Re: BGP to OSPF Redistribution w/ Sham-Link

Actually... none of it is vrf-lite and there's no magic. For two-site
configuration, I don't see the need for redistribution. If the
sham-links wouldn't come up after a reload or a similar event, means
someone missed a crucial (undocumented) step of needing to make sure
those addresses are not advertised in OSPF. We've beaten that subject
to a pulp few years back and on average every two-three months since.
I'm kinda tired of discussing sham-links.

--
Marko Milivojevic - CCIE #18427 (SP R&S)
Senior Technical Instructor - IPexpert
On Tue, Oct 11, 2011 at 14:41, Carlos G Mendioroz <tron_at_huapi.ba.ar> wrote:
> I would be careful.
> I've just seen a test case where the sham link will not come up
> without distributing BGP into OSPF. If you still have your lab setup,
> do a full reload and check if it comes back up.
> (sham link endpoints where /32 loopbacks, advertized by BGP inside vrf)
>
> Even though sham links behave like a "standard" point to point unnumbered
> link inside the area x, there is nothing "standard" in them,
> and plenty of MPLS magic, partially controlled by vrf-lite capability.
>
> -Carlos
>
> Yuri Bank @ 11/10/2011 15:53 -0300 dixit:
>>
>> Yeah it works fine without redistributing BGP into OSPF.
>>
>> My theory is that because the Sham-Link is up, LSAs are flooded and reach
>> the CE without any problems.
>>
>> However, all of the labs, documentation etc show otherwise (redistribution
>> of BGP into OSPF), which simply isn't necessary in my opinion. I'm just
>> curious if anyone else has noticed this? Of course, if you aren't using a
>> sham-link, redistribution of BGP into OSPF is necessary.
>>
>> -Yuri
>>
>> On Tue, Oct 11, 2011 at 11:23 AM, Marko Milivojevic
>> <markom_at_ipexpert.com>wrote:
>>
>>> What happened when you labbed it up? Did it work? :-)
>>>
>>> --
>>> Marko Milivojevic - CCIE #18427
>>> Senior Technical Instructor - IPexpert
>>>
>>> FREE CCIE training: http://bit.ly/vLecture
>>>
>>> Mailto: markom_at_ipexpert.com
>>> Telephone: +1.810.326.1444
>>> Web: http://www.ipexpert.com/
>>>
>>> On Tue, Oct 11, 2011 at 11:09, Yuri Bank <yuribank_at_gmail.com> wrote:
>>>>
>>>> I'm curious if this is really necessary? I've done this in my lab and it
>>>> seems to work fine. I understand that you MUST redistribute OSPF into
>>>> BGP
>>>
>>> on
>>>>
>>>> your PE, so that appropriate VPN labels are advertised to the remote PE.
>>>> However, I see no reason to redistribute BGP into OSPF, since the LSAs
>>>
>>> are
>>>>
>>>> getting advertised through the sham-link, and the CE routers will have a
>>>> complete LinkState Database from that.
>>>>
>>>> Is there anything that I'm missing?
>>>>
>>>> -Yuri
>>>>
>>>>
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>>
>
> --
> Carlos G Mendioroz B <tron_at_huapi.ba.ar> B LW7 EQI B Argentina
>
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