Cisco Catalyst and HP Procurve UDLD compatible ?

[SRES-DGDSI@UGA]

Hello,

The Cisco Catalyst and HP Procurve switches support the UDLD protocol (Unidirectional Link Detection Protocol), but their implementations do not seem compatible. Some of you have they implemented this feature implemented between different brands of these switches? Cisco aggressive mode or normal? only on the fiber or copper also? are there other credible alternatives (LACP with LAG menbre one example)?

Thank you in advance for your lights

[Reza Sharifi]

Hi,

UDLD applies only to fiber ports, because usually a fiber interface comes with 2 strands (1tx and 1rx) and they can be misconnected. No need to apply it to copper interfaces. LACP and PAGP differ from UDLD.  They are not the same.

HTH

[Peter Paluch]

Hello Reza,

No need to apply it to copper interfaces.

Hmm, I usually tell my students that even if the UDLD may not be outright helpful on copper ports, it does not do any harm, so I recommend running it on copper ports, too. Note that if you are using some kind of repeater or external copper/fiber transceiver to which your switch is connected via a copper port, using UDLD may actually be called for, as the transceiver or repeater may introduce unidirectional link conditions.

Sadly, I cannot answer whether the UDLD as implemented by HP is compatible with Cisco's UDLD. I did not even think HP had UDLD implemented, as it is covered by Cisco patents.

Best regards,

Peter

[Reza Sharifi]

Hello Peter,

I agree, if you are using a repeater or a media converter to convert from copper to fiber and vice versa, it is a good idea to use UDLD, but if your interface is copper only even by adding coupler to make your cable longer, there is only one way you can connect an RJ45 interface. Of course, it doesn't harm anything if you added to all your interfaces, but not necessary.

Thanks,

Reza

[Giuseppe Larosa · Accepted solution]

Hello,

from HP website I have found an interoperability cookbook HP/Cisco but UDLD is not covered

see

http://h17007.www1.hp.com/vanity/hpiopcookbook.htm

As Reza noted UDLD functions are not covered by LACP. LACP is useful to detect unusability of a member link of a LAG bundle.

UDLD is Cisco proprietary but the protocol is described in one RFC 5171 this might allow for other vendors implementations.

http://tools.ietf.org/html/rfc5171

I would go for testing UDLD in normal mode. You can easily understand if things are going well or not because UDLD is effective if a neighbor has been detected on the link. So if you find UDLD neighbor on the link Cisco-HP the two implementations are compatible

Edit:

a link for UDLD configuration on HP switch

http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?lang=en&cc=us&taskId=120&prodSeriesId=1827663&prodTypeId=12883&objectID=c01978780

Hope to help

Giuseppe

[SRES-DGDSI@UGA]

Hello,

Thank you all for your answers.

The alternative using LACP with LAG consists of a single member is briefly described in this document Juniper: http://kb.juniper.net/InfoCenter/index?page=content&id=KB13314&actp=RSS

Hope this can give some ideas