From: Jared Scrivener (jscrivener@ipexpert.com)
Date: Thu Mar 19 2009 - 04:06:22 ART
Try it without ebgp-multihop but using "disable-connected-check" instead.
See if that works - I've never tried them (dmzlink-bw and
disable-connected-check) together, but it might do the trick.
Cheers,
Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Sr. Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: <mailto:jscrivener@ipexpert.com> jscrivener@ipexpert.com
From: Ali El Moussaoui [mailto:mousawi.ali@gmail.com]
Sent: Thursday, 19 March 2009 2:47 AM
To: Pavel Bykov
Cc: ron.wilkerson@gmail.com; Jared Scrivener; Cisco certification
Subject: Re: BGP unequal load balancing
Guys, I tried the dmzlink-bw with ebpg-multihop greater than 1 and it
failed.The router threw an error stating that this option is only allowed on
directly connected neighbours (ebgp-multihop = 1)
On Wed, Mar 18, 2009 at 1:46 PM, Pavel Bykov <slidersv@gmail.com> wrote:
Uh... no, not junk.
There is no perfect load balancing algorithm (that I know of).
MLPPP, Etherchannel, CEF, you name it. Eveything has it's drawbacks.
Some of them are obvious, like differences in flow nature. Some of them are
more subtle, like polarization of ether channels.
Remember, one flow is never a good reference.
On the other hand, if you have 20000 flows, then you'll see that load
balancing doesn't work that bad.
On Wed, Mar 18, 2009 at 12:49 AM, <ron.wilkerson@gmail.com> wrote:
I understand all that but unless there is some background communication
between cef and bgp, the load sharing based on bandwidth isn't possible.
Even if cef distributes the buckets to a proper ratio, based on the
bandwidth, that still doesn't mean that the multiple paths will be used
according to cef's ratio.
Using your example, if one of the 5 hashes, given to the slower link
generates more traffic than the faster link, then this whole load sharing
based on bandwidth doesn't work.
The only way for this feature to work properly is for bgp and cef to monitor
the interface utilization, and along with that info, decide which path to
take. I know this doesn't happen, so I think this feature is junk.
_____
From: Pavel Bykov
Date: Tue, 17 Mar 2009 23:23:34 +0100
To: <ron.wilkerson@gmail.com>
Subject: Re: BGP unequal load balancing
By estimation.
I'm not sure exactly how it would be done in this case, but CEF balances per
SRC/DST pair by default.
To see what CEF choose some IOSes display the actual internal CEF table,
with 16 CEF entries for every destination network.
On most IOSes you can see CEF's choice using "show ip cef exact-route
SRC-ADDR DST-ADDR" command.
If the ration is say 20:5, then out of 16 CEF entries, 4/5 will be sent to
one link and 1/5 to the other. Every SRC/DST pair generates a hash - from 1
to 16. In this case 3 hashes are assigned to one interface, and 13 to the
other.
So there is a bigger chance that a flow will be assigned to that interface
with bigger hash probability.
On Tue, Mar 17, 2009 at 10:55 PM, <ron.wilkerson@gmail.com> wrote:
Then I don't see how this feature will work...
And bgp is not going to keep track of bandwidth utilization....so how does
this work exactly...
_____
From: Pavel Bykov
Date: Tue, 17 Mar 2009 22:33:06 +0100
To: <ron.wilkerson@gmail.com>
Subject: Re: BGP unequal load balancing
No, it's still flow based till you switch it. It will TRY to load balance.
By no means it means that it will be successful.
On Mon, Mar 16, 2009 at 4:45 PM, <ron.wilkerson@gmail.com> wrote:
Follow up question...
Always wondered how bgp's unequal load sharing worked with cef. Since the
traffic count will be unequal when using this feature, is the router now
performing per packet load sharing?
Example, with two paths (unequal)
The traffic count for 1st will be, say 5.
The 2nd is 3.
Wouldn't this lead one to believe that the router is load sharing per packet
instead of the default flow based?
-----Original Message-----
From: "Jared Scrivener" <jscrivener@ipexpert.com>
Date: Mon, 16 Mar 2009 11:25:28
To: 'Ali El Moussaoui'<mousawi.ali@gmail.com>; 'Cisco
certification'<ccielab@groupstudy.com>
Subject: RE: BGP unequal load balancing
Hey Ali,
Try using the "dmzlink-bw" command on your neighbor statements and the "bgp
dmzlink-bw" command within the BGP process. Also, you'll need to set
"maximum-paths" to 2 (or higher)from within the BGP process (to enable
load-balancing).
Cheers,
Jared Scrivener CCIE3 #16983 (R&S, Security, SP), CISSP
Technical Instructor - IPexpert, Inc.
Telephone: +1.810.326.1444
Fax: +1.810.454.0130
Mailto: jscrivener@ipexpert.com
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of Ali
El Moussaoui
Sent: Monday, 16 March 2009 11:06 AM
To: Cisco certification
Subject: BGP unequal load balancing
Hello Experts,
Is there a method *unequal* Load Sharing When Dual-Homed to One Internet
Service Provider (ISP) Through a Single Local Router?
I have 2 links to the Service Provider (20MB and 6MB). I am recieving the
full internet routing table from both links I need to load balance with a
ration of 20 : 6 is that possible?
Blogs and organic groups at http://www.ccie.net <http://www.ccie.net/>
This archive was generated by hypermail 2.1.4 : Mon Apr 06 2009 - 06:44:05 ART