Advertising a default route in BGP

There are four ways to distribute a default route in BGP.

Three of them, the network 0.0.0.0, the default-information originate and redistribution from another routing protocol, are all similar in the resulting effect: they will inject the default route into BGP RIB and it will be advertised to all BGP neighbors. The difference is in the origin of the default route that is injected into BGP. Specifically:

  • network 0.0.0.0 will inject the default route into BGP only if the default route is currently present in the routing table.
  • redistribution will inject the default route into BGP only if the default route is currently present in the routing table and if it has been learned by a specific source protocol we are redistributing from.
  • default-information originate causes the default route to be artificially generated and injected into the BGP RIB, regardlessly of whether it is present in the routing table. The newly injected default will be advertised to all BGP peers (because it now resides in the BGP RIB)

The fourth method:

  • neighbor X.X.X default-originate is similar to the default-information originate in that the default route is “artificially generated” (it does not need to be present in the routing table in order to make the advertisement effective)*.
  • However, the neighbor X.X.X.X default-originate is different from the the default-information originate in that the default route will be advertised only to this specific BGP neighbor and not to all existing BGP neighbors as with the previous approaches. The default route will not be installed in the BGP RIB of the router that is configured with the neighbor X.X.X.X default-originate command and so it won’t be generally advertised to all BGP neighbors.

*By doing the ‘default-originate’, you request a routerA (provider A) to send a route 0.0.0.0/0 via BGP out to RouterB (customer B).This is useful in many cases where customer B doesn’t really want toaccept a full BGP feed(for example in stub autonomous systems).

Building a SPS Solution

Using MangoES with 3/4g intergrated corporate connectivity for management & monitoring. 👌🏼

Cisco ACI Fabric Forwarding summary

Here’s a great summary of the ACI packet flow in conjunction with Spine and Leaf, a good watch if you have played with any of this technology, in any way. Thank you Lilian Quan. Very helpful 🙂

….and another good explanation, depending on the sex of your packet.

 

Reset Cisco IP Phone(7962) to the Factory Default

Complete these steps:

  1. Unplug the power cable from the phone, and then plug in the cable again.

The phone begins its power up cycle.

  1. Immediately press and hold# and while the Headset, Mute, and Speaker buttons begin to flash in sequence, release #.

The line buttons flash in sequence in order to indicate that the phone waits for you to enter the key sequence for the reset. (these are buttons on the right of the display)

  1. Press 123456789*0# within 60 seconds after the Headset, Mute, and Speaker buttons begin to flash.

If you do not complete this key sequence or do not press any keys, after 60 seconds the Headset, Mute, and Speaker buttons no longer flash, and the phone continues with its normal start-up process. The phone does not reset.

If you enter an invalid key sequence, the buttons no longer flash, and the phone continues with its normal startup process. The phone does not reset.

If you enter this key sequence correctly, the phone displays this prompt:

Upgrading……….

To verify advertised BGP routes within a VRF

We can verify each BGP address family now maintains routes for its respective VRF. In order to view the BGP routes for a specific VRF, use the following command:

router#show ip bgp vpnv4 vrf <%vrfname%> neighbors <%ipaddress%> advertised-routes