From: Ali El Moussaoui (mousawi.ali@gmail.com)
Date: Thu Mar 19 2009 - 03:46:36 ART
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
>>>>
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>>>> _______________________________________________________________________
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>>>>
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>>>>
>>>> _______________________________________________________________________
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>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>> --
>>> Pavel Bykov
>>> ----------------
>>> Don't forget to help stopping the braindumps, use of which reduces value
>>> of your certifications. Sign the petition at
>>> http://www.stopbraindumps.com/
>>>
>>
>>
>>
>> --
>> Pavel Bykov
>> ----------------
>> Don't forget to help stopping the braindumps, use of which reduces value
>> of your certifications. Sign the petition at
>> http://www.stopbraindumps.com/
>>
>
>
>
> --
> Pavel Bykov
> ----------------
> Don't forget to help stopping the braindumps, use of which reduces value of
> your certifications. Sign the petition at http://www.stopbraindumps.com/
Blogs and organic groups at http://www.ccie.net
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