03-11-2012 06:29 PM - edited 03-04-2019 03:37 PM
Hello,
Understand how iBGP and eBGP work, can anyone tell me what are the pros and cons between these protocols? Any documentation is greatly appriciated.
Regards,
Joe
Solved! Go to Solution.
03-12-2012 02:50 AM
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Posting
Joe Lee wrote:
Understand how iBGP and eBGP work, can anyone tell me what are the pros and cons between these protocols? Any documentation is greatly appriciated.
If you understand how both work, then you realize the determinant is whether to BGP peers are using the same AS or a different AS. For routine eBGP, you're peers are very likely to use different ASs, so you wouldn't have a choice. For internal BGP usage, I suppose you could use different (private?) ASs, down to individual BGP peers allowing them to operate with eBGP rules.
The pros and cons of using eBGP internally vs. iBGP would be due to the differences in peering rules and routing rules. With eBGP rules you don't need to create a full mesh as you do with iBGP (or reflectors or confederations). With eBGP rules, you're less likely to require another IGP if the peers share a common subnet, or if they don't, need special multi-hop configuration along with extra routing information external to BGP itself. With eBGP rules, AS hops might indicate actual best path.
Although in theory I guess you could use eBGP rules with private ASs within the same logical AS, it could make it difficult to peer with more then one external public AS. In other words, this isn't normally a choice, so curious how you envisioned using pros and cons to select between eBGP vs. iBGP.
PS:
NB: "***" = Plural of AS - AS.s (sigh - politically correct word filtering)
03-11-2012 06:42 PM
Hi Joe,
IBGP is usually is used within an autonomous system. It is basically Internal BGP vs EBGP is used for one autonomous system to connect to another autonomous system (External BGP).
http://www.skullbox.net/bgp.php
HTH
03-12-2012 12:59 AM
Hi Joe,
Each other are there for different aspects.
iBGP is to serve within AS where eBGP is to serve between different autonomous system.
If an AS has multiple BGP speakers, the AS can serve as a transit service for other ASs.
Please rate the helpfull posts.
Regards,
Naidu.
03-12-2012 02:50 AM
Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
Joe Lee wrote:
Understand how iBGP and eBGP work, can anyone tell me what are the pros and cons between these protocols? Any documentation is greatly appriciated.
If you understand how both work, then you realize the determinant is whether to BGP peers are using the same AS or a different AS. For routine eBGP, you're peers are very likely to use different ASs, so you wouldn't have a choice. For internal BGP usage, I suppose you could use different (private?) ASs, down to individual BGP peers allowing them to operate with eBGP rules.
The pros and cons of using eBGP internally vs. iBGP would be due to the differences in peering rules and routing rules. With eBGP rules you don't need to create a full mesh as you do with iBGP (or reflectors or confederations). With eBGP rules, you're less likely to require another IGP if the peers share a common subnet, or if they don't, need special multi-hop configuration along with extra routing information external to BGP itself. With eBGP rules, AS hops might indicate actual best path.
Although in theory I guess you could use eBGP rules with private ASs within the same logical AS, it could make it difficult to peer with more then one external public AS. In other words, this isn't normally a choice, so curious how you envisioned using pros and cons to select between eBGP vs. iBGP.
PS:
NB: "***" = Plural of AS - AS.s (sigh - politically correct word filtering)
03-12-2012 05:57 AM
Hi,
Understand how iBGP and eBGP work, can anyone tell me what are the pros and cons between these protocols?
there is only one protocol in fact - BGP.
There are just eBGP and iBGP neigbors.
And different rules how prefixes received from eBGP/iBGP are treated and sent to other neighbors.
See
for examples.
HTH,
Milan
08-23-2016 10:06 AM
4 years old - WOW
Is there a different site people are going to now?
Oh yeah - I agree with Milan.
08-24-2016 01:49 AM
Postings on this site go back much further than even 4 years; mine go back to 2007, some other still active posters go back several years further.
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