ieee 802.1aq control of the mac-in-mac hash/ttl b-vid(s) jan 2011 peter ashwood-smith...
TRANSCRIPT
IEEE 802.1aq
control of theMac-in-Mac Hash/TTL
B-VID(s)
Jan 2011
Peter Ashwood-Smith
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Background
• 802.1aq creates new behavior for a B-VID.• Traffic on a B-VID within an 802.1aq domain
travels shortest path towards its B-DA, very different than normal PBB use.– No learning/Output by computation– Ingress Check/Discard if incorrect
• Therefore 802.1aq has mechanisms to ensure B-VID function is agreed to within the 802.1aq domain.
• To change the function, add or delete a new B-VID 802.1aq has mechanisms to advertise and verify consistency.
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Background
• The function of a B-VID is defined with a tuple:
{ < B-VID > , <ECT-ALGORITHM> }
• The <ECT-ALGORITHM> is further broken down into a world wide unique OUI and local ‘index’.
• 802.1aq currently defines 17 values all with the 802.1 OUI. These are indexes 0..16.
• Index 0 is for a shared tree (CIST) while indexes 1..17 are for SPF trees with different tie breakers.
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Tuples are exchanged and verified
:1
:2 :3
:4
:5:6
B-VID,ECT-ALGORITHM tuplesAre exchanged in hellos and checkedfor consistency.
B-VID,ECT-ALGORITHM tuplesare also advertised in LSPs.
Inconsistency is only permitted if a tuple is not in use.
We can therefore introduce a new B-VID, ECT-ALGORITHM and temporaryinconsistency is allowed until we start using it.
We can therefore remove all services from a B-VID, ECT-ALGORITHM andthen start to delete it and inconsistency is allowed while I delete it.
Migration to a new B-VID, ECT-ALGORITHM or away from one then onlyrequires edge by edge re-provisioning, can be done over days/weeks.
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Algorithm to B-VID association in Hello
+-+-+-+-+-+-+-+-+ |Type= SPB-B-VID| = 5 +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+-------------------------------+ | ECT - VID Tuple (1) (6 bytes) | +-----------------------------------------------+ | ......................... | +-----------------------------------------------+ | ECT - VID Tuples (N) (6 bytes) | +-----------------------------------------------+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | ECT - Algorithm (32 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Base VID (12 bits) |U|M|RES| +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Algorithm to B-VID association in LSP.
+-+-+-+-+-+-+-+-+ |Type = SPB-Inst| = 1 +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CIST Root Identifier (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CIST Root Identifier (cont) (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | CIST External ROOT Path Cost (4 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Bridge Priority | (2 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R R R R R R R R R R R|V| SPSOURCEID | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Num of Trees | (1 bytes) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | VLAN-ID (1) Tuples (8 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | VLAN-ID (N) Tuples (8 bytes) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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TLV – SPB-Service Instance
+-+-+-+-+-+-+-+-+ |Type = SPBM-SI | = 3 +-+-+-+-+-+-+-+-+ | Length | (1 byte) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | B-MAC ADDRESS | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | B-MAC ADDRESS (6 bytes) | Res. | Base-VID (12 bits) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |T|R| Reserved | ISID #1 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |T|R| Reserved | ISID #2 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |T|R| Reserved | ISID #n | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
A service is assigned to an ALGORITHM indirectly through associationwith a Base-VID. The Base-VID of course is part of an ALGORITH,VIDtuple.
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Suggested approach for ECMP
• Assuming an 802.1aq network running some number of ECT-ALGORITHMS.
• A new B-VID, ECT-ALGORITHM tuple is assigned and advertised normally.
• The new B-VID, ECT-ALGORITHM would cause hash based forwarding/TTL decrement for UNICAST traffic only.
• Migration to/from this B-VID would be identical to any other B-VID running an AQ forwarding plane.
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Possible ECMP encodings
ECT-ALGORITHM UCAST BEHAVIOR MCAST BEHAVIOR00-80-C2-00 CIST CIST
00-80-C2-01 SPF low path id SPF low path id
00-80-C2-02 SPF low mask 0xFF SPF low mask 0xFF
…. … …
00-80-C2-10 SPF low mask 0xEE SPF low mask 0xEE
00-80-C2-11 ECMP hash alg#1 SPF low path id
00-80-C2-12 ECMP hash alg#1 SPF low mask 0xFF
… … …
00-80-C2-20 ECMP hash alg#1 SPF low mask 0xEE
00-80-C2-21 ECMP hash alg#2 SPF low path id
00-80-C2-22 ECMP hash alg#2 SPF low mask 0xFF
… … …
00-80-C2-30 ECMP hash alg#2 SPF low mask 0xEE
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