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Published byLynette Harrison Modified over 6 years ago
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bsultan@huawei.com ldunbar@huawei.com
22.January 2007 PBB-TE Requirements
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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 < N PBB BVID ≥ N PBB-TE Observe: Migration requires reassignment of many PBB BVIDs BVID TYPE 4095 - 4094 2020 PBB 2019 2018 2017 2016 5 4 3 2 1 BVID TYPE 4095 - 4094 2020 2019 TE 2018 2017 2016 5 PBB 4 3 2 1 PBB-TE ≥ 2000 PBB < 2000 Page 2
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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. BVID TYPE 4095 - 4094 2020 PBB 2019 2018 2017 2016 5 4 3 2 1 BVID TYPE 4095 - 4094 2020 PBB 2019 2018 2017 TE 2016 5 4 3 2 1 Page 3
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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. BVID TYPE 4095 - 4094 2020 PBB 2019 2018 2017 2016 5 4 3 2 1 BVID TYPE 4095 - 4094 2020 2019 2018 2017 TE 2016 5 4 3 2 1 Page 4
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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. Page 5
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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 Page 6
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Additional benefit of using EtherType to differentiate PBB-TE traffic and PBB traff:
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Provisioning Error at Switch H
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) 3 Blue transport traffic (on backbone VID 10) 2 H I 1 Red transport not provisioned (by error) 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. Page 8
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Impact of PBT Configuration Error
Backbone Spanning Tree Red transport traffic (on backbone VID 10) Blue transport traffic (on backbone VID 10) Backbone Edge Bridge (BEB) IEEE 802.1ah Backbone Core Bridge (BEB) IEEE 802.1ad Red transport not provisioned (by error) A B E F G H I 1 2 3 4 BVID10 correctly provisioned for transport BVID10 incorrectly provisioned for bridging 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. Page 9
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