Re: [Idr] Can one Destination Address appear in both Tunnel Encap Attribute and in MP_REACH_NLRI ?

[Robert Raszuk <[e-mail]>]

Hi Linda,

Yes your interpretation is correct.

Thx
R.

On Tue, Oct 22, 2019, 16:25 Linda Dunbar <[e-mail]> wrote:

> Srihari and Robert,
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> Thank you very much for the discussion.
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> Your explanation indicates that the tunnel information described in Tunnel
> Path Attributes are applicable to all the NLRI listed in the MP-NLRI Path
> Attributes, correct?
>
> For example, D1/D2/D3/D4 all have R2 as Next Hop, and R2 supports GRE and
> VxLAN.  The Update from R2 will have D1, D2, D3, D4 listed in the MP-NLRI
> (code= 14), and GRE tunnel & VxLAN tunnel listed under the Tunnel Attribute
> (code = 23).
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> When R1 receives the UPDATE from R2, R1 can assume that packets to D1, D2,
> D3, D4 can use either VxLAN or GRE. Is it correct?
>
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> So if R2 needs to specifically indicate GRE for D1, VxLAN for D2, D3, and
> IPinIP for D4, then R2 needs to send 3 separate UPDATE messages. Is it
> correct?
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> Thank you very much.
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> *From:* Srihari Sangli <[e-mail]>
> *Sent:* Thursday, October 17, 2019 3:08 AM
> *To:* Robert Raszuk <[e-mail]>; Srihari Sangli <ssangli=
> [e-mail]>
> *Cc:* Linda Dunbar <[e-mail]>; [e-mail];
> [e-mail]
> *Subject:* Re: [Idr] Can one Destination Address appear in both Tunnel
> Encap Attribute and in MP_REACH_NLRI ?
>
>
>
> Hi Robert,
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> My reading of Linda's point was a question regarding the case where for
> prefix A NLRI points to
>
> next hop NH_1 but tunnel endpoint says go to NH_2.
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> Is such update still valid ?
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> Has tunnel encapsulation attribute power to "overrule" BGP next hop from
> MP_REACH ?
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> The draft in Section 5 explains this. If the update has a valid Tunnel
> Encapsulation attribute and if any of the tunnel(s) is considered to be
> feasible, then it MUST use the tunnel. That means in your example, such an
> update is valid and NH_2 should be used.
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> Hope this helps. Thanks.
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> srihari…
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