Archive for September, 2008

Working a lot!

Monday, September 29th, 2008

I have been working a lot lately, we are in the proccess of designing a new data center with all the ifs ands and buts included in that ordeal. I am in the proccess of writing several write ups,


Encrypting GRE tunnels!

Monday, September 8th, 2008

In our Last article we looked at creating GRE tunnels between networks to allow non-routable traffic to pass between remote offices.  GRE tunnels are a great solution however the traffic passing inside these tunnels is not encrypted and thus could be intercepted by unauthorized parties. In this article we are going to look at tunneling GRE inside of IPSEC. This will allow us to get the benefits of GRE and the security of IPSEC.



Create a GRE tunnel between endpoints!

Monday, September 8th, 2008

Many time it is necessary to link a remote office to your main site and today we have many technologies to accomplish this task. We have IPSEC tunnels, IP-IN-IP tunnels, and GRE or Generic Routing Encapsulation Tunnels.

Each type of connectivity offers advantages and disadvantages. Some of these tunnels can even be overlaid on top of one another. For instance IPSEC can be used in a transport mode, which allows you to use the encryption with other tunnels or protocols. For this article we are going to discuss GRE tunnels. GRE is unique as tunneling technologies go in that is started out as a proprietary protocol developed by Cisco and later adopted as a standard. GRE was invented as a way of encapsulating non routable protocols in IP which is a routable protocol. In this way protocols such as multicast (this include OSPF, EIGRP), and other protocols like IPX could be tunneled across routable links.


Cisco 3750 Switches now include a time domain reflectometer!

Monday, September 8th, 2008

How many time have you wanted to know how long a cable run was? Now if you are running cisco 3750 switches you can find out by issuing the following commands you can see how long that cable run really is.

Switch# test cable-diagnostics tdr interface gigabitethernet0/2
TDR test started on interface Gi0/2

A TDR test can take a few seconds to run on an interface. Use "show cable-diagnostics tdr" to read the TDR results.

Switch#show cable-diagnostics tdr interface gigabitEthernet 0/2
TDR test last run on: Dec 10 09:05:10

         Interface Speed Local pair Pair length Remote pair Pair status 
         --------- ------ ---------- ------------ ------------ ---------- 
         Gi0/2 auto Pair A   22 +/- 4 m N/A Open 
           Pair B    21 +/- 4 m N/A Open 
           Pair C    5 +/- 4 m N/A Open 
           Pair D    20 +/- 4 m N/A Open 

Checkpoint —> juniper VPN

Thursday, September 4th, 2008

Recently at work we had a remote site go down. The site was on an ancient pix 506e vpn firewall router. We were in the proccess of switching to a different vpn solution. because of this we had a new Juniper ssg20 firewall device on site.


Cisco 3640 and wic-1adsl speed problems

Tuesday, September 2nd, 2008

I recently decided to plug my wic-1adsl card into a 3640 router because my 2620 had a power supply failure. I noticed that the cisco 3640 ran very slow, and speed tests topped out at 2.6mbps downlink speeds. For a while I couldn’t figure out why a router that is faster with more memory would run slower than my 2620 router. I later discovered the reason for the slowness was because of a bandwidth limit on the nm-1fe1r2w card I was using to give me wic slots. (more…)

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