Re: Internet routing table

Hi Roy,

This may be useful for a route reflectors - they normally don't
advertise themselves as next-hops (iBGP). The advantage is that we don't
build RIB, FIB, LFIB for SW platforms and don't utilize TCAMs for HW
platforms, eg. c7600 with non XL supervisor that is not anymore able to
store full Internet routing table.
It is similar also to "no bgp default route-target filter" for vpnv4,
when given route target is not imported to any local VRF but we have to
relay routes toward neighbors (for whatever reason).

Cheers,
Tomasz.

Roy Waterman pisze:
> Hi Jason I must be missing something here.
> You mention:
>
> by adjusting the admin distance of the BGP routes to 255 , so that it will
> not be installed in the routing table , but you still have it in the BGP
> table so that you can send these routes to any downstream neighbor
>
> However, if the bgp routes are not installed in the local routing table,
> what is the reason for receiving them?
> Say you receive an advertisement eg 20.0.0.0/8, which you change the AD to
> 255.
> Sure your downstream neighbors on the same LAN will route traffic to
> 20.0.0.0/8 to you, but what do YOU do once you receive such packets?
> After all, with no route for 20.0.0.0/8 in the routing table, and if you
> have no default route pointing to the upstream nei, you will simply drop
> such packets.
>
> Is the addition of the default route in relation to the AD of 255 what you
> were thinking?
> I'm also wondering about why you would have such a ... design like this.
>
> Please clarify.
>
>
> 2009/4/21 Jason Alex <amr.ccie_at_gmail.com>
>
>
>> You can have another option , go for WS-SUP720-3B and get the full Internet
>> routing table on the BGP table only not on the routing table unless you
>> need
>> all the full Internet table inside your routing table
>>
>> by adjusting the admin distance of the BGP routes to 255 , so that it will
>> not be installed in the routing table , but you still have it in the BGP
>> table so that you can send these routes to any downstream neighbor
>>
>> HTH
>>
>> Regards
>>
>> On Tue, Apr 21, 2009 at 8:33 AM, Scott Morris <
>> smorris_at_internetworkexpert.com> wrote:
>>
>>
>>> There are roughly 287,000 routes in the full BGP table at this moment...
>>>
>>> Your choice, but I'd go for the XL.
>>>
>>> Scott
>>>
>>>
>>>
>>> Sharma, Praveen wrote:
>>>
>>>
>>>> Hi CS,
>>>>
>>>>
>>>>
>>>> I am looking for deploying internet router, I have two options here
>>>>
>>>>
>>>>
>>>> WS-SUP720-3B it support 256000 IPv4 routes
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> WS-SUP720-3BXL it support 1,000,000 Ipv4 routes.
>>>>
>>>>
>>>>
>>>> I my design I will be having dual internet from different providers on
>>>> two physical routers, my question I can have SUP-720-3B and still have
>>>> full internet routing table in it.
>>>>
>>>>
>>>>
>>>> Thanks
>>>>
>>>> Praveen
>>>>
>>>>
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Received on Tue Apr 21 2009 - 11:42:33 ART