[f-nsp] Foundry and Cisco UDLD different?

[Mike Allen]

UDLD is what you are enabling by using the link-keepalive commands.  It
references Uni-Directional Link Detection, and this is incompatible between
vendors, as there is no universal standard.  There are some options that may
or may not work for you, depending on the interface (media) type, such as
LFS, RFN, or some tweaks that have been made to LACP.  The basic problem
that any of these solve is the one of a single fiber failure in a multiple
interface link.  Normal behavior in the past would be for the link still
recieving light (intact recieve path) would stay up, even though the
transmit side of that same link was broken.  The fact that the link stays up
prevents the switch from failing over to a failover or redundant (trunk)
link, and blackhole traffic down a broken fiber when there are alternate
paths available. Hope that helps.

Mike
On Jan 7, 2008 8:18 AM, Chris Gauthier <cgauthie at pcc.edu> wrote:

> Pardon my ignorance, but what is UDLD?
>
> Chris
>
>
> Andreas wrote:
>
> I would guess that they are incompatible thehttp://www.ietf.org/internet-drafts/draft-foschiano-udld-03.txt is
> preatty new and I guess that the "standards" for it isn't implemented
> correct in one of the platform. I  guess you could ask Foundry or Cisco
> if they do support UDLD between different vendor devices.
>
> Regards Andreas
>
>
> On Mon, 2008-01-07 at 16:50 +0100, Christian Bering wrote:
>
>
> Hi all,
>
> Googling the archives I haven't been able to come up with an answer to
> subj.
>
> I am unable to establish UDLD between a Cisco 7600 and a Foundry MLX.
> I have tried setting the Foundry values to what I think is default on
> Cisco, but with no luck:
> SSH at dr1.nybf#show link-keep
> Total link-keepalive enabled ports: 1
> Keepalive Retries: 5    Keepalive Interval: 7 * 100 MilliSec.
>
> Port    Physical Link   Link-keepalive  Logical link
> 1/3     up              down            down
>
> cr1.hors#show udld tenGigabitEthernet 4/1
>
> Interface Te4/1
> ---
> Port enable administrative configuration setting: Enabled
> Port enable operational state: Enabled
> Current bidirectional state: Unknown
> Current operational state: Advertisement
> Message interval: 7
> Time out interval: 5
> No neighbor cache information stored
>
> Are they incompatible or am I just using wrong values?
>
> Thanks,
>
> Christian Bering
>
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>
> --
> Chris Gauthier, CCNA, Network+, A+
> Network Administration Team
> Portland Community College
> Portland, Oregon
>
> "For once you have tasted flight you will walk the earth with your eyes turned skywards, for there you have been and there you will long to return."
> --Leonardo da Vinci
>
>
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