Redundancy SID and Merging SID for
Redundancy ProtectionHuaweigengxuesong@huawei.comHuaweimach.chen@huawei.comRedundancy protection is a method of service protection by sending
copies of the same packets of one flow over multiple paths, which
includes packet replication, elimination and ordering. This document
defines Redundancy SID and Merging SID to support redundancy
protection.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in .Redundancy protection is a method of providing 1+1 protection by
sending copies of the same packets of one flow over multiple paths,
which includes packet replication, elimination and ordering. This
document defines Redundancy SID and Merging SID to support redundancy
protection.The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in .Redundancy Node: the start point of redundancy protection, which is a
network device that could implement packet replication.Merging Node: the end point of redundancy protection, which is a
network node that could implement packet elimination and ordering
(optionally).Editor's Note: Similar mechanism is defined as "Service Protection"
in the . In this document, we define a new term
"Redundancy Protection" to distinguish with other service protection
method. Some of the terms are the similar as .The figure shows how to provide redundancy protection in an Segment
Routing Domain.|
| |
| +------+T2+----+ |
+---+ +---+ +-+-+ +-+-+ +---+ +---+
| E1+----| In|--+T1+--+Red| |Mer|--+T4+--| Eg+----+ E2|
+---+ +---+ +-+-+ +-+-+ +---+ +---+
+-----+T3+-----+
]]>The process of redundancy protection is as follows: 1) The flow is
replicated in Red(Redundancy Node); 2) Tow replicated flows go through
different paths till Mer (Merging Node); When there is any failures
happened in one the path, the service continues to deliver through the
other path without break; 3) The first received packet of the flow is
transmitted from Mer (Merging Node) to Eg(Egress), and the redundant
packets are eliminated. 4) Sometimes, the packet will arrive out of
order because of redundancy protection, the function of reordering may
be necessary in the Merging Node.In this document, we introduces Redundancy SID and Merging SID to
implement redundancy protection. The newly defined SIDs apply equally to
both SR-MPLS and SRv6.Redundancy SID is a variation of binding SID defined in Redundancy SID indicates the following operations:Steering the packet into the corresponding redundancy policyPacket replication based on the redundancy policy, e.g., the
number of replication copiesEncapsulate the packet with necessary meta data (e.g., flow
identification, sequence number) if it is not included in the
original packetMerging SID indicates the following operations:Packet elimination: forward the first received packets and
eliminate the redundant packets.Packet ordering(optional): reorder the packets if the packet
arrives out of orderTBDTBDThank you for valuable comments from James Guichard and Andrew
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