Multilink PPP between Linux and Cisco - anybody?

Discussion in 'Cisco' started by John Hardin, Nov 8, 2004.

  1. John Hardin

    John Hardin Guest

    All:

    I am attempting to configure multiple T1s between a Redhat Linux 9.0 box
    and a Cisco router, using multilink PPP.

    I am running into two problems which together are showstoppers.

    1) Every five minutes or so (the time varies) the Cisco sends a LCP config
    request, which renegotiates the PPP session. There is no apparent reason
    for it to do this.

    2) With multilink enabled, this kills the PPP daemon.

    I have worked around it with scripting so that everything recovers
    automatically, but the downtime eats a significant percentage of the
    bandwidth and will not be acceptable in production. Even if the pppd were
    not dying, I would think the amount of reconfiguration (and related
    downtime) to be excessive. Unless I can correct these problems this
    project will fail.

    Has ANYONE EVER gotten multilink PPP over T1s from Linux to Cisco
    equipment working reliably?

    Is ANYONE using multilink PPP from Linux to Cisco equipment over any kind
    of physical layer?

    Does anyone know why the Cisco is renegotiating so often, and how to
    configure it to not do so?

    Assistance fairly desperately sought - thanks for any responses.

    Specs:

    Redhat Linux 9.0
    2.4.20-31.9smp kernel from the fedoralegacy site
    ppp-2.4.1-10
    Sangoma Wanpipe S514-7-PCI dual T1/E1 card
    WANPIPE Hardware Support Module Stable 2.3.1-2

    http://bugzilla.fedora.us/show_bug.cgi?id=2229

    --
    John Hardin
    Internal Systems Administrator (Seattle)
    CRS Retail Systems, Inc.
    3400 188th Street SW, Suite 185
    Lynnwood, WA 98037
    voice: (425) 672-1304
    fax: (425) 672-0192
    email:
    web: http://www.crsretail.com
    -----------------------------------------------------------------------
    If you smash a computer to bits with a mallet, that appears to count
    as encryption in the state of Nevada.
    - CRYPTO-GRAM 12/2001
    -----------------------------------------------------------------------
     
    John Hardin, Nov 8, 2004
    #1
    1. Advertising

  2. John Hardin

    John Hardin Guest

    On Mon, 08 Nov 2004 20:35:12 +0000, John Hardin wrote:

    > 1) Every five minutes or so (the time varies) the Cisco sends a LCP
    > config request, which renegotiates the PPP session. There is no apparent
    > reason for it to do this.


    I ran an analysis and the duration is pretty reliably 140 seconds from the
    end of the initial LCP configuration. I guess that shows how accurate my
    cuffs are... :)

    I believe I understand what is going on now, and it looks to me like a bug
    in the Cisco PPP implementation.

    The Linux pppd was sending LCP ConfReqs as soon as the T1 came up. The
    Cisco was ignoring them (neither ACKing nor NAKing), but apparently was
    remembering them. After the LCP and IPCP configuration completed and 140
    seconds passed, the Cisco would start a renegotiation and AT THAT TIME it
    would ACK the ConfReqs from the ORIGINAL negotiation. I assume it
    remembered that it had received them, and after some internal timer
    expired, would see them and decide the link was in a down state and needed
    to be reconfigured.

    Workaround: set my ppp options to:
    lcp-restart 45
    lcp-max-configure 2
    ....which essentially makes the Linux pppd passive. It doesn't send any LCP
    confreqs that the Cisco can see (the first gets lost during T1 setup) and
    thus it doesn't remember them and get confused about the link state.

    My Multilink PPP T1 configuration using the Sangoma Wanpipe Dual T1 card
    to a Cisco router at Sprint is UP and appears reliable with this change.
    This hardware is RECOMMENDED. Please note: make sure you get the latest
    stable Wanpipe drivers if you want to do this. They had to make some
    changes to get this up and running here. A gold star for Nenad Corbic
    at Sangoma!

    Here are the details:

    =================================
    Nov 10 08:08:18 t1_up: Starting pppd on wanpipe1...
    Nov 10 08:08:19 wanpipe1_pppd: using channel 1
    Nov 10 08:08:19 wanpipe1_pppd: Connect: <--> /dev/ttyWP0
    Nov 10 08:08:19 wanpipe1_pppd: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....T1 in YEL alarm, no PPP responses (not too surprising)
    ....note our magic: 0x22d00757
    ....T1 takes 20 sec to come up

    Nov 10 08:08:40 wanpipe1_pppd: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....OK, T1 now up

    Nov 10 08:08:41 wanpipe1_pppd: rcvd [LCP ConfReq id=0x5c <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    ....First confreq from Cisco router

    Nov 10 08:08:41 wanpipe1_pppd: sent [LCP ConfAck id=0x5c <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    ....We ACK it

    Nov 10 08:08:43 wanpipe1_pppd: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....and send a REQ of our own

    Nov 10 08:08:43 wanpipe1_pppd: rcvd [LCP ConfReq id=0x5d <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:08:43 wanpipe1_pppd: sent [LCP ConfAck id=0x5d <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:08:45 wanpipe1_pppd: rcvd [LCP ConfReq id=0x5e <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:08:45 wanpipe1_pppd: sent [LCP ConfAck id=0x5e <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:08:46 wanpipe1_pppd: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    Nov 10 08:08:47 wanpipe1_pppd: rcvd [LCP ConfReq id=0x5f <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:08:47 wanpipe1_pppd: sent [LCP ConfAck id=0x5f <magic 0x17de7f4> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    ....chat chat chat
    ....To this point we have received NO ConfAcks for ANY of the ConfReqs we have sent...

    Nov 10 08:08:49 wanpipe1_pppd: sent [LCP ConfReq id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    Nov 10 08:08:49 wanpipe1_pppd: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....Finally, one gets ACKed!

    Nov 10 08:08:49 wanpipe1_pppd: Using interface ppp0
    Nov 10 08:08:49 wanpipe1_pppd: New bundle ppp0 created
    Nov 10 08:08:49 wanpipe1_pppd: sent [IPCP ConfReq id=0x1 <addr x.x.x.x>]
    Nov 10 08:08:51 wanpipe1_pppd: rcvd [IPCP ConfReq id=0xd9 <addr x.x.x.x>]
    Nov 10 08:08:51 wanpipe1_pppd: sent [IPCP ConfAck id=0xd9 <addr x.x.x.x>]
    Nov 10 08:08:52 wanpipe1_pppd: sent [IPCP ConfReq id=0x1 <addr x.x.x.x>]
    Nov 10 08:08:52 wanpipe1_pppd: rcvd [IPCP ConfAck id=0x1 <addr x.x.x.x>]
    Nov 10 08:08:52 wanpipe1_pppd: local IP address x.x.x.x
    Nov 10 08:08:52 wanpipe1_pppd: remote IP address x.x.x.x
    ....Okay, everything is up and running

    Nov 10 08:08:52 wanpipe1_pppd: Script /etc/ppp/ip-up started (pid 4478)
    Nov 10 08:08:53 wanpipe1_pppd: Script /etc/ppp/ip-up finished (pid 4478), status = 0x0
    ....everything is fine for a while, then...

    Nov 10 08:11:09 wanpipe1_pppd: rcvd [LCP ConfReq id=0x60 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    ....Cisco wants to reconfigure! Note the magic has changed...

    Nov 10 08:11:09 wanpipe1_pppd: Script /etc/ppp/ip-down started (pid 5628)
    ....Okay, tearing down our end

    Nov 10 08:11:09 wanpipe1_pppd: sent [LCP ConfReq id=0x2 <asyncmap 0x0> <magic 0xcaee1de0> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....Here we send a ConfReq of our own with a new magic: 0xcaee1de0

    Nov 10 08:11:09 wanpipe1_pppd: sent [LCP ConfAck id=0x60 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    ....We ACK the Cisco's reconfigure REQ

    Nov 10 08:11:09 wanpipe1_pppd: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    Nov 10 08:11:09 wanpipe1_pppd: rcvd [LCP ConfAck id=0x1 <asyncmap 0x0> <magic 0x22d00757> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....Huh? We just received two ACKs for requests we sent minutes ago!
    ....Note the OLD magic number...

    Nov 10 08:11:11 wanpipe1_pppd: rcvd [LCP ConfReq id=0x61 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:11:11 wanpipe1_pppd: sent [LCP ConfAck id=0x61 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:11:12 wanpipe1_pppd: sent [LCP ConfReq id=0x2 <asyncmap 0x0> <magic 0xcaee1de0> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    Nov 10 08:11:13 wanpipe1_pppd: rcvd [LCP ConfReq id=0x62 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:11:13 wanpipe1_pppd: sent [LCP ConfAck id=0x62 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:11:14 wanpipe1_pppd: Script /etc/ppp/ip-down finished (pid 5628), status = 0x0
    Nov 10 08:11:15 wanpipe1_pppd: rcvd [LCP ConfReq id=0x63 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:11:15 wanpipe1_pppd: sent [LCP ConfAck id=0x63 <magic 0x180313d> <mrru 1500> <endpoint [local:73.6c.2d.67.77.35.2d.74.61.63]>]
    Nov 10 08:11:15 wanpipe1_pppd: sent [LCP ConfReq id=0x2 <asyncmap 0x0> <magic 0xcaee1de0> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    Nov 10 08:11:15 wanpipe1_pppd: rcvd [LCP ConfAck id=0x2 <asyncmap 0x0> <magic 0xcaee1de0> <mrru 1500> <endpoint [MAC:00:02:a5:8a:35:64]>]
    ....and so forth.
    =================================

    --
    John Hardin
    Internal Systems Administrator (Seattle)
    CRS Retail Systems, Inc.
    3400 188th Street SW, Suite 185
    Lynnwood, WA 98037
    voice: (425) 672-1304
    fax: (425) 672-0192
    email:
    web: http://www.crsretail.com
    -----------------------------------------------------------------------
    If you smash a computer to bits with a mallet, that appears to count
    as encryption in the state of Nevada.
    - CRYPTO-GRAM 12/2001
    -----------------------------------------------------------------------
     
    John Hardin, Nov 10, 2004
    #2
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Burticio
    Replies:
    0
    Views:
    917
    Burticio
    Jan 30, 2004
  2. Diego Balgera

    Ppp multilink with Cisco 760

    Diego Balgera, Feb 23, 2004, in forum: Cisco
    Replies:
    1
    Views:
    595
    Aaron Leonard
    Feb 23, 2004
  3. Karnov
    Replies:
    1
    Views:
    8,716
    CCIE8122
    May 24, 2004
  4. Andrew Gideon
    Replies:
    5
    Views:
    5,471
  5. DoubleD4

    Cisco Multilink PPP Issue

    DoubleD4, Apr 13, 2006, in forum: Cisco
    Replies:
    10
    Views:
    27,190
    DoubleD4
    Apr 15, 2006
Loading...

Share This Page