[c-nsp] Multilink PPP throughput instable

[tony kam]

Thanks Mikael! If it is still getting the same result after all these TCP 
optimization, do you think there is something to do with MLPPP 
configurations? Or it is the behavior of MLPPP bundle under heavy 
congestion?
Please note that individual E1 link is working perfect in bidirectional ftp, 
i.e., put and get at the same time on the same pair of servers.



----- Original Message ----- 
From: "Mikael Abrahamsson" <swmike at swm.pp.se>
To: <cisco-nsp at puck.nether.net>
Sent: Sunday, April 24, 2005 8:44 PM
Subject: Re: [c-nsp] Multilink PPP throughput instable


> On Sun, 24 Apr 2005, tony kam wrote:
>
>> Any idea why it can't get stable throughput in mixed direction?
>
> My guess would be that the ACKs being delayed means you will get TCP
> stalls. You should check the window sizes on each side so they're
> sufficiently high (512kilobyte and window scaling on (mostly a problem on
> Windows machines).
>
> If you're running windows, "tcp optimizer" is a good program, can be found
> on <http://www.speedguide.net/downloads.php>.
>
> -- 
> Mikael Abrahamsson    email: swmike at swm.pp.se
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/
>

Hello,

The topology is:

1. 2610XM connects to 2650XM with 2xE1 links with PPP multilink.
2. Same 2650XM connects with another 2610XM with another pair of E1 links.

Results:
1. Single FTP session in either direction can pump the bundle to a stable 
throughput around 3.9M.
2. Dual FTP sessions in mixed direction (put and get together) can only get 
a variable throughput from 3.1M to 3.9M.

All routers CPU are below 30%.

Any idea why it can't get stable throughput in mixed direction?
Is it due to MLPPP overhead?
Is "no ppp multilink fragmentation" helpful in this case?

Thanks,
Tony



Below is the extract of the config.

2610XM (both the same)
----------------------
interface Multilink1
 ip address 15.63.232.1 255.255.255.252
 load-interval 30
 no cdp enable
 ppp multilink
 ppp multilink group 1
!
interface Serial0/0
 bandwidth 1984
 no ip address
 no ip redirects
 no ip proxy-arp
 encapsulation ppp
 load-interval 30
 no fair-queue
 no cdp enable
 ppp multilink
 ppp multilink group 1
!
interface Serial0/1
 bandwidth 1984
 no ip address
 no ip redirects
 no ip proxy-arp
 encapsulation ppp
 load-interval 30
 no fair-queue
 no cdp enable
 ppp multilink
 ppp multilink group 1
!

2650XM
------
interface Multilink1
 ip address 15.63.231.2 255.255.255.252
 load-interval 30
 ppp multilink
 ppp multilink group 1
!
interface Multilink2
 ip address 15.63.232.2 255.255.255.252
 load-interval 30
 ppp multilink
 ppp multilink group 2
!
interface Serial0/0:0
 bandwidth 1984
 no ip address
 encapsulation ppp
 load-interval 30
 no fair-queue
 ppp multilink
 ppp multilink group 1
!
interface Serial0/1:0
 bandwidth 1984
 no ip address
 encapsulation ppp
 load-interval 30
 no fair-queue
 ppp multilink
 ppp multilink group 1
!
interface Serial1/0:0
 no ip address
 encapsulation ppp
 no fair-queue
 ppp multilink
 ppp multilink group 2
!
interface Serial1/1:0
 no ip address
 encapsulation ppp
 no fair-queue
 ppp multilink
 ppp multilink group 2
!





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