• Author : Steven King


How to source Splunk Forwarder traffic from a Loopback Interface

The diagram below describes the use case: SWITCH1 has a Splunk Forwarder that needs to send traffic to SPLUNK at  SWITCH2 is originating a default route via BGP. SWITCH1 is only advertising its Loopback0 interface into BGP.  The Splunk Forwarder CLI configuration does not currently support specifying a source interface, and in this scenario this is a problem because SWITCH3 has no route to reach, which would be the source IP for any traffic that SWITCH1 sends to SPLUNK.  SWITCH3 does however have a route to SWITCH1’s Loopback0 interface. We verify this by pinging SPLUNK from SWITCH1 and...
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How Rapid Spanning Tree Protocol (RSTP) Handles Topology Changes

For this exploration I’m using Arista’s Virtual Extensible Operating System (vEOS) version 4.15.0F running in GNS3(Which is pretty awesome).  The virtual switches have been configured in rapid-pvst mode. Here is the topology: EtherSwitches have been added only to capture traffic off of monitoring sessions set up on Switch1 and Switch2 to look at in Wireshark.  The Ubuntu server can be ignored for the purposes of this blog entry. Only VLAN 1 is present on all switches and Switch1 is configured to be the primary root, while Switch2 is configured to be the secondary. Here’s the current state of the network:...
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My journey with Ansible and Arista

Before I joined the ranks of Arista, my primary focus was technical refreshes and configuration documentation to support a PVST+ and OSPF architecture.  Yes – PVST+.  Yes – not RSTP.  I don’t say that to knock the place, I say that to give you an idea of where I’m coming from.  I was completely focused on spanning tree and routing protocols – primarily OSPF.  I had blinders on and didn’t want to do anything but routing and switching in a certain vendor’s world. Needless to say, transitioning from that place to working for Arista Networks was like Charlie stepping into...
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