The MPLS WG Archive

[ARUMUGAM R <arumugamr@future.futsoft.com>]

Hi,
Can anybody clarify the presence of  RRO Object in reroute condition.
Consider a n/w topoly given below



LER1 ---------LSR2--------LSR3--------------------------LSR4 -----------------LER5
                                              \                                           /
                                               \  LSR6 ------------LSR7 /

1.	A TE Tunnel has been established between LER1-LER5 ( LER1-LSR2-LSR3-LSR4-LER5) with ERO and RRO
 present in the PathMesg with Label Recording flag set in the SESSION ATTRIBUTE object.
 The Resv mesg is sent  from LER4 with RRO  and Label subobject.

2.  Now a reroute TE Tunnel is established  from LER1-LER5  (LER1-LSR2-LSR3-LSR6-LSR7-LSR4-LER5) with the 
same set of parameters like ERO, RRO and Label Recording Flag set.
When the resv megs arrives LSR2 , the LSR2 has to sent a combined resv message since the PHOP 
does not change.
Whether the resv message format looks like this.

<FLOWSPEC><old_FILTER_SPEC><old_LABEL_OBJECT>[<old_RRO>]
                         <new_FILTER_SPEC><new_LABEL_OBJECT><new_RRO> --- (1)

or

<FLOWSPEC><old_FILTER_SPEC><old_LABEL_OBJECT>
                         <new_FILTER_SPEC><new_LABEL_OBJECT><new_RRO> ---- (2)

If the format is like (2) then suppose  by inclusion of new_RRO , if the MTU size exceeds,
LSR3 sends ResvErr to LER5 and forwards the ResvMesg  without RRO ( Ref -Section 4.5). 
LSR2 on receiving this Resv mesg since the old_RRO is not present, for the old_FILTER_SPEC,old_LABEL_OBJECT
combination whether it has to remove the old_RRO considering it has been removed by the new ResvMesg or it has to
 retain the information while refresing the Resv message.

Thanks in advance
Regards
Aru
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Arumugam R
Senior Software Engineer,
Future Software Pvt Ltd.
Chennai - 35
Fone-4330550 Extn-332
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