PBBTE Requirements

1
PBB-TE Requirements
22.January 2007

• bsultan_at_huawei.com
• ldunbar_at_huawei.com

2
Problem Simple partition of BVID space
Non-sequential PBB BVID assignments
BVID assignments for simply partitioned PBB/PBB-TE

• Assume
• BVIDs not assigned sequentially for PBB
• PBB-TE allows only simple partition of BVID
  space
• BVID lt N ? PBB
• BVID N ? PBB-TE
• Observe
• Migration requires reassignment of many PBB BVIDs

PBB-TE 2000
PBB lt 2000
3
Remedy Distinct assignment per BVID
Non-sequential PBB BVID assignments
Non-disruptively adding PBB-TE BVID assignments

• Conclusions
• Simple partition of BVID space is insufficient
• Individual assignment of BVIDs is needed
• Statement of requirement
• The introduction of TE in a PBBN should not
  require reassignment of BVID values currently
  used for PBB traffic.
• It is an option to allow a simple partition of
  the space when PBB reassignment is not a concern.

4
Option to eliminate need to partition BVID space
PBB BVID assignments
PBB-TE BVID assignments

• Distinguish PBB vs. PBB-TE traffic by Ethertype
• or other convenient marking.
• guarantee that PBB forwarding cannot interfere
  with PBB-TE forwarding
• greatly simplifies PBB / PBB-TE BVID assignment
• Understood that BCB (PB) need additional function
  to interpret both Ethertypes.
• Considering that PBB-TE requires all BCB(PB)
  nodes to change forwarding behavior anyway, it is
  not too much additional function.

5
Problem PBB traffic interferes with PBB-TE
traffic

• PBB-TE is provisioned along path and policed at
  ingress edge (no problem)
• PBB paths are not provisioned
• Difficult to know appropriate rate for edge
  policing
• Must give PBB-TE traffic absolute priority over
  PBB traffic
• Not possible if PBB already using highest
  priority value
• Distinct PRI spaces provides natural solution
• PBB and PBB-TE can each use full set of priority
  values
• PBB-TE always granted absolute priority over PBB

PBB-TE (red) traffic granted absolute priority
over PBB (blue) traffic.
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Requirements

• Base is to allow any BVID to be assigned PBB or
  PBB-TE
• Option is to allow a partition between PBB and
  PBB-TE BVIDs.
• Option for differential treatment (e.g., by
  Ethertype) of PBB and PBB-TE
• Avoid BVID and/or PRI reassignment on migration
• Ethertype is reasonable way to provide this
  option

7
Additional benefit of using EtherType to
differentiate PBB-TE traffic and PBB traff
8
Provisioning Error at Switch H
E
Backbone Edge Bridge (BEB) IEEE 802.1ah
B
4
Backbone Core Bridge (BEB) IEEE 802.1ad
A
F
G
Backbone Spanning Tree
Red transport traffic (on backbone VID 10)
Blue transport traffic (on backbone VID 10)
3
2
H
I
Red transport not provisioned (by error)
1
BVID10 correctly provisioned for transport
BVID10 incorrectly provisioned for bridging

• Switch H has been incorrectly provisioned so that
• backbone VLAN ID (BVID) 10 is associated with
  bridging instead of transport
• provisioning of the red transport has been
  omitted.

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Impact of PBT Configuration Error

• Frame enters the red transport at I.
• Frame correctly forwarded from I to H via red
  transport.
• Frame flooded from H to B and from H to F via
  Spanning Tree due to provisioning errors at H.
• Frame is erroneously forwarded from B to A via
  blue transport.
• Consequence is that capacity on link B-A,
  committed to the blue transport, is consumed by
  the red transport. The red transport is denied
  the level of service for which it has contracted.