04-16-2007 08:09 AM - edited 03-03-2019 04:33 PM
Hi,
what is the maximum number of EBGP sessions supported on 18xx, 28xx and 38xx routers?
Regards
Stefano
04-16-2007 08:25 AM
Stefano
As far as I know there is not an absolute limit on the number of EBGP sessions. It is mostly a question of the resources needed for each neighbor (how many routes, etc) and the resources available on the router.
HTH
Rick
04-16-2007 08:44 AM
OK,
so if I have for example a limited amount of routes (less than 5) for each BGP neighbor, how can I compute router's resources needed for each session?
Many thanks
Stefano
04-16-2007 09:05 AM
Hi Stefano,
You can use "show ip bgp neighbor
HTH,
Mohammed Mahmoud.
04-17-2007 12:45 AM
Thank you Mohammed.
Anyway my issue is extremely practical: if I have for instance a 2851 router at headquarter site and this router has to support N x GRE tunnels to remote sites along with N x BGP neighborship, how can I determine N with a certain accuracy?
Regards
Stefano
04-17-2007 12:53 AM
Hi,
For your 2851 in HQ, you will create 1 GRE Tunnel for each Remote GRE Capable Router. Also, you will establish 1 BGP Neighborship for each Remote BGP Capable Router.
Therefore, N in GRE Tunnel is the number of Remote GRE Capable Router, while N in BGP Neighborship is the number of Remote BGP Capable Router.
I say "Capable" because not all router model and IOS support IP GRE and BGP.
04-17-2007 01:00 AM
I would like to determine the maximum 'N' supported, with N the number of remote sites connected with a GRE tunnel to HQ site and with 1 BGP neighborship with HQ router
Regards
Stefano
04-17-2007 03:07 AM
Hi Stefano,
The number of interfaces supported by a router is a function of the platform and the Cisco IOS software release, and can be tested using the "show idp"
example:
router#sh idb
Maximum number of Software IDBs 2000. In use 66.
HWIDBs SWIDBs
Active 42 61
Inactive 2 5
Total IDBs 44 66
Size each (bytes) 4648 1400
Total bytes 204512 92400
http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_tech_note09186a0080094322.shtml
The maximum number of interfaces (physical, subinterface, or virtual) a router can handle depends on the maximum number of SWIDBs that the router can use.
Each tunnel interface definition, such as Universal Transport Interface (UTI), Generic Routing Encapsulation (GRE), Multiprotocol Label Switching Traffic Engineering (MPLS TE), or Any Transport over MPLS (AToM) consumes an HWIDB plus one SWIDB per tunnel, plus an additional SWIDB for each additional sub-interface, for example, a Frame Relay PVC, that is tunneled. The tunnel IDBs are in addition to the original interface(s) that are tunneled.
HTH,
Mohammed Mahmoud.
04-17-2007 10:12 AM
Mohammed, this is great info.
Thanks.
04-17-2007 12:38 PM
Bravo!
Thumbs UP!!!
Kind Regards,
Danail Petrov
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