OUCS Backbone Network Naming and Numbering Conventions

Introduction This blog post is intended to help ITSS in Oxford to better understand how the centrally provided network fits together with their own local networks. It is also hoped it will assist them in assessing the impact of any … Continue reading

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MAC Flaps – why are they bad?

What is a MAC Flap? A MAC Flap is caused when a switch receives packets from two different interfaces with the same source MAC address. If this makes no sense, perhaps a  quick summary of how switching at layer 2 … Continue reading

Posted in Backbone Network, Best Practices, Cisco Networks | Tagged | 3 Comments

Surprise! You have IPv6 connectivity!

I bet you didn’t think you had IPv6 connectivity yet (certainly in any University department). After all we’re still working through our plan to light up IPv6 services in the core. Well, news flash: if you’re running Windows 7 in … Continue reading

Posted in Backbone Network, IPv6 | 2 Comments

Update to our IPv6 Allocation Scheme

After gaining some experience in configuring IPv6 networks, and also receiving feedback from others, I’ve revised our IPv6 Allocation Scheme. This is the document which lays out how we intend to allocate networks to departments and colleges, and other services … Continue reading

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Changes in the core

On Tuesday 2nd March we made two significant changes in the Core. Both are inline with current Cisco best practice are have been implemented as part of our Backbone ‘feature update’ project. VTP We have moved to using VLAN Trunking … Continue reading

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Connecting to JANET

Sorry it’s been a little while since our last post. We’re just coming to the end of the summer vacation, the point when we (and most other IT support staff around the university) get things ship-shape in time for the … Continue reading

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Moving to a new ARP and MAC logging system

To locate a node (workstation, printer, etc) on the network, you use a combination of the ARP logs from a router, and the MAC-port mappings from a switch. The ARP log translates IP to MAC, and the MAC-port log translates … Continue reading

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