GMPLS constraints consideration
for CSPF path computation
draft-otani-ccamp-gmpls-cspf-constraints-00.txt
Tomohiro Otani otani@kddilabs.jp
Kenichi Ogaki ogaki@kddilabs.jp
Arthi Ayyangar arthi@juniper.net
62st IETF Minneapolis, March. 2005
Summary of this BCP draft
• This draft fits to the following charter item
– “Definition of the mechanisms required to determine
the route and properties of an established path (tunnel
tracing)”.
• This draft
– states the problem of GMPLS CSPF path computation
• Since these attributes are differently understood in an industrial
environment (especially between optical and packet transport
point of view), the path computation results sometimes vary.
– tries to provide the guideline to consider GMPLS TE
attributes for CSFP path computation at a source node.
• TE attributes must be dealt with correctly in the case of CSPF
path computation considering underlying physical and logical
technologies of nodes as well as links.
62st IETF Minneapolis, March. 2005
Considered network model
Ingress
Transit
Egress
+-----+ Enc.:enc^in
+-----+ Enc.:enc^tr
+-----+
|
|<---------//--------->|
|<---------//--------->|
|
|SC: |
Enc.: enc^tr |SC: |
Enc.: enc^eg |SC: |
|sc^in| BW:bw^in
|sc^tr| BW:bw^tr
|sc_eg|
|
|<---------//--------->|
|<---------//--------->|
|
+-----+
BW: bw^tr +-----+
BW: bw^eg +-----+
• To correctly establish a GMPLS LSP from an ingress to an egress, a
possible combination of GMPLS attributes is investigated.
• Assumption for the simplicity
– Switching capability (SC) must be consistent from an ingress node to an
egress node [smaller switching granularity at ingress/egress nodes].
– Switching capability of transit nodes must be consistent with switching
capability of a LSP to be created (not multi-layer).
– Encoding-type must be consistent along a route to be established.
62st IETF Minneapolis, March. 2005
CSPF consideration (example)
(2) Lambda switch capable (LSC) at transiting nodes
+-----+---------+---------+---------+---------+-------------------+
|Case |LSP
|Ingress |Transit |Egress
|Remarks
|
+-----+---------+---------+---------+---------+-------------------+
| |SC |lambda
|<=lambda |lambda
|<=lambda |gmpls-routing-09
|
|1|Enc|lambda
|lambda
|lambda
|lambda
|section 3.7, 3.10 |
| |BW |X
|<=bw^so |<=bw^tr |<=bw^en |
|
+-----+---------+---------+---------+---------+-------------------+
| |SC |lambda
|<=lambda |lambda
|<=lambda |gmpls-routing-09
|
|2|Enc|SONET/SDH|SONET/SDH|SONET/SDH|SONET/SDH|section 3.6, 3.9
|
| |BW |X
|=bw^so
|=bw^tr
|=bw^en
|Specified in G.691 |
+-----+---------+---------+---------+---------+-------------------+
| |SC |lambda
|<=lambda |lambda
|<=lambda |
|
|3|Enc|Etherner |Ethernet |Ethernet |Ethernet |
|
| |BW |X
|=bw^so
|=bw^tr
|=bw^en
|Specified in IEEE |
+-----+---------+---------+---------+---------+-------------------+
| |SC |lambda
|<=lambda |lambda
|<=lambda |
|
|4|Enc|OTN
|OTN
|OTN
|OTN
|
|
| |BW |X
|=bw^so
|=bw^tr
|=bw^en
|Specified in G.709 |
+-----+---------+---------+---------+---------+-------------------+
The LSP to be created
from an ingress
GMPLS attributes to be
satisfied in CSPF calculation
(<=lambda means psc/L2SW/TDM/Lambda)
62st IETF Minneapolis, March. 2005
Next Steps
• We would like cover all possible cases to create a
concrete guideline of CSPF path computation in terms of
GMPLS attributes
– Encoding may have multiple matches, but discussion is needed.
LSP encoding
• Ethernet
• SONET-SDH
• Lambda
TE Link encoding
Ethernet, Lamda, Fiber
SONET-SDH, Lambda (true?), Fiber (true?)
Lambda, Fiber
– Especially L2SC (discussion in this meeting)
– Any feedback would be greatly appreciated.
• Will investigate multi-layer consideration.
62st IETF Minneapolis, March. 2005