Re: [mpls-tp] Query on MPLS-TP lsp ping extensions

[Mukund Mani <[e-mail]>]

Hi Nitin

Thanks for the reply....

Indeed i too thought we are referring to the IP Channel type of 0x21, but
then that means that the ACH header should be present
to indicate the control channel type. The draft does not mention that in LSP
Ping with IP encapsulation section, though it does so
specifically in the non-IP section. Why do we really need the ACH in this
case because the host stack has Ip addressing capability and the reply can
be IP addressed to the source (forwarded via MPLS labels)


Also i agree both Source Address TLV and MEP ID is not required but the
draft mentions MAY for both. Thus the confusion.
Either one is a MUST to identify the source. Maybe this can be clarified.

In the same context when i refer to Section 2.3 of the draft, it mentions
that

"When sending LSP-Ping packets using ACH, there MAY be a need to identify
the maintenance end point (MEP) and/or the maintenance intermediate point
(MIP) being monitored"

which implies that the MEP of the destination of that LSP or MIP for which
ping is sent, is being carried whereas in the Source Address TLV we carry
the Source MEP IP which initiates the operation (ping in this case).

Basically am trying to understand some scenarios as to when and why i would
have the following in my packets and what will be my processing actions in
the control plane....

1. Source Address TLV present.
2. MEP - ID of the end point/ MIP ID for which the ping request is being
sent.
3. MEP - ID of the source that initiated the ping request.



Indeed this draft does not request for a new TLV type and the text is also
clear. But I was referring to the actual
definition of the source address TLV in the draft ach-tlv. There the Source
Address TLV contains the IPv4 address iso the TP identifier format...



Regards
Mukund

On Fri, May 7, 2010 at 10:46 AM, Nitin Bahadur <[e-mail]> wrote:

>
> Hi Mukund,
>
>  See inline below to answers to your queries.
>
> On 5/6/10 12:56 PM, "Mukund Mani" <[e-mail]> wrote:
>
> Hi Nitin
>
> Wrt the draft-nitinb-mpls-tp-lsp-ping-extensions-01,  Section 3.1 refers to
> LSP Ping with IP encapsulation.
> It is mentioned that the LSP-Ping reply mode in the LSP Ping echo request
> MUST
> be set to 4 (Reply via application level control channel)
> What IP application control channels are we referring to here?
>
> NB> We are referring to the IP channel type of 0x21 (RFC 5085).
>
> Also Section 3.2 (Non-IP based LSP Ping) mentions that the
> ingress node MAY attach a Source Address TLV.
> In MPLS-TP environment wouldn't this always be required?
>
> NB> No. One can use either MEP-ID or Src-addr tlv to perform connectivity
> verification. Both are not needed and
> hence the draft does not say it’s a MUST for src-addr tlv.
>
> Irrespective, if one may use this TLV, as per the
> draft-ietf-mpls-tp-ach-tlv-02
> it contains the IPv4 address. Shouldnt we have the TP identifier format
> instead?
>
> NB> The draft is proposing to use the TLV described in ach-tlv draft. No
> new TLV is being added. If you look at the IANA section
> of this draft, there is no request for a new tlv type for src-addr-tlv.
> Section 2.2 of the draft clarifies some of this. If you feel the
> text is unclear, please propose alternative text and we can consider that.
>
> Thanks
> Nitin
>