[j-nsp] ECMP vs LAG and OAM vs BFD

[Jeff Richmond]

Guys, FWIW, I tested and cleared LFM over LAG for our core and it has worked very well. Ran in to some interesting things along the way, but in the end it behaves as advertised and is a huge step in the right direction, especially for detecting carrier outages where there is no Fault Propagation end-to-end. Ping me offline if you want to see what it looks like. 

Regards,
-Jeff

On Jul 22, 2011, at 1:27 PM, Rafael Rodriguez wrote:

> On Fri, Jul 22, 2011 at 4:14 PM, Stefan Fouant <
> sfouant at shortestpathfirst.net> wrote:
> 
>> On 7/22/2011 11:24 AM, Rafael Rodriguez wrote:
>> 
>>> 
>>> Interesting, did not know that control packets were always sent on the
>>> lowest numbered interface in a LAG.  Are you aware of any Juniper
>>> documentation mentioning this?  I found KB10926 but this is specific to
>>> EX and not MX. So LAG + BFD will do nothing in determining if individual
>>> links in the LAG are actually 'up'.  Thanks.
>>> 
>> 
>> I am not sure of any documentation but we do cover this in some of our
>> training materials.  I will see what I can dig up.
>> 
>> Regarding BFD's capabilities to determine member state of individual member
>> links, this is not currently supported by BFD.  Take a look at IETF Draft
>> 'Bidirectional Forwarding Detection (BFD) for Interface' which was just
>> released a few weeks ago. It is designed to meet these requirements -
>> http://tools.ietf.org/html/**draft-chen-bfd-interface-00<http://tools.ietf.org/html/draft-chen-bfd-interface-00>
>> 
>> In the meantime, why not just run LACP across your LAG interface?  This can
>> accomplish the goal quite easily.
> 
> 
> No sub-second failure detection, its 1-3 sec range.
> 
> 
>> 
>> 
>> Are individual links in the LAG able to detect failures with OAM?
>>> 
>> 
>> Should be able to but I would of course test it first... :)
>> 
> 
> Testing this now.  Found:
> http://www.juniper.net/techpubs/en_US/junos11.1/topics/example/layer-2-802-1ah-ethernet-oam-lfm-example-for-aggregated-ethernet-mx-solutions.html
> 
> 
> 
>> 
>> Stefan Fouant
>> JNCIE-ER, JNCIE-M, JNCIE-SEC, JNCI
>> 
>> Technical Trainer, Juniper Networks
>> http://www.shortestpathfirst.**net <http://www.shortestpathfirst.net>
>> http://www.twitter.com/sfouant
>> 
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