Cisco 877 not getting full ADSL speed?

Discussion in 'Routing & Switching' started by phatboy, Jan 11, 2011.

  1. phatboy

    phatboy Nibble Poster

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    Hi everyone, thanks for all the input! I have now got to the root of the problem! :) But could still use a little help!

    The issue is with the BVI interface

    When I do not have a bridge interface assigned, and am using a cable connection in VLAN 2, with Interface VLAN 2 set up as the NAT inside interface, I get 13.5mb throughput.

    However as soon as I move the IP address and NAT statments to the BVI interface and add the VLAN interface to the bridge group, the speedtest result is reduced to 9.5mb. This speed is the same on the LAN and WLAN connections.

    The question is... why?! Is the router maybe not capable of converting over the bridge at the speed I need?

    I'm pleased to have identified the cause of this :)

    And for info, I also set up an 877 router at work thats not wireless and it achieves 17mb downstream, so that proves these routers are capable :D

    Cheers
    Tim
     
    Certifications: CCNA R&S, CCNA Security, CCNA Voice, CCA 5.0, MCP 70-290 70-270 70-431
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  2. BosonMichael
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    BosonMichael Yottabyte Poster

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    Good work, Tim! :)
     
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  3. phatboy

    phatboy Nibble Poster

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    Hi all,

    Well I reconfigured the router, so that I had a differnet VLAN on the LAN and WLAN. I scrapped the BVI interfaces, and instead gave the dot11 sub-interface an IP address, and made it a IP NAT inside interface. I did the same with the LAN VLAN interface

    And I thought this was the end of it, but... sadly not!

    Now if I run a speedtest using a cable onto the LAN VLAN, I get 13.8mb in Speedtests - NICE!

    But from the wireless, I STILL only get 9.5mb :( :(

    I am stumped once again. The CPU utilisation is still quite high (95%) during a Speedtest, if thats an indicator?

    Thanks
    Tim
     
    Certifications: CCNA R&S, CCNA Security, CCNA Voice, CCA 5.0, MCP 70-290 70-270 70-431
    WIP: CCNP R&S, CCNA Wireless
  4. BosonMichael
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    BosonMichael Yottabyte Poster

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    The CPU's gotta decrypt those wireless packets as they come in. I'm guessing that's at least part of the issue.
     
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  5. phatboy

    phatboy Nibble Poster

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    This is true, however I turned off all encryption and the results were the same :(
     
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  6. BosonMichael
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    Is the channel clean? If not, the router is having to listen to traffic from all those other sources that are broadcasting on that channel.

    Plus, how many devices do you have on your network associating with the router? They generate traffic as well... all things to consider in a wireless environment.
     
    Certifications: CISSP, MCSE+I, MCSE: Security, MCSE: Messaging, MCDST, MCDBA, MCTS, OCP, CCNP, CCDP, CCNA Security, CCNA Voice, CNE, SCSA, Security+, Linux+, Server+, Network+, A+
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  7. ThomasMc

    ThomasMc Gigabyte Poster

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    Haha is this how the CCNAs roll :twisted:
     
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  8. phatboy

    phatboy Nibble Poster

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    I am not totally sure how to get the router to choose a clean channel.... When I turn on the Dot11 interface it says its scanning for a suitable frequency, is this looking for the cleanest one?

    I have been testing with just 1 device associated

    What do you mean? Are you implying I should know this because I have sat a CCNA?
     
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  9. BosonMichael
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    I am not certain, but I am fairly sure that you can statically assign the channel that it uses.

    In any case, you'd have to sniff to see how congested the other channels are. I've used Netstumbler in the past.
     
    Last edited: Jan 24, 2011
    Certifications: CISSP, MCSE+I, MCSE: Security, MCSE: Messaging, MCDST, MCDBA, MCTS, OCP, CCNP, CCDP, CCNA Security, CCNA Voice, CNE, SCSA, Security+, Linux+, Server+, Network+, A+
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  10. ThomasMc

    ThomasMc Gigabyte Poster

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  11. Spice_Weasel

    Spice_Weasel Kilobyte Poster

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    Something to check - you mention cpu usage is 95%, but what process is responsible?

    Use "sh proc cpu sort 5sec" and see what process is eating up cpu time.

    Also, you can use "sh dot11 int" to see statistics, in particular look at the last 5 seconds data, while testing transfer rates. Clear the stats just before a test to get a good picture as well.


    Spice Weasel
     
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  12. Mack

    Mack New Member

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    having seen the 12Mbps throughput limitation on a few sites, I just thought i'd comment that the 877 is capable of more than that
    Code:
                     DS Channel1      DS Channel0   US Channel1       US Channel0
    Speed (kbps):             0            19043             0              1023
    Cells:                    0        225694765             0         513143799
    Reed-Solomon EC:          0             5898             0                 0
    CRC Errors:               0             1804             0                 0
    Header Errors:            0             1654             0                 0
    Total BER:                0E-0           1235E-8
    Leakage Average BER:      0E-0           7458E-10
    Interleave Delay:         0               23             0                 0
    Have been downloading a 10gb file, and getting sustained 15MBps, CPU is showing

    Code:
    CPU utilization for five seconds: 69%/66%; one minute: 63%; five minutes: 63%
    [​IMG]

    And just some of the other stats for completeness really

    Code:
    Alcatel 20190 chipset information
                    ATU-R (DS)                      ATU-C (US)
    Modem Status:    Showtime (DMTDSL_SHOWTIME)
    DSL Mode:        ITU G.992.5 (ADSL2+) Annex A
    ITU STD NUM:     0x03                            0x2 
    Chip Vendor ID:  'STMI'                          'GSPN'
    Chip Vendor Specific:  0x0000                    0x0010
    Chip Vendor Country:   0x0F                      0xFF
    Modem Vendor ID: 'CSCO'                          'GSPN'
    Modem Vendor Specific: 0x0000                    0x1000
    Modem Vendor Country:  0xB5                      0xFF
    Serial Number Near:    FHK13012268
    Serial Number Far:     
    Modem VerChip ID:        C196 (0)
    DFE BOM:         DFE3.0 Annex A (1)
    Capacity Used:   99%                             100%
    Noise Margin:     5.5 dB                         12.0 dB
    Output Power:    20.0 dBm                        12.5 dBm
    Attenuation:     23.0 dB                          8.0 dB
    Defect Status:   None                            None                        
    Last Fail Code:  None
    Watchdog Counter: 0xE9
    Watchdog Resets: 0
    Selftest Result: 0x00
    Subfunction:     0x00 
    Interrupts:      8289 (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
     
  13. Gav

    Gav Kilobyte Poster

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    Sorry to bump a semi-old thread, but is the conclusion here that the 877w can support the higher speeds of ADSL2+?

    I saw ADSL2+ and Cisco and just sort of presumed it would...

    My Thomson router from O2 is currently synced at 14,405/1,325 (it's normally a bit higher, but the router is slowly dying, hence the replacement), and the throughput is usually very near the sync speed. I'm only planning to use it at home with no more than three users connected at once, but it'd still be nice to get the speeds I pay for!
     
  14. Bluerinse
    Honorary Member

    Bluerinse Exabyte Poster

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    ADSL 2+ is still very much dependant on the distance you are from your exchange and more specifically your ISP's DSLAMS. Contact your ISP if you think your not getting the speeds you should, there are many tweaks that could improve things for you.
     
    Certifications: C&G Electronics - MCSA (W2K) MCSE (W2K)
  15. phatboy

    phatboy Nibble Poster

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    Sorry for not responding to my own thread.

    In the end I gave up. The Cisco 877 is definitely capable of up to 22mb (I've set up a few recently on 20mb circuits). It suffers with the wireless part - for some reason the wireless cannot get the speed.

    If you are using a Ethernet cable you will get the speed.

    So maybe you need a Cisco 877 (non wireless), and another brand wireless AP?

    Tim
     
    Certifications: CCNA R&S, CCNA Security, CCNA Voice, CCA 5.0, MCP 70-290 70-270 70-431
    WIP: CCNP R&S, CCNA Wireless
  16. Gav

    Gav Kilobyte Poster

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    Sorry, what I meant was, I get ~15Mbps on my Thomson box, would I get that on a Cisco 877w or is it limited to 12Mbps?

    I'm quite happy with the speed that I'm getting at the moment, but the router needs replacing. I just wanted to make sure that the Cisco 877w wouldn't have any sort of bottleneck, and that I'll get the maximum speed my line supports.
     
  17. phatboy

    phatboy Nibble Poster

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    I would say you will get the full 15mpbs, but only about 10 will get to your machine over wifi. Any cabled connection will get the full 15
     
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  18. Gav

    Gav Kilobyte Poster

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    Just saw this, perfect.

    The house is wired with Cat5e anyway, and there are two additional access points (lead lined chimneys + Victorian walls = wifi fail) in the house, so as long as the wired throughput is good, I'm happy.

    It's just a shame Cisco don't do any integrated services routers with built in gigabit switches. I might even end up going for a Linksys/Billion.
     
  19. BosonMichael
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    BosonMichael Yottabyte Poster

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    That's the nature of wireless... encryption and CSMA/CA will lower the amount of throughput you're gonna get.
     
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  20. phatboy

    phatboy Nibble Poster

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    Although my Netgear router manages it without any hassle!!
     
    Certifications: CCNA R&S, CCNA Security, CCNA Voice, CCA 5.0, MCP 70-290 70-270 70-431
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