[cisco-nas] Multilink PPP issue

[lee.e.rian at census.gov]

If I was determined to make multilink PPP work over different speed links 
the first thing I'd try is disabling fragmentation - eg

interface Multilink1
 ppp multilink
 ppp multilink group 1
 ppp multilink fragment disable

but my only experience with multilink ppp is bundling T1s together between 
routers, so the suggestion might very well be worth exactly what you paid 
for it :)

Regards,
Lee





From:   "JoeMays" <jfmays at launchpad.win.net>
To:     <cisco-nas at puck.nether.net>
Date:   05/04/2011 05:30 PM
Subject:        [cisco-nas] Multilink PPP issue
Sent by:        cisco-nas-bounces at puck.nether.net



Trying to bond together two pppoe links into one multilink bundle. The 
links admittedly are not the same speed, one goes through a DSL modem 
bridged ethernet connection that has two bonded DSL lines, the other goes 
through a single-DSL line bridged modem.
 
The links bundle alright, but the performance sucks. Console output on the 
router whenever a significant amount of data is being downloaded shows....
 
4d23h: Vi2 MLP: Lost fragment 7641 (all links out of sequence)
4d23h: Vi2 MLP: Begin bit lost, discard fragment 7642
4d23h: Vi2 MLP: Lost fragment 7697 (all links out of sequence)
4d23h: Vi2 MLP: Discard reassembled packet
4d23h: Vi2 MLP: Lost fragment 76BD (all links out of sequence)
4d23h: Vi2 MLP: Discard reassembled packet
4d23h: Vi2 MLP: Lost fragment 76D9 (all links out of sequence)
4d23h: Vi2 MLP: Discard reassembled packet
4d23h: Vi2 MLP: Lost fragment 76E5 (all links out of sequence)
4d23h: Vi2 MLP: Discard reassembled packet
4d23h: Vi2 MLP: Lost fragment 7751 (all links out of sequence)
4d23h: Vi2 MLP: Discard reassembled packet
4d23h: Vi2 MLP: Lost fragment 775B (all links out of sequence)
4d23h: Vi2 MLP: Discard reassembled packet
 
... and so on. These messages don’t occur if I only have one link in the 
bundle, and each link performs at the speed it should by itself. The 
errors only occur when both links are in the bundle, and then the speed is 
also at the floor. Is this because of the fact that two different link 
speeds are at work? Or could there be another cause in the mlppp config? 
Is there a way to weigh the links so that the bonded dual line DSL link 
carries twice the traffic of the single line DSL link?
 
Joe Mays
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