[c-nsp] PPP Mulitilink on 3620

[Rodney Dunn]

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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