BGP Scalability Sample Nugget – Route Reflectors

October 3, 2018 at 10:39 pm

route reflectors

This Nugget is from my BGP – Scalability course at CBT Nuggets. This is one of 6 courses I created on BGP for you! Here we examine BGP Route Reflectors.


Pearson Education (InformIT)

Wrapped the Latest BGP Module at CBT Nuggets Today!

September 21, 2018 at 7:39 pm

BGP

That’s right- finished up the last Nugget today for the course below. I will post again here at the blog when the course appears on the CBT Nuggets website next week!

Border Gateway Protocol (BGP) – Scalability Mechanisms

  1. Module Introduction
  2. Private AS Numbers
  3. Peer Groups
  4. Session Templates
  5. Policy Templates
  6. IBGP Scalability Issues
  7. Route Reflectors
  8. Advanced Route Reflector Designs
  9. Confederations
  10. Configuring a Confederation
  11. Introduction to BGP Communities
  12. Community Attribute Formats
  13. Well-Known Communities
  14. Extended Communities
  15. Configuring BGP Communities

Remember, this is one more BGP module to complement the existing modules currently on CBT Nuggets:

  • BGP – Basic Operations
  • BGP – Peerings
  • BGP – Advertising NLRI
  • BGP – Cisco Routing Policy Mechanism

BGP Processes in the Cisco IOS

August 21, 2018 at 10:32 am

BGP

These are some notes that I used to help teach a recent module in my upcoming Border Gateway Protocol (BGP) – Cisco Routing Policy Mechanisms course at CBT Nuggets. Enjoy!

There are many processes that work together to provide BGP services in the Cisco IOS. To see those that are running on your IOS version (and hardware), run the following command:

show processes cpu | include BGP

There are four core processes you should definitely see:

  • I/O – this process is responsible for moving prefixes in and out of the appropriate InQ and OutQ mechanisms; this allows us to both send and receive prefix information
  • Router – this process is the workhorse of the BGP system and takes care of policy application and the BGP Best Path Decision Algorithm
  • Scanner – the scanner process defaults to one minute intervals of operation; you can change this with the bgp scan-time command under the BGP configuration; this process is scanning for changes that might require a revamp of the BGP information (an example would be a prefix removal due to next hop reachability issues)
  • Scheduler – this process is responsible for scheduling the various BGP processes that might be running

To see the Scanner process in action – you can use the command – debug ip bgp events

Remember, you might see other BGP related processes running on your system. Cisco is constantly working hard on their implementation to improve efficiency and reduce CPU workloads. For example, you might see:

  • BMP Server – this service permits the functionality of BGP Monitoring Protocol for neighborships
  • Event – this service helps the Scanner with its potential workload – it quickly responds to events like network statement introduction and redistribution commands
  • NHT – a next hop tracker process that, again, assists the Scanner service with its work
  • Open – you might get lucky and catch a glimpse of this process – it exists to assist with neighbor formation

Border Gateway Protocol (BGP) – Advertising NLRI is Complete!

June 21, 2018 at 2:59 pm

BGP

I have completed the final videos and quizzes for the latest module on BGP I am recording at CBT Nuggets. Here is a recap of the videos so far!

Border Gateway Protocol (BGP) – Basic Operations (Released Jan 2018)

https://www.cbtnuggets.com/it-training/border-gateway-protocol-basic

  1. An Overview of BGP
  2. BGP Message Types
  3. BGP Message Formats
  4. BGP Neighbor States
  5. BGP Path Attributes
  6. The Origin Attribute
  7. The AS_PATH Attribute
  8. The NEXT_HOP Attribute
  9. BGP Weight
  10. BGP Best Path Selection

Border Gateway Protocol (BGP) – Peerings (Released Feb 2018)

https://www.cbtnuggets.com/it-training/border-gateway-protocol-peerings

  1. eBGP Peerings
  2. Cisco eBGP Peering Example
  3. Juniper eBGP Peering Example
  4. iBGP Peerings
  5. Cisco iBGP Peering Example
  6. Juniper iBGP Peering Example
  7. eBGP Multihop
  8. Using BGP Authentication
  9. Misc. Neighbor Options

Border Gateway Protocol (BGP) – Advertising NLRI (Released June 2018)

https://www.cbtnuggets.com/it-training/border-gateway-protocol-advertising-nlri

  1. The Cisco Network Command
  2. Cisco Troubleshooting for NLRI Reachability
  3. Redistributing NLRI in Cisco BGP
  4. Cisco BGP RIB Failures
  5. BGP Synchronization
  6. Juniper NLRI Advertisement
  7. Static Routes with Multihoming
  8. Redistributing NLRI into IGPs
  9. Using iBGP with a Stub AS
  10. Advertising a Default Route
  11. BGP Aggregation

Border Gateway Protocol (BGP) – Cisco Routing Policy Mechanisms (Releasing July 2018)

  1. An Overview of BGP Routing Policy
  2. The BGP Decision Process
  3. A Routing Policy Example
  4. InQ and OutQ
  5. Cisco IOS BGP Processes
  6. Next Hop Tracker, Event, and the Open Processes
  7. Table Versions
  8. Clearing BGP Sessions
  9. Soft Reconfiguration
  10. Route Refresh

Manual Summarization with BGP on Cisco Routers

March 22, 2018 at 8:57 pm

BGP

One of the topics that will be featured in my upcoming CBT Nuggets module, Border Gateway Protocol (BGP) – Advertising NLRI, manual route summarization in BGP. This post serves (as well as more to follow) cover the highlights of the video coverage.

There are two methods of performing aggregation with BGP on a Cisco router. You can create a static route that represents the aggregate and then advertise that route using the network command. Or, you can use the aggregate-address command.

Here is an example of the static route approach:

router bgp 65100
   network 192.168.192.0 mask 255.255.248.0
   neighbor 192.168.1.220 remote-as 65200
!
ip classless
ip route 192.168.192.0 255.255.248.0 Null0

Notice how the static route directs to the bit bucket (Null0). This is because it is not an actual network destination. It is an artificial construct to permit the route in the routing table so we can use the network command in BGP. There will be more specific entries in the routing table covered by this advertised summary and the router can follow those instructions. Should all the more specific entries be removed, then the static route has traffic discarded for the summary (this is the desired behavior, typically).

With the aggregate-address command approach, you ensure component routes of the summary exist in the BGP table (thanks to the network statement or redistribution), and the summary address is advertised via BGP. Here is an example:

router bgp 65100
 aggregate-address 192.168.192.0 255.255.248.0 summary-only
 redistribute eigrp 100
 neighbor 192.168.1.220 remote-as 65200

Note that if you forget the summary-only keyword with the aggregate-address command, you will advertise the summary as well as the specific routes. A future post will demonstrate when this approach might be useful.