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New Member

BGP ASN 32 bits on IOS 12.4(24)T

Hello guys, I'm trying to establish a BGP neighborship with my ISP using my own ASN. The thing is that AS is a 32bit AS. I read on others papers that since the IOS 12.4(24) the support for ASN 4byte(32bits) was introduced. For some reason I cant enable BGP under an AS32bits on my 2811.

Please, could someone advise?

Cisco IOS Software, 2800 Software (C2800NM-ADVIPSERVICESK9-M), Version 12.4(24)T1, RELEASE SOFTWARE (fc3)

BGP-AS32(config)#router bgp ?   

  <1-65535>    Autonomous system number   --> Only 16bits

  <1.0-XX.YY>  4 Octets Autonomous system number

BGP-AS32(config)#router bgp 262477

                                                     ^

% Invalid input detected at '^' marker

Thanks in advance.

Victor

  • WAN Routing and Switching
Everyone's tags (3)
1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Silver

Re: BGP ASN 32 bits on IOS 12.4(24)T

Hello Victor,

the router expects you to enter the 32 bit AS number in as dot notation that is a format with a dot in the middle between two 16 bit entities

see this example

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080bc7d00.shtml

and

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6599/data_sheet_C78-521821.html?referring_site=bodynav

notice the point in the online help

<1.0-XX.YY>  4 Octets Autonomous system number

you need to convert your AS in plain text format in as dot format by dividing for 65536 the total number  so that 65536 = 1.0 see the first example

Hope to help

Giuseppe

6 REPLIES
Hall of Fame Super Silver

Re: BGP ASN 32 bits on IOS 12.4(24)T

Hello Victor,

the router expects you to enter the 32 bit AS number in as dot notation that is a format with a dot in the middle between two 16 bit entities

see this example

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080bc7d00.shtml

and

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6599/data_sheet_C78-521821.html?referring_site=bodynav

notice the point in the online help

<1.0-XX.YY>  4 Octets Autonomous system number

you need to convert your AS in plain text format in as dot format by dividing for 65536 the total number  so that 65536 = 1.0 see the first example

Hope to help

Giuseppe

New Member

BGP ASN 32 bits on IOS 12.4(24)T

Hello Giuseppe, thank you very much for your quickly reply. So if I understand, I need to divide my ASN for 65536, this will give a number formated as dot decimal, right?

Well I've done this and got to this number 

My AS  / 65536  ==> 242677/65536 = 4,005081176757813

Should I enable bgp under the 4.0 ASN ? Like this:

router bgp 4.0

In the first example, there is a line that tells me to input the bgp asnotation dot command, but I do not have this option. Take a look:

BGP-AS32#sh run | sec bgp

router bgp 4.0

no synchronization

bgp router-id 1.1.1.1

bgp log-neighbor-changes

no auto-summary

BGP-AS32(config-router)#bgp asnotation dot

                                              ^

% Invalid input detected at '^' marker.      

BGP-AS32(config-router)#bgp a?

always-compare-med

Thanks again!

Victor

New Member

BGP ASN 32 bits on IOS 12.4(24)T

Dear Victor,

Your 4 byte ASN in ASDOT

AS in PLAIN :242677

Converted ASN: 4.333

Source : http://submit.apnic.net/cgi-bin/convert-asn.pl

HTH.

New Member

BGP ASN 32 bits on IOS 12.4(24)T

Dear dc-csa-blr, thank your for that link! It's really useful. Although I still have problems in this matter, since the document that Giusep suggested states that if you don't turn on the bgp asnotation dot option the router will assume that this is a plain notation (default).

(e.g.)

!--- This command change the default asplain notation
to dot notation.


!--- Note that without this command the AS number will
treated as asplain notation i.e. 10.1 will
be displayed as 655361

http://www.cisco.com/en/US/tech/tk365/technologies_configuration_example09186a0080bc7d00.shtml
(...)

The problem is that I cant turn this option on.

BGP-AS32(config-router)#bgp asnotation dot

                                              ^

% Invalid input detected at '^' marker.      

BGP-AS32(config-router)#bgp a?

always-compare-med

Thanks,

Victor

Hall of Fame Super Silver

Re: BGP ASN 32 bits on IOS 12.4(24)T

Hello Victor,

you have to enter the AS number as 4.333 according to the calculation performed by dc-csa-bir

router bgp 4.333

your IOS works only in as not notation ( my guess) so there is no command to enable it as it is already enabled

the online help of your router says it expect 4 byte AS in dot notation follow it.

Hope to help

Giuseppe

New Member

BGP ASN 32 bits on IOS 12.4(24)T

Thanks Giuseppe and dc-csa-blr for your replies, I really appreciate! You guys helped a lot!  5 stars each .

Victor

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