Double-Sided vPC with N5k and Cat6500

1. Introduction

Here i want to explain, how to create a double-sided vpc in an enterprise environment.
A customer of us want to redeploy his ESX Server connection from active-passive to active-active.
In the past the ESX Server were single-sided connected to one of the N5k devices with two 10 Gbit links.
The ESX Server were bundled in a port-channel on both sides. (N5k <-> ESX)

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DHCP Discover Failure in a Port-Channel

1. Introduction

Yesterday we stumbled over an absolutely curious phenomenon in association with the DHCP
process and a port-channel. With a port-channel the DHCP discovery process fails.
Our network design is like cisco enterprise environment commended. There are an
access-layer -> distribution layer -> core layer (in direction to the core).
Everything works fine from the beginning from SW1 and SW2. DHCP discovery is
no problem and works fine. On switch 1-3 we have dhcp snooping operational.
The dhcp snooping trust settings are set to the uplinks and respectively to the port-channels.

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Calculate ACL with suitable mask

Last week i stumbled over a miracle, how to calculate the appropriate mask for a special ip range.
My colleagues and i discussed arp inspection and a strange associated acl setting method.
I never ever see a acl like this:

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