oh, sorry, I meant "1. the node will not process the TLV if the length of TLV 
is NOT longer that (0+1)*2. ", sorry for missing the important word.

From: Huzhibo
Sent: Wednesday, June 29, 2022 9:10 AM
To: 'spring@ietf.org' <spring@ietf.org>
Subject: Question of SRH.Last_entry=0 in Reduced mode

Hi SPRING,

I have a simple question: Do we allow to have empty Segment list in SRH?   For 
instance, only carry common SRH header(8 Bytes) or carry the Common header with 
option TLV without any SID.

According to the definition of RFC8754[1], "TLVs are present when the Hdr Ext 
Len is greater than (Last Entry+1)*2".

In reduced mode, if we only have one single SRv6 SID or one single CSID 
container, the single SRv6 SID/CSID container will be put in the DA and no SID 
will be carried in the SRH.

In this case, we will meet some errors:

1.       the node will not process the TLV if the length of TLV is longer that 
(0+1)*2.

2.       the node cannot locate the correct beginning of the TLV because no 
matter 1 SID or 0 SID in the SRH, the last entry will be 0 in both cases.

We may suggest to disable reduced mode and encode the SID in the SRH when only 
one SID/CSID container in the SRH, so that the node can process the TLV(HMAC, 
etc.) correctly.

Thoughts?

Zhibo

[1]. https://datatracker.ietf.org/doc/html/rfc8754#section-2

_______________________________________________
spring mailing list
spring@ietf.org
https://www.ietf.org/mailman/listinfo/spring

Reply via email to