Distributed Trunking - what is now mutual exclusive?

[Phix]

Hi there,

we are going to revisit our network. Currently we have

core1: 5406

core2: 2910al

(connected with 10GbE)

At the moment they "only" serve our virtualization environment via balance-tlb (one host is connected to both switches) for xen-traffic, data and iSCSI.

All downlinks to the edge switches are only connected to core1 (via LACP) at the moment.

On my recherche through the web I stumbled accross distributed trunking which seems to be the jack of all trades for our virt-cluster (I know that the 2910 is not capable of DT, but we would go for a new redundancy-core then).

But I stumbled about some downsides and on some contradictory announcements:

* A lot of sources state that IP routing is not possible with DT enabled - other source state that this should be possible with never firmware

* official 5400 page on HP ProCurve ( 1. ) state that DT is possible to servers AND switches - all other sources I found state that only connection to servers is possible

* All source I found state that IGMP is not supported with DT

Ideal scenario would be to use DT-LACP for the servers and the downlinks to the edge switches to achieve redundancy and the full LACP performance. But we need routing and IGMP support.

Any ideas and suggestions? Any answers to these three points?

Thanks a lot in advance,

phix

ressources:

1.) http://h17007.www1.hp.com/us/en/networking/products/switches/HP_5400_zl_Switch_Series/index.aspx#tab=TAB2

[Vince_Whirlwind]

My understanding was that it does not apply to switch-switch links, only switch-server.

A couple of years ago my colleague set this up and proved it worked, but we never brought it into any production environment as we preferred the option of moving to A-series or Juniper switches and using IRF instead.

[Aarón]

Hi,

DT trunking do work with switches, I advise you to use DT-LACP and LACP as these prevents possible loops.  As soon as you create a dt it disables STP in those links.

If you really need to use IGMP maybe you should just use redundant links with MSTP enabled. This way you can have redundancy with the other requirements you chose, the only problem is that the redundancy is not as fast as with DT.

Kind regards,

Aarón

[Vince_Whirlwind]

OK, DT-LACP for downstream devices was changed to include servers at some stage in K15 maybe?:

http://h20000.www2.hp.com/bizsupport/TechSupport/CoreRedirect.jsp?redirectReason=DocIndexPDF&prodSeriesId=1827663&targetPage=http%3A%2F%2Fbizsupport1.austin.hp.com%2Fbc%2Fdocs%2Fsupport%2FSupportManual%2Fc03724611%2Fc03724611.pdf

This allows third party devices such as switches, servers, or
any other networking device that supports trunking to interoperate with the distributed trunking
switches (DTSs) seamlessly.

Features not supported include:
• SVLANs in mixed mode on DT or ISC links
• Meshing
• CDP
• GVRP
• Multicast routing
• IPv6 routing
• MLD/MLD snooping on DT VLAN

[Phix]

Thanks for your answers! Really appreciate it (and gave Kudos ;-) )

That PDF only states that Multicast Routing is not possible. Do you think/know if normal IGMP snooping support is possible (ip igmp)?

Because then everything would be possible for us and I do the Multicast Routing on an external device and reingest them into the few VLANs where we need em.

Phix

[Aarón]

Hi,

from the Management and configuration guide K.15.09:

Configuring Distributed Trunking
The following parameters must be configured identically on the peer devices or undesirable behavior in traffic flow may occur:
  ■ The ISC link must have a VLAN interface configured for the same VLAN on both DT switches.
  ■ VLAN membership for all DT trunk ports should be the same on both DT switches in a DT pair.
  ■ IGMP-snooping or DHCP-snooping configuration on a DT VLAN should be the same on both DT switches. For example, for a DT, if IGMP-snooping or DHCP-snooping is enabled on a VLANthat has a DT port as a member port of the VLAN, the same must be configured on the peer DT on the same VLAN.

  ■ Loop-protection configuration on a DT VLAN should be the same for both DT switches.

It seems it should work but I have not tried it.

Aarón

[Phix]

Thanks for that nice find! I will file a request to our management for a second 5406 now ;-)

Thanks for all your help guys, really appreciate it.

phix