Re: [Softwires] PSID format as described in rfc 7597 vs. rfc 7598

otroan@employees.org Tue, 26 July 2016 08:50 UTC

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From: otroan@employees.org
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Date: Tue, 26 Jul 2016 10:50:26 +0200
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To: yannis nikolopoulos <yanodd@otenet.gr>
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Subject: Re: [Softwires] PSID format as described in rfc 7597 vs. rfc 7598
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Yannis,

>>>> 2, What's the reason for the difference in the formats?
>>> 
>>> Good question. The 7597 PSID in the IID is mainly there for pretty printing / troubleshooting, and it makes sense to left pad it.
>>> I can only guess about the 7598 format, possibly to keep the PSID field consistent with the other fields (prefix) which are all right padded.
>> 
> 
> this might create some confusion about the way the lwB4 will construct the IID for the tunnel endpoint (use "2" or "800" for the last 16 bits?)

it shouldn't. in 7596 it states that the IID is created as specified in 7597.
that 7598 uses a different on-the-wire format doesn't change that.
in MAP data packets those bits are again represented in a different bit position.

>> I agree with Ole. For your information, our implementation has a configuration function to select the format of PSID. Regards, xing
> 
> where is this function implemented?

I don't know, but just a point to the IID generation, it must be a consistent method used across the domain (in algorithmic mapping), but in LW46 it could pretty much be anything you like, if you have a way to coordinate that between the BR and CEs.

Best regards,
Ole