j2sw’s blog

Recently there have been discussions on some lists about carrier redundancy.  I figured I would sum up some thoughts and add my own,

In today's world of consolidation, takeovers, and cost saving measures carrier redundancy is something one should pursue with due diligence.  Below are some questions to know about your existing provider and any future providers. If you know this you can compare the two.

1.Where does my circuit go when it leaves my equipment? Look at this from a regional perspective.  Where does it travel in the city? Where does it travel to the next city?
2.Does the provider's lines share conduit with other providers?  They might not know this, but if you have two providers you can compare routes.  If they are in the same conduit or in separate conduit in the same trench that might not be ideal.  A backhoe could take both out.
3.Where is the entry point for the provider's circuits. This is the same as #2.  If both come in to the same part of the building this could be a potential weak point.  Ideally one would enter from the north (or south or whatever) and the other would enter from a different direction.  Also they would travel up different conduits on different sides of the building.  This way if something like a car crashes through the building maybe one of them will be protected.
4.Do they share space along the path with other carriers? If so this could cause issues with contract disputes, not paying bills, and other business related functions.  Imagine if carrier A is sharing conduit with carrier B. Carrier A goes out of business and holds the conduit contract.  Where does that leave carrier B?

Also look at this from your own equipment perspective. If you terminate all your circuits on a single router you are dependent on that router. Same goes for anything.  If everything comes in over the same ladder racks that is a point of failure.   If all your equipment is in the same room that is a point of failure.

Redundancy can be as diverse as you want to. It boils down to mitigating the risk.  If you know all the risks you can say "Yeah I am willing to bring my cross connects over a single ladder rack because the likely-hood of that rack failing is a risk I will take." 
 

Recently there have been discussions on some lists about carrier redundancy.  I figured I would sum up some thoughts and add my own,

In today's world of consolidation, takeovers, and cost saving measures carrier redundancy is something one should pursue with due diligence.  Below are some questions to know about your existing provider and any future providers. If you know this you can compare the two.

1.Where does my circuit go when it leaves my equipment? Look at this from a regional perspective.  Where does it travel in the city? Where does it travel to the next city?
2.Does the provider's lines share conduit with other providers?  They might not know this, but if you have two providers you can compare routes.  If they are in the same conduit or in separate conduit in the same trench that might not be ideal.  A backhoe could take both out.
3.Where is the entry point for the provider's circuits. This is the same as #2.  If both come in to the same part of the building this could be a potential weak point.  Ideally one would enter from the north (or south or whatever) and the other would enter from a different direction.  Also they would travel up different conduits on different sides of the building.  This way if something like a car crashes through the building maybe one of them will be protected.
4.Do they share space along the path with other carriers? If so this could cause issues with contract disputes, not paying bills, and other business related functions.  Imagine if carrier A is sharing conduit with carrier B. Carrier A goes out of business and holds the conduit contract.  Where does that leave carrier B?

Also look at this from your own equipment perspective. If you terminate all your circuits on a single router you are dependent on that router. Same goes for anything.  If everything comes in over the same ladder racks that is a point of failure.   If all your equipment is in the same room that is a point of failure.

Redundancy can be as diverse as you want to. It boils down to mitigating the risk.  If you know all the risks you can say "Yeah I am willing to bring my cross connects over a single ladder rack because the likely-hood of that rack failing is a risk I will take." 
 

DOT1Q tunnel is a way of allowing any vlans to pass though a provider's network. a QinQ tunnel is also referred to as "VLAN Stacking".  This way you do not have to worry about overlap of vlans you would have in a normal switched network.   QinQ is used quite a bit in Metro Ethernet because it offers the following benefits:
-Security via isolation of customer traffic
-Backward compatibility preserving existing customer VLAN structures
-Simplicity via unburdening the service provider from configuration management of CE devices
-VLAN scalability (with up to 4K private VLANs per subscriber for up to 4K subscribers)

What happens is the end user network "wraps" their vlans within the access vlan at both ends.  From the send side it works like this:

Packet leaves the customer's switch on vlan 10 (see our example below).   This packet might contain information for a vlan of the customer's choosing. In our example we will say the customer is wanting to pass vlan 30 through to the other side.  When it enters the provider's switch on vlan 10 it is allowed to pass through the network over the trunk.  The provider just sees this as vlan 10.  Once it leaves the trunk port into the customer switch on the other side it is "unwrapped" from VLAN10. 

Dot1q

In order for QinQ to work across the entire network and additional overhead on the MTU must be accounted for.  Most ethernet providers doing multiple IP-IP tunnels and other such things already are raising the MTU to account for these so adding QinQ is not that big of a deal.  With some Cisco switches you are able to raise the MTU on a per port basis if need be.

I am wondering if the majority of the internet cares about an e-mail discussion being "top posted" or not.  Thoughts? opinions? It seems this comes up less and less these days. Was wondering if those who do bring it up are the die hard old-timers.

techmeme.com has no stories about twitter. Holy cow. They seem to love stories about twitter.

www.cellcrypt.com
UK ‘stealth mode’ startup Cellcrypt has started touting a new encryption system that sets out to solve a security problem most companies would rather not think about – insecure mobile phone calls.

Random Cisco Tip

To restart or reboot a Cisco in a certain number of minutes, in enable mode:
Router#reload in 5


http://news.techworld.com/operating-systems/3201232/snow-leopard-update-in-the-works-already/

One of the reasons I have been holding off on my day-to-day machine.

I recently filled out a University of Phoenix online thing to request more information.  Since Friday I have received 27 calls from them!  To me this is a little much, especially over a Holiday weekend.  They seem like more of a used car lot than a University at this point.  27 calls in a 3 day period is a little much.