Subject: [Idr] BGP maximum message size

From: suketu soni <[email-masked]>
Date: Mon, 25 Feb 2013 11:19:08 +0000

Hi Team, RFC 4271 comments about BGP maximum message size:  "BGP messages are sent over TCP connections. A message is processed only after it is entirely received. The maximum message size is 4096 octets. All implementations are required to support this maximum message size. The smallest message that may be sent consists of a BGP header without a data portion (19 octets)." Does this message size - 4096 octets - relate to maximum TCP window size used by BGP? If yes, can a BGP session's throughput be calculated (theoritical) as per the following formula? [(maximum window size of 4096 octets) x (8 bits per octet) x 1000] / (round-trip-delay in milli-second)Thanking you in advance. Best wishes

Suketu Soni

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From: Nick Hilliard <[email-masked]>
Date: Mon, 25 Feb 2013 11:33:01 +0000

On 25/02/2013 11:19, suketu soni wrote:
> Does this message size - 4096 octets - relate to maximum TCP window size
> used by BGP?

No.  it's the size of the bgp message as defined in 4271.  E.g. UPDATE +
NLRIs + attributes, etc.  It's not particularly related to tcp packet size.

Nick

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From: Tony Li <[email-masked]>
Date: Mon, 25 Feb 2013 03:37:24 -0800

> 
> RFC 4271 comments about BGP maximum message size: 
>  
> "BGP messages are sent over TCP connections. A message is processed only after it is entirely received. The maximum message size is 4096 octets. All implementations are required to support this maximum message size. The smallest message that may be sent consists of a BGP header without a data portion (19 octets)."
>  
> Does this message size - 4096 octets - relate to maximum TCP window size used by BGP?

Hi Suketu,

No, not at all.  They are completely independent.

Tony