Showing posts from May, 2017

How DevOps and Cloud raise the importance of System Integrator

System Integrators, buckle up, DevOps is coming, and if you play your cards right - your role is about to get crazy important.

Let me start this post by telling a story. It's a story that involves a stubborn customer, 3 big vendors and a Cloud. The reason I need to start this way is simple - the same scenario with different "players" has happened so many times in the last few years that someone should sum up what we've all learned (or haven't, in some cases). I guess this would be a great place for a Disclaimer, and  I'll quote my favourite disclaimer ever, from South Park: All Customers and events in this post, even those based on real people, are entirely fictional.

The story starts with Customer learning that Cloud is cool, and starting wanting it. The problem is that there is no manual on Google on how to build a personalised private cloud. That's no problem, why not just promote (rename) your head systems engineer to a Cloud Architect and follow his …

Cisco ACI Unknown Unicast: Hardware Proxy vs Flooding Mode

Before we start, lets once again make sure we fully understand what Bridge Domain is. The bridge domain can be compared to a giant distributed switch. Cisco ACI preserves the Layer 2 forwarding semantics even if the traffic is routed on the fabric. The TTL is not decremented for Layer 2 traffic, and the MAC addresses of the source and destination endpoints are preserved.

When you configure the Bridge Domain in the ACI, you need to decide what you want to do with the ARP packets, and what you want to do with the Unknown L2 Unicast. You can basically:

Enable ARP Flooding, or not.Choose between the two L2 Unknown Unicast modes: Flood and Hardware Proxy.

Hardware Proxy By default, Layer 2 unknown unicast traffic is sent to the spine proxy. This behaviour is controlled by the hardware proxy option associated with a bridge domain: if the destination is not known, send the packet to the spine proxy; if the spine proxy also does not know the address, discard the packet (default mode).

The adva…