/2008/10/16/adsl-significance-of-snr-and-attenuation
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