Solved

bgp question

Posted on 2002-05-20
6
381 Views
Last Modified: 2010-04-11
hi

we have a multihomed bgp environment with our own AS.
We have been given a /24 ip address range (which we have subnetted to use 4 subnets /26 - using the
all zero and all ones subnet)

Given that we have our own AS number and IP address range, is the AS number linked with our ip address
range? is this linked solely with the "network" command in BGP config?

see configuration below:

router bgp x
no synchronization
bgp log-neighbor-changes
network a.a.a.0
neighbor x.x.x.x remote-as 702
neighbor x.x.x.x description UUnet s2/1
neighbor x.x.x.x filter-list 1 out
neighbor y.y.y.y remote-as 5378
neighbor y.y.y.y description C&W s2/0
neighbor y.y.y.y filter-list 1 out

so whatever we put in for the network a.a.a.0

ie network a.a.a.0 is important, as this will be advertised out to other BGP As'es, for instance if
I changed this to another ip address range would this cause carnage on the internet? (not that i would!
our isps trusts us!)

We have been using neigbour y.y.y.y for 2 months. We added neigbour x.x.x.x today. How long would it
take for other BGP routers to have x.x.x.x listed as a alternative AS path (via AS 702)?? to our a.a.a.0
network address range?

Would it be possible for us to be a transit AS... i know that this is a bad idea.. but how is it configured?

Thanks
0
Comment
Question by:dbrannigan
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 5
6 Comments
 
LVL 1

Expert Comment

by:mmedwid
ID: 7022504
I believe you'd only want to be a transit AS if you are an ISP.  It souns like you are an enterprise - no?

Your ISPs probably have filters up to keep you from causing too much mayhem.   But without putting the whole block into your network statement - you risk folks not being able to reach those subnets that are excluded.  
0
 
LVL 1

Expert Comment

by:mmedwid
ID: 7030818
http://www.cisco.com/warp/public/459/bgpfaq_5816.shtml#6

Check out the entire faq actually.  
0
 
LVL 1

Expert Comment

by:mmedwid
ID: 7030820
Oops - this is the part I meant to call your attention to...

Q. How can I verify if a BGP router is announcing its BGP networks and propagating them to the global BGP mesh?
A. To check if the IP blocks are announced to the directly connected ISP, use the following commands. The show ip bgp neighbors [address] advertise-routes command shows which messages are being sent. The show ip bgp neighbors [address] routes command shows which messages are being received.
Note: The show ip bgp neighbors [address] advertise-routes command doesn't take into account any outbound policies you may have applied. In future IOS versions the command output will be changed to reflect the outbound policies.

To verify how the IP blocks are getting propagated to the global BGP mesh via the directly connected ISP, log onto a route server  on the Internet and look for the BGP entries of the prefix in the route server.
0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 1

Accepted Solution

by:
mmedwid earned 150 total points
ID: 7030821
And to see how you look from the perspective of the outside work...select any of the choices, select BGP and enter the block you are wondering about.

http://nitrous.digex.net/
0
 

Author Comment

by:dbrannigan
ID: 7141026
thanks mate.. sorry for the delay in accepting your answer!
0
 
LVL 1

Expert Comment

by:mmedwid
ID: 7141805
No problem.  Glad to be of assistance!  -Michael
0

Featured Post

Secure Your WordPress Site: 5 Essential Approaches

WordPress is the web's most popular CMS, but its dominance also makes it a target for attackers. Our eBook will show you how to:

Prevent costly exploits of core and plugin vulnerabilities
Repel automated attacks
Lock down your dashboard, secure your code, and protect your users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Join Greg Farro and Ethan Banks from Packet Pushers (http://packetpushers.net/podcast/podcasts/pq-show-93-smart-network-monitoring-paessler-sponsored/) and Greg Ross from Paessler (https://www.paessler.com/prtg) for a discussion about smart network …
When you try to share a printer , you may receive one of the following error messages. Error message when you use the Add Printer Wizard to share a printer: Windows could not share your printer. Operation could not be completed (Error 0x000006…
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…
Suggested Courses
Course of the Month3 days, 13 hours left to enroll

630 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question