887VA - ADSL Performance problem

igotafix1 · ‎11-17-2015

Hi All,

I have a 887VA ISR router with very poor ADSL performance. WAN throughput is around 1mbit/s and often drops below 100kbp/s!

Testing I have done includes swapping the Cisco for a Huawei ADSL modem, connected to the same ADSL line. Throughput immediately jumps to around 12mbit/s.

To eliminate the possibility that config on the 887 is at fault, I connected it to the Huawei modem and tested throughput from hosts behind the Cisco. Same 12mbit/s.

So I am pretty sure the issue is with the 887 VDSL/ADSL controller or firmware. I would upgrade this but I don't have the necessary entitlements on Cisco.com.

Has anyone had an issue like this? Any suggestions / troubleshooting I can do? I enabled debug vdsl but couldn't make much sense of it.

Some relevant config is below:

interface ATM0
no ip address
no atm ilmi-keepalive
pvc 0 0/100
encapsulation aal5mux ppp dialer
dialer pool-member 1
!
interface Dialer0
mtu 1492
ip address negotiated
no ip redirects
no ip unreachables
ip nat outside
ip virtual-reassembly in
zone-member security INTERNET
encapsulation ppp
shutdown
dialer pool 1
dialer-group 1
ppp pap sent-username user@myisp password 7 xxx
ppp ipcp dns request
ppp ipcp route default
no cdp enable

Cisco IOS Software, C880 Software (C880DATA-UNIVERSALK9-M), Version 15.5(3)M, RELEASE SOFTWARE (fc1)

887#sh controllers vdsl 0
Controller VDSL 0 is DOWN

Daemon Status: Establishing Link

XTU-R (DS) XTU-C (US)
Chip Vendor ID: 'BDCM' 'IKNS'
Chip Vendor Specific: 0x0000 0x0001
Chip Vendor Country: 0xB500 0xB500
Modem Vendor ID: 'CSCO' ' '
Modem Vendor Specific: 0x4602 0x0000
Modem Vendor Country: 0xB500 0x0000
Serial Number Near: FGL162825C8 887VA-K9 15.5(3)M
Serial Number Far: ^A
Modem Version Near: 15.5(3)M
Modem Version Far: 0x0001

Modem Status: Idle

DSL Config Mode: ADSL
Trained Mode:
TC Mode: ATM
Selftest Result: 0x00
DELT configuration: disabled
DELT state: not running

Full inits: 6
Failed full inits: 0
Short inits: 0
Failed short inits: 0

Firmware Source File Name
-------- ------ ----------
VDSL default flash:vdsl.bin

Modem FW Version: 130208_1314-4.02L.03.A2pv6C038k1.d24g1
Modem PHY Version: A2pv6C038k1.d24g1
Trellis: ON ON
SRA: disabled disabled
SRA count: 0 0
Bit swap: enabled enabled

Training Log : Stopped
Training Log Filename : flash:vdsllog.bin

parkbenchit · ‎11-17-2015

Try this

show dsl interface atm 0

and you should see what speed it's actually syncing at

example:

DS Channel1 DS Channel0 US Channel1 US Channel0
Speed (kbps): 0 10487 0 596

this example is about 10Mb down and 0.5 up.

If your sync speed is ok - but the speedtest is still horrible - then try adjusting the MTU / MSS downwards

On the Dialer0 Interface

ip tcp adjust-mss 1300

and an mtu of similar.

Then reload and retest. If the issue has gone away, you can increase the MSS and MTU to the point where it breaks again.

It is possible (we've seen it) that the ISP has made some horrible "behind the scenes" alteration to their network that gives you an MTU blackhole.

Other (cheaper) routers automagically work this out - but the Cisco doesn't.

And that can mean you get connectivity and some throughput - but that as soon as reasonable load is put on the connection, large chunks of traffic disappear into the blackhole - giving you an apparently slow connection.

oh - and I just saw your PVC settings. UK settings tend to be as follows - but this might not apply to you.

interface ATM0
no ip address
no atm ilmi-keepalive

interface ATM0.1 point-to-point
pvc 0/38
encapsulation aal5mux ppp dialer
dialer pool-member 1

igotafix1 · ‎11-18-2015

Thanks for a post parkbenchit.

I tried changing the mss and mtu but it wouldn't change on the virtual-access interface:

887#sh int d0
Nov 18 09:59:08.362: %SYS-5-CONFIG_I: Configured from console by console d0
Dialer0 is up, line protocol is up (spoofing)
Hardware is Unknown
Internet address is XXXXXXX/32
MTU 1200 bytes, BW 56 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 255/255
Encapsulation PPP, LCP Closed, loopback not set
Keepalive set (10 sec)
DTR is pulsed for 1 seconds on reset
Interface is bound to Vi2
<snip>
Bound to:
Virtual-Access2 is up, line protocol is up
Hardware is Virtual Access interface
MTU 1500 bytes, BW 992 Kbit/sec, DLY 20000 usec,
reliability 255/255, txload 1/255, rxload 16/255
Encapsulation PPP, LCP Open
Open: IPCP
PPPoATM vaccess, cloned from Dialer0
Vaccess status 0x44
Bound to ATM0 VCD: 1, VPI: 0, VCI: 100, loopback not set
Keepalive set (10 sec)

Seemed to make very little difference to performance like this. I tried setting this on atm0 too, but couldn't edit vi2.

887(config)#int vi2
% Please use virtual template to configure your virtual access
887(config)#

887#sh dsl interface atm 0
^
% Invalid input detected at '^' marker.

887#sh controllers vdSL 0 bit-alloc
Controller VDSL 0 is UP

Daemon Status: Up

XTU-R (DS) XTU-C (US)
Chip Vendor ID: 'BDCM' 'IKNS'
Chip Vendor Specific: 0x0000 0x0001
Chip Vendor Country: 0xB500 0xB500
Modem Vendor ID: 'CSCO' ' '
Modem Vendor Specific: 0x4602 0x0000
Modem Vendor Country: 0xB500 0x0000
Serial Number Near: FGL162825C8 887VA-K9 15.5(3)M
Serial Number Far:
Modem Version Near: 15.5(3)M
Modem Version Far: 0x0001

Modem Status: TC Sync (Showtime!)

DSL Config Mode: ADSL
Trained Mode: G.992.1 (ADSL) Annex A
TC Mode: ATM
Selftest Result: 0x00
DELT configuration: disabled
DELT state: not running

Full inits: 1
Failed full inits: 0
Short inits: 0
Failed short inits: 0

Firmware Source File Name
-------- ------ ----------
VDSL default flash:vdsl.bin

Modem FW Version: 130208_1314-4.02L.03.A2pv6C038k1.d24g1
Modem PHY Version: A2pv6C038k1.d24g1
Trellis: ON ON
SRA: disabled disabled
SRA count: 0 0
Bit swap: enabled enabled
Bit swap count: 0 0
Line Attenuation: 6.0 dB 7.5 dB
Signal Attenuation: 6.0 dB 0.0 dB
Noise Margin: 15.3 dB 12.0 dB
Attainable Rate: 8676 kbits/s 1120 kbits/s
Actual Power: 13.8 dBm 12.5 dBm
Total FECC: 0 0
Total ES: 0 0
Total SES: 0 0
Total LOSS: 0 0
Total UAS: 28 28
Total LPRS: 0 0
Total LOFS: 0 0
Total LOLS: 0 0

DS Channel1 DS Channel0 US Channel1 US Channel0
Speed (kbps): 0 6688 0 992
SRA Previous Speed: 0 0 0 0
Previous Speed: 0 0 0 0
Total Cells: 0 7558183 0 0
User Cells: 0 21932 0 0
Reed-Solomon EC: 0 0 0 0
CRC Errors: 0 0 0 0
Header Errors: 0 0 0 0
Interleave (ms): 0.00 16.00 0.00 1.00
Actual INP: 0.00 2.00 0.00 0.06

Training Log : Stopped
Training Log Filename : flash:vdsllog.bin

I had a cisco 837 on hand so i connected that to the ADSL line. Performance was half of that of the Huawei (around 7mbit/s). That's with the default mtu and mss of 1500.

The 887 couldn't do more than 1mbit/s.

pvc 0 0/100 is correct for NZ. I don't really need to create a sub-interface on atm0 do I? Might try that next.

Starting to think the VDSL controller is faulty?? I'd like to upgrade the firmware but getting hold of it proving difficult.

If you have any other ideas I'm keen to hear. Thanks again.

parkbenchit · ‎11-18-2015

A sync speed of 6.6Mb down and 0.9 up?

Feels like perhaps it's doing ADSL rather than VDSL. If the line supports ADSL, then by default the 887VA's will do ADSL. You have to explicitly tell it to do VDSL

From your text above - I think this bit confirms it

Trained Mode: G.992.1 (ADSL) Annex A

I think the 887VA treats the VDSL as an additional interface - called Ethernet0 (not FastEthernet0)

The config we use in the UK is below - but you have to shutdown the ATM interface, enable the Ethernet0 and set the correct VLAN on the outside

controller VDSL 0
interface ATM0
no ip address
shutdown
no atm ilmi-keepalive

interface Ethernet0
no ip address
no shutdown

interface Ethernet0.101
encapsulation dot1Q 101
pppoe enable group global
pppoe-client dial-pool-number 1

Bear in mind that if you shutdown the ATM interface you'll lose remote connectivity to the device...

I've attached a redacted FTTC config that we know works here in the UK

igotafix1 · ‎11-18-2015

Thanks parkbenchit... I am not trying to do VDSL. My line only has ADSL or perhaps ADSL2.

In any case, the 887 is not performing well at all on the DSL front.

I will follow up on the MTU/MSS suggestion when I can work out how to chagne the MTU on interface vi2.

I also noticed this in the log, so i may try and increase that threshold, but that shouldn't be causing such severe degradtion:

Nov 18 10:08:28.995: %IP_VFR-4-FRAG_TABLE_OVERFLOW: Dialer0: the fragment table has reached its maximum threshold 16

Any idea how I can get VDSL controller firmware legitimately?

parkbenchit · ‎11-19-2015

Ok

By the looks of it, the fact that it's doing

Trained Mode: G.992.1 (ADSL) Annex A

is basic ADSL

https://en.wikipedia.org/wiki/G.992.1

I would suggest finding out what the ADSL mode is when you're getting 12Mb from the other device, as my feeling is that the Huawei and the Cisco are not doing the same ADSL mode.

I'd also suggest resolving the MTU issue. Running something like this

ping 8.8.8.8 repeat 100 size 1492

and changing the size will help you locate an MTU that works properly.

Firmware: If your router is covered by SmartNet - then you'll be able to get updates. But I would focus my efforts on getting the MTU right and checking the ADSL mode before doing this - it's much, much more likely to be a configuration issue rather than a firmware problem

These links might be helpful

http://wiki.mundy.co/Upgrading_IOS_on_Cisco

http://www.alcatron.net/?p=55 (towards the bottom, but several years old)

Either way, the best way to ensure you get the correct & up to date firmware is to register with Cisco

https://tools.cisco.com/IDREG/guestRegistration.do

Fragment table: I think this is just the IP virtual reassembly and something to be expected, esp with an MTU / MSS probably with issues at the moment.