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Silver

Wake On LAN and Nexus 7K

Hi.

The server/workstation admin at $POE has dropped on me that he wants to start using Wake On Lan (WoL) to allow him to push software updates and packages to PC's which are not turned on, but which support WoL.

My internal network consists of a pair of Nexus 7010 switches at the core (which also host some server/workstation conectivity as well as concentration points for access switches) and WS-C4948-10G access switches running back to the Nexus'.

The core switches are running VPC's for the access switch uplinks and SVI's with HSRP for multiple VLAN capability (we have dozens of VLAN's for different purposes). The access switches do NOT have routing enabled - everything is via VLAN's and trunks to the Nexus' which do the intra-VLAN routing. We have a single DHCP server which serves only a couple of VLAN's (the rest are static IP addressing), and a single "software" which will be doing the WoL "magic" packet origination.

Does anyone know

1) If WoL is even supported by the Nexus switches?

2) Somewhere I could find a decent guide to configuring this in a similar environment 8without* breaking the DHCP server?

Everything I've seen seems to idnicate you have to put an IP helper address on the SVI to allow for the WoL server to be propogated across VLAN's - but the main subnet which needs the WoL stuff is one of the ones served by the DHCP server (which already had an IP helper address), and I'm worried that adding another IP Helper to the setup will break the DHCP allocation of IP addresses.

Any pointers appreciated.

Thanks.

Everyone's tags (3)
1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Wake On LAN and Nexus 7K

Here is a good doc on WOL:

http://www.cisco.com/en/US/partner/products/hw/switches/ps5023/products_configuration_example09186a008084b55c.shtml

https://www.ciscotaccc.com/kaidara-advisor/lanswitching/showcase?case=K74260926

Remember to configure ip forward-protocol udp 7 and ip directed-broadcast on the last hop router (nexus in this case).

WOL does not require directed-broadcasts unless you've got a host on a different subnet attempting to do it. if that is the case then you need to allow directed-broadcasts.

I have seen issues on access ports if ports were not set to auto auto.

Nothing special about the Nexus I am aware of.

In regards to possible conflict with the DHCP, make sure WOL is not using UDP/67 or you might run into some issues with DHCP snoop. I see the hosts using WOL and DHCP are on the same subnet but are the WOL and DHCP servers on the same subnet?


Fabienne.

6 REPLIES
Cisco Employee

Re: Wake On LAN and Nexus 7K

Here is a good doc on WOL:

http://www.cisco.com/en/US/partner/products/hw/switches/ps5023/products_configuration_example09186a008084b55c.shtml

https://www.ciscotaccc.com/kaidara-advisor/lanswitching/showcase?case=K74260926

Remember to configure ip forward-protocol udp 7 and ip directed-broadcast on the last hop router (nexus in this case).

WOL does not require directed-broadcasts unless you've got a host on a different subnet attempting to do it. if that is the case then you need to allow directed-broadcasts.

I have seen issues on access ports if ports were not set to auto auto.

Nothing special about the Nexus I am aware of.

In regards to possible conflict with the DHCP, make sure WOL is not using UDP/67 or you might run into some issues with DHCP snoop. I see the hosts using WOL and DHCP are on the same subnet but are the WOL and DHCP servers on the same subnet?


Fabienne.

Silver

Re: Wake On LAN and Nexus 7K

> Nothing special about the Nexus I am aware of.

You're right on that one - this Just Werked. :-)

Our server administrator decided to just try it anyway, and lo and behold, waking up PC's after a request from the WoL server.

To answer your question - yes, the WoL server and the DHCP server are on the same subnet, but I didn't have to do anything beyond my normal config - an, as far as I can tell, there's no explicit enable of ip direct-broadcasts on any SVI in the nexus.

So I'm going to follow the old adage - if it 'aint broke, don't fix it!

Thanks

New Member

Re: Wake On LAN and Nexus 7K

I am getting a report from a customer that ip forward-protocol is not supported on a Nx5548-UP.  I have read elsewhere that this is NOT supported, but being considered.  If I read the thread here correctly, the WOL clients, server and dhcp were all on the same subnet, so support of this doesn't require L3 forwarding.  Does anyone know if ip forward-protocol udp or ip directed-broadcast are available on Nexus 5K or 7K?

Cisco Employee

Wake On LAN and Nexus 7K

AFAIK, ip forward-protocol and ip directed-braodcast is not available on both N5K and N7K.

New Member

Hello,3 years later I asks

Hello,

3 years later I asks myself if an evolution occured or has been planned around forward-protocol implementation.

My Altiris architect would appreciate it ;-)

No news or plan ?

Best Regards,

/edu

New Member

I share the same question,

I share the same question, ist there a plan to add forwarding of WoL UDP broadcast?

It is poor to need an extra IOS device on the subnet just to forward this with old fashion ip-helper

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