CCIE or Null!

My journey to CCIE!

Archive for September 2011

Blogging for a year now!

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Well, I’ve been blogging for a year now. This seems like the perfect time for me to reflect back on the things I’ve done over the last year. The new technologies I’ve learned, my professional and personal accomplishments. In my year of blogging I’ve published 30 articles, and I’ve got 14 articles in my drafts bin so I got a lot more information to get out. When I first started my blog I only had a dozen or so hits, now a year later I’m getting 1200-1500 views a month and for that I just want to say thank you for visiting. I do hope some of my articles have helped you out and provided you with some good information!!

Throughout the course of the last year and my blog, I’ve learned and passed my CWTS, CCDA, and Server+ exams! I was pursuing my CWNA but because I took a new job for a managed services provided designing and managing/maintaining networks around the world I had to withdraw from my CWNA studies, which explains why my last few articles have shifted from WLAN technologies to a more routing nature, I’ve also been diligently studying to acquire my CCIP certification so expect to some more BGP information from me as well some MPLS and QoS material. I also see some IPSec, Firewall, GRE, and other layer three topics showing up here on my blog in the future, so stay tuned for some more good info!

My Top 5 articles:

  1. Cisco Band Select with 998 views
  2. Cisco WLC Interfaces with 656 views
  3. Understand a Wi-Fi Connection with 590 views
  4. Wireless Networking and the 5 GHz RF Range with 469 views
  5. Cisco Band Select and Client RSSI with 369 views.
Totals visits to my blog to date: 10,845!!!


Steve Occh

Written by Stephen J. Occhiogrosso

September 27, 2011 at 8:44 AM

Posted in Update

Watching BGP neighbors form.

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BGP can be considered quite the routing protocol and typically tends to intimidate those that do not fully understand it. So I’m basically going to start from the ground up here and start from the forming of BGP neighbors.

Here is our topology, something nice and simple.

Now we are going to configure the BGP neighbor statements on our two routers.

While I run the debug ip bgp ipv4 unicast command on Router2:

From the debug output we see the two routers form a neighbor relationship as it goes through all of its phases.

  1. It starts from the Idle state, Idle is the phase that any BGP connection starts.
  2. Now you see move from Idle to Active in the Active state the BGP device is still trying to setup BGP session with its peer.
  3. Then you see we go from Active to OpenSent which shows we received a BGP Open message from the peer.
  4. Now continuing over the next few lines, you see this device sending out its Open message with its BGP version, AS number, and hold time. After that you will see the device receive an Open message from it’s neighbor and acknowledge its neighbor’s BGP capabilities.
  5. Now third line from the bottom we will see the status go from OpenSent to OpenConfirm, in this phase the BGP peers are simply waiting to receive a keep alive from the other.
  6. Then almost immediately we go from OpenConfirm to Established, and the BGP neighbor is up.
To verify this we will issue the sh ip bgp nei summary command and verify the neighbor has been up for the last 5 seconds and no prefixes have been received. If the neighbor ship was not up then it would tell us the State of the adjacency (instead of the number of prefixes received).

Written by Stephen J. Occhiogrosso

September 6, 2011 at 6:43 AM

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