[c-nsp] ip cef load sharing

[Ben Steele]

Dan the reason your having issues is not MTU related, it's NAT related, 
because you have 3 ADSL lines each doing NAT against a different outside IP 
when you turn on per-packet load sharing you end up with flows to the same 
destination having different source IP addresses.

Your only option is per-destination load balancing (ie the default), one way 
you can tweak this a little without breaking to much is to change the 
standard algorithm to include ports.

Try adding "ip cef load-sharing algorithm include-ports destination" into 
your global config once you've removed your per-packet load sharing and see 
how you go.

You are never going to get perfect load balancing in your scenario but if 
you have enough hosts on your LAN it should be sufficient enough, one way 
you can do per-packet is if you get another IP routed down all 3 adsl lines 
and put it on a loopback and NAT everything against that.

Ben

----- Original Message ----- 
From: "Dan Letkeman" <danletkeman at gmail.com>
To: "Rodney Dunn" <rodunn at cisco.com>; <cisco-nsp at puck.nether.net>
Sent: Saturday, August 16, 2008 3:29 AM
Subject: Re: [c-nsp] ip cef load sharing


> Still seem to have the same problem even with this:
>
> interface FastEthernet0/0
> ip address 10.1.10.1 255.255.255.0
> ip tcp adjust-mss 1300
> duplex auto
> speed auto
>
>
> interface FastEthernet0/1
> ip address 192.168.10.1 255.255.255.0
> ip load-sharing per-packet
> duplex auto
> speed auto
>
> Dan.
>
> On Fri, Aug 15, 2008 at 12:49 PM, Rodney Dunn <rodunn at cisco.com> wrote:
>> On Fri, Aug 15, 2008 at 12:35:01PM -0500, Dan Letkeman wrote:
>>> ip load-sharing per-packet
>>>
>>> I tried adding this to F0/1 and the trace route works now(it randomly
>>> picks either line), but there seems to be issues with maybe the MTU?
>>> If I try to browse websites i get page errors and some of the pictures
>>> and pages don't load.
>>
>> Yep...try configuring "ip tcp adjust-mss 1300" or so on the
>> ingress interface from the LAN.
>>
>>>
>>> Any ideas?
>>>
>>> Thanks,
>>> Dan.
>>>
>>> On Fri, Aug 15, 2008 at 12:12 PM, Rodney Dunn <rodunn at cisco.com> wrote:
>>> > Try ip load-sharing per-packet on both egress interfaces.
>>> >
>>> > On Fri, Aug 15, 2008 at 12:00:46PM -0500, Dan Letkeman wrote:
>>> >> Hello,
>>> >>
>>> >> I have a 2621 router running 12.3(26) and I would like to setup load
>>> >> sharing to multiple adsl lines.  When I do a traceroute on the router
>>> >> it randomly picks a dsl line and seems to work fine.  But when I do
>>> >> traceroute tests from a workstation it always seems to take the same
>>> >> adsl line.  Is there something else I need to add to the 
>>> >> configuration
>>> >> to make it pick random lines, or is there a timeout of some sorts
>>> >> before it will select the next ip route
>>> >>
>>> >> Here is my config:
>>> >>
>>> >> !
>>> >> interface FastEthernet0/0
>>> >>  ip address 10.1.10.1 255.255.255.0
>>> >>  duplex auto
>>> >>  speed auto
>>> >> !
>>> >> interface FastEthernet0/1
>>> >>  ip address 192.168.10.1 255.255.255.0
>>> >>  duplex auto
>>> >>  speed auto
>>> >> !
>>> >> ip http server
>>> >> ip classless
>>> >> ip route 0.0.0.0 0.0.0.0 192.168.10.10
>>> >> ip route 0.0.0.0 0.0.0.0 192.168.10.11
>>> >> !
>>> >>
>>> >> The two adsl modem/routers I have are 192.168.10.10, and 
>>> >> 192.168.10.11
>>> >>
>>> >> Thanks,
>>> >> Dan.
>>> >> _______________________________________________
>>> >> 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/
>>> >
>>
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