[c-nsp] PPP Mulitilink on 3620

[David Simmons - EliteUKServe.Net]

Hi Rodney,

I have turned off the PPP fragmentation. CPU usage this morning is circa 
40% ... however traffic is only about 1-2MB through this link so far.

I will see what happens later on when things get busy. 

Cheers,

Dave


On Tuesday 22 February 2005 22:30, Rodney Dunn wrote:
> 4 T1's in a bundle is probably pushing the CPH
> hp of a 3620.
>
> Try turning off PPP fragmentation since you
> are not doing QOS and see how much CPU
> overhead you get back.
>
> We've had this discussion before on this alias
> how in theory you do get a slightly longer latency
> over a bundle if you do this in theory but
> very few times is it a difference at the T1 rate
> that people notice.
>
> Rodney
>
> On Tue, Feb 22, 2005 at 03:43:58PM +0000, David Simmons - EliteUKServe.Net
>
> wrote:
> > Hi,
> >
> > We have a link for a service provider and they insisted on shoving in a
> > fibre to our building then splitting the fibre into 4 x 2mb tribs. Then
> > from there we have 4 x X25 into a 3620 with a NM-4T. Now our other
> > providers give us LES circuits etc.. We run BGP.
> >
> > It has all worked fine untill the traffic started rising to say nearly
> > 4MB on this line. Then the CPU usage goes bananas on this router. Packets
> > start being lost and we get very high ping times. All this router does is
> > the PPP multilink and is then directly connect to a 7200 ... which
> > handles the BGP etc.
> >
> > My question is ... and I will admit to not being extremely cisco
> > knowledgable (this was dumped on my desk) ... is is this simply a matter
> > of the router not being able to handle whats chucked at it ... or could
> > there be things we are doing or not doing right with the multilink?
> >
> > Hoping you may have some ideas.
> >
> > Regards,
> >
> > David SImmons
> >
> > interface Multilink1
> >  description ### Multilink (4 Serials) ###
> >  bandwidth 8192
> >  ip address xx.xx.xx.xx 255.255.255.252
> >  ip access-group 151 in
> >  ip access-group 101 out
> >  ppp multilink
> >  multilink-group 1
> >
> > [cut]
> >
> > interface Serial1/0
> >  description ### Trib 1 ###
> >  bandwidth 2048
> >  no ip address
> >  no ip proxy-arp
> >  encapsulation ppp
> >  no ip mroute-cache
> >  serial restart-delay 0
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial1/1
> >  description ### Trib 2 ###
> >  bandwidth 2048
> >  no ip address
> >  no ip proxy-arp
> >  encapsulation ppp
> >  no ip mroute-cache
> >  serial restart-delay 0
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial1/2
> >  description ### Trib 3 ###
> >  bandwidth 2048
> >  no ip address
> >  no ip proxy-arp
> >  encapsulation ppp
> >  no ip mroute-cache
> >  serial restart-delay 0
> >  ppp multilink
> >  multilink-group 1
> > !
> > interface Serial1/3
> >  description ### Trib 4 ###
> >  bandwidth 2048
> >  no ip address
> >  no ip proxy-arp
> >  encapsulation ppp
> >  no ip mroute-cache
> >  serial restart-delay 0
> >  ppp multilink
> >  multilink-group 1
> >
> > [cut]
> >
> > ip classless
> > ip route 0.0.0.0 0.0.0.0 Multilink1
> > ip route xx.xx.xx.0 255.255.240.0 xx.xx.xx.26
> > ip route xx.xx.xx.1 255.255.255.255 xx.xx.xx.26
> >
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