CfgReject MRU - PPP

This is a discussion on CfgReject MRU - PPP ; What's the groups thoughts about this LCP negotiation. The local wants MRU 1400 and the remote is insisting on 1500. Oddly enough, when the remote finally sends CfgReject instead of CfgNak, the local apparently tosses it's config and settles for ...

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Thread: CfgReject MRU

  1. CfgReject MRU

    What's the groups thoughts about this LCP negotiation. The local wants MRU
    1400 and the remote is insisting on 1500. Oddly enough, when the remote
    finally sends CfgReject instead of CfgNak, the local apparently tosses it's
    config and settles for default 1500.

    12:29:58.925 === LCP ENTERING ESTABLISH PHASE
    12:29:58.926 ==> LCP/REQSENT CfgReq/0x01 id 0xD9 len 14 F945636A>
    12:29:58.937 <== LCP/REQSENT CfgReq/0x01 id 0x01 len 15 MD-5>
    12:29:58.938 ==> LCP/REQSENT CfgAck/0x02 id 0x01 len 15 MD-5>
    12:29:58.947 <== LCP/ACKSENT CfgNak/0x03 id 0xD9 len 8
    12:29:58.948 ==> LCP/ACKSENT CfgReq/0x01 id 0xDA len 14 F945636A>
    12:29:59.026 <== LCP/ACKSENT CfgNak/0x03 id 0xDA len 8
    12:29:59.026 ==> LCP/ACKSENT CfgReq/0x01 id 0xDB len 14 F945636A>
    12:29:59.070 <== LCP/ACKSENT CfgNak/0x03 id 0xDB len 8
    12:29:59.075 ==> LCP/ACKSENT CfgReq/0x01 id 0xDC len 14 F945636A>
    12:29:59.079 <== LCP/ACKSENT CfgNak/0x03 id 0xDC len 8
    12:29:59.080 ==> LCP/ACKSENT CfgReq/0x01 id 0xDD len 14 F945636A>
    12:29:59.100 <== LCP/ACKSENT CfgNak/0x03 id 0xDD len 8
    12:29:59.111 ==> LCP/ACKSENT CfgReq/0x01 id 0xDE len 14 F945636A>
    12:29:59.138 <== LCP/ACKSENT CfgReject/0x04 id 0xDE len 8
    12:29:59.139 ==> LCP/ACKSENT CfgReq/0x01 id 0xDF len 10
    12:29:59.143 <== LCP/ACKSENT CfgAck/0x02 id 0xDF len 10
    ....



  2. Re: CfgReject MRU

    "Bob Cernohous" writes:
    > What's the groups thoughts about this LCP negotiation. The local wants MRU
    > 1400 and the remote is insisting on 1500. Oddly enough, when the remote
    > finally sends CfgReject instead of CfgNak, the local apparently tosses it's
    > config and settles for default 1500.


    Sending an LCP Configure-Nak with MRU set to 1500 is pretty silly.
    You can get the same effect with less trouble by sending
    Configure-Reject instead. Plus, refusing to listen to the peer's
    request for a different MRU is mildly silly, but might be meaningful
    in some contexts (as with demand dial and an interface that cannot
    have its MRU/MTU changed midstream).

    Other than that, I don't see anything wrong with the trace you've
    posted. Implementations are *required* to stop sending an option once
    Configure-Reject is received. The only choices at that point are to
    give up (and shut the link down) or give up (and accept that you must
    use the default).

    --
    James Carlson, IP Systems Group
    Sun Microsystems / 1 Network Drive 71.234W Vox +1 781 442 2084
    MS UBUR02-212 / Burlington MA 01803-2757 42.497N Fax +1 781 442 1677

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