Re: IEWB Lab1 4.7 ppp multilink posted 08/11/2004
I stand corrected. Thank you Scott Morris.
This is why Group Study is so great.
I'm always learning something new.
----- Original Message -----
From: "Scott Morris" <swm@xxxxxxxxxx>
To: "'ccie2be'" <ccie2be@xxxxxxxxxx>; "'Carlos G Mendioroz'"
<tron@xxxxxxxxxxx>; "'Group Study'" <ccielab@xxxxxxxxxxxxxx>
Sent: Wednesday, August 11, 2004 8:03 AM
Subject: RE: IEWB Lab1 4.7 ppp multilink
> I think the confusion comes with some of Cisco's descriptions. See
> The basic description is that LFI is responsible to sequence and
> packets properly when balancing over multiple links (implying, of course,
> that more than one link is necessary).
> If you look a little further down though, you do see the
> exception/restriction which falls into the specific category you are
> about! "Interleaving on MLP allows large packets to be multilink
> encapsulated and fragmented into a small enough size to satisfy the delay
> requirements of real-time traffic; small real-time packets are not
> multilink encapsulated and are sent between fragments of the large
> Interestingly enough, none of the examples shown make any requirement for
> minimum links, which carries the logic that interleaving and fragmentation
> will work just as well with only one particular link coming up, because
> 'ppp multilink' is used, you can still have a a bundle of one.
> Another good document to view (also containing the table of fragmentation
> recommendations that I used to have and 'lost'!!!) is
> 094660.shtml which shows this using a multilink interface although it is
> only applied to a single interface (hence bundle of 1).
> Scott Morris, CCIE4 (R&S/ISP-Dial/Security/Service Provider) #4713, CISSP,
> JNCIP, et al.
> IPExpert CCIE Program Manager
> IPExpert Sr. Technical Instructor
> -----Original Message-----
> From: nobody@xxxxxxxxxxxxxx [mailto:nobody@xxxxxxxxxxxxxx] On Behalf Of
> Sent: Wednesday, August 11, 2004 7:20 AM
> To: Carlos G Mendioroz; Group Study
> Subject: Re: IEWB Lab1 4.7 ppp multilink
> I have to disagree with you on this.
> If only one bri is used, how can multilink fragment and interleave over
> multple paths?
> For fragmentation to take place, there needs to be at least 2 paths over
> which traffic is sent.
> I think where you're getting confused is with the command, ppp multilink.
> True, this command is required before ppp will fragment packets, but by
> itself, it's not sufficient. There also has to be multiple paths over
> to send traffic.
> That's where the 2nd command comes into play. By adding the command, ppp
> multilink links min 2, you're insuring that there will always be 2 bri's.
> Now, the ppp multilink command can actually fragment packets and split the
> fragments across the 2 bri's.
> HTH, Tim
> ----- Original Message -----
> From: "Carlos G Mendioroz" <tron@xxxxxxxxxxx>
> To: "Group Study" <ccielab@xxxxxxxxxxxxxx>
> Sent: Wednesday, August 11, 2004 5:37 AM
> Subject: IEWB Lab1 4.7 ppp multilink
> > Requirement is to have LFI (Link Fragmentation and interleaving)
> > no matter what load on the first channel.
> > Proposed answer is to have multilink with minimum 2.
> > From where should I get the info that I have to dial with two channels
> > ? LFI is up as soon as I do multilink AFAIK, so 4.7 does not imply load
> > threshold... so for me ppp multilink would be enough.
> > This is where one gets very picky as to doing the thing they want you to
> > do and not what they ask you to do...
> > Or am I missing something ?
> > --
> > Carlos G Mendioroz <tron@xxxxxxxxxxx> LW7 EQI Argentina
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