From d4a70647e6b8de2cb81cbea3c53d08c299b65cc5 Mon Sep 17 00:00:00 2001 From: Nathan Skrzypczak Date: Fri, 8 Oct 2021 14:01:27 +0200 Subject: docs: convert vpp doc md->rst Type: improvement Change-Id: If453321785b04f9c16e8cea36fb1910efaeb2c59 Signed-off-by: Nathan Skrzypczak --- src/vnet/srmpls/sr_doc.md | 121 ---------------------------------------------- 1 file changed, 121 deletions(-) delete mode 100644 src/vnet/srmpls/sr_doc.md (limited to 'src/vnet/srmpls/sr_doc.md') diff --git a/src/vnet/srmpls/sr_doc.md b/src/vnet/srmpls/sr_doc.md deleted file mode 100644 index 29110ec8c41..00000000000 --- a/src/vnet/srmpls/sr_doc.md +++ /dev/null @@ -1,121 +0,0 @@ -# SR-MPLS: Segment Routing for MPLS {#srmpls_doc} - -This is a memo intended to contain documentation of the VPP SR-MPLS implementation. -Everything that is not directly obvious should come here. -For any feedback on content that should be explained please mailto:pcamaril@cisco.com - -## Segment Routing - -Segment routing is a network technology focused on addressing the limitations of existing IP and Multiprotocol Label Switching (MPLS) networks in terms of simplicity, scale, and ease of operation. It is a foundation for application engineered routing as it prepares the networks for new business models where applications can control the network behavior. - -Segment routing seeks the right balance between distributed intelligence and centralized optimization and programming. It was built for the software-defined networking (SDN) era. - -Segment routing enhances packet forwarding behavior by enabling a network to transport unicast packets through a specific forwarding path, different from the normal path that a packet usually takes (IGP shortest path or BGP best path). This capability benefits many use cases, and one can build those specific paths based on application requirements. - -Segment routing uses the source routing paradigm. A node, usually a router but also a switch, a trusted server, or a virtual forwarder running on a hypervisor, steers a packet through an ordered list of instructions, called segments. A segment can represent any instruction, topological or service-based. A segment can have a local semantic to a segment-routing node or global within a segment-routing network. Segment routing allows an operator to enforce a flow through any topological path and service chain while maintaining per-flow state only at the ingress node to the segment-routing network. Segment routing also supports equal-cost multipath (ECMP) by design. - -Segment routing can operate with either an MPLS or an IPv6 data plane. All the currently available MPLS services, such as Layer 3 VPN (L3VPN), L2VPN (Virtual Private Wire Service [VPWS], Virtual Private LAN Services [VPLS], Ethernet VPN [E-VPN], and Provider Backbone Bridging Ethernet VPN [PBB-EVPN]), can run on top of a segment-routing transport network. - -**The implementation of Segment Routing in VPP covers both the IPv6 data plane (SRv6) as well as the MPLS data plane (SR-MPLS). This page contains the SR-MPLS documentation.** - -## Segment Routing terminology - -* SegmentID (SID): is an MPLS label. -* Segment List (SL) (SID List): is the sequence of SIDs that the packet will traverse. -* SR Policy: is a set of candidate paths (SID list+weight). An SR policy is uniquely identified by its Binding SID and associated with a weighted set of Segment Lists. In case several SID lists are defined, traffic steered into the policy is unevenly load-balanced among them according to their respective weights. -* BindingSID: a BindingSID is a SID (only one) associated one-one with an SR Policy. If a packet arrives with MPLS label corresponding to a BindingSID, then the SR policy will be applied to such packet. (BindingSID is popped first.) - -## SR-MPLS features in VPP - -The SR-MPLS implementation is focused on the SR policies, as well on its steering. Others SR-MPLS features, such as for example AdjSIDs, can be achieved using the regular VPP MPLS implementation. - -The Segment Routing Policy (*draft-filsfils-spring-segment-routing-policy*) defines SR Policies. - -## Creating a SR Policy - -An SR Policy is defined by a Binding SID and a weighted set of Segment Lists. - -A new SR policy is created with a first SID list using: - - sr mpls policy add bsid 40001 next 16001 next 16002 next 16003 (weight 5) - -* The weight parameter is only used if more than one SID list is associated with the policy. - -An SR policy is deleted with: - - sr mpls policy del bsid 40001 - -The existing SR policies are listed with: - - show sr mpls policies - -### Adding/Removing SID Lists from an SR policy - -An additional SID list is associated with an existing SR policy with: - - sr mpls policy mod bsid 40001 add sl next 16001 next 16002 next 16003 (weight 3) - -Conversely, a SID list can be removed from an SR policy with: - - sr mpls policy mod bsid 4001 del sl index 1 - -Note that this CLI cannot be used to remove the last SID list of a policy. Instead the SR policy delete CLI must be used. - -The weight of a SID list can also be modified with: - - sr mpls policy mod bsid 40001 mod sl index 1 weight 4 - -### SR Policies: Spray policies - -Spray policies are a specific type of SR policies where the packet is replicated on all the SID lists, rather than load-balanced among them. - -SID list weights are ignored with this type of policies. - -A Spray policy is instantiated by appending the keyword **spray** to a regular SR-MPLS policy command, as in: - - sr mpls policy add bsid 40002 next 16001 next 16002 next 16003 spray - -Spray policies are used for removing multicast state from a network core domain, and instead send a linear unicast copy to every access node. The last SID in each list accesses the multicast tree within the access node. - -## Steering packets into a SR Policy - -Segment Routing supports three methos of steering traffic into an SR policy. - -### Local steering - -In this variant incoming packets match a routing policy which directs them on a local SR policy. - -In order to achieve this behavior the user needs to create an 'sr steering policy via sr policy bsid'. - - sr mpls steer l3 2001::/64 via sr policy bsid 40001 - sr mpls steer l3 2001::/64 via sr policy bsid 40001 fib-table 3 - sr mpls steer l3 10.0.0.0/16 via sr policy bsid 40001 - sr mpls steer l3 10.0.0.0/16 via sr policy bsid 40001 vpn-label 500 - -### Remote steering - -In this variant incoming packets have an active SID matching a local BSID at the head-end. - -In order to achieve this behavior the packets should simply arrive with an active SID equal to the Binding SID of a locally instantiated SR policy. - -### Automated steering - -In this variant incoming packets match a BGP/Service route which recurses on the BSID of a local policy. - -In order to achieve this behavior the user first needs to color the SR policies. He can do so by using the CLI: - - sr mpls policy te bsid xxxxx endpoint x.x.x.x color 12341234 - -Notice that an SR policy can have a single endpoint and a single color. Notice that the *endpoint* value is an IP46 address and the color a u32. - - -Then, for any BGP/Service route the user has to use the API to steer prefixes: - - sr steer l3 2001::/64 via next-hop 2001::1 color 1234 co 2 - sr steer l3 2001::/64 via next-hop 2001::1 color 1234 co 2 vpn-label 500 - -Notice that *co* refers to the CO-bits (values [0|1|2|3]). - -Notice also that a given prefix might be steered over several colors (same next-hop and same co-bit value). In order to add new colors just execute the API several times (or with the del parameter to delete the color). - -This variant is meant to be used in conjunction with a control plane agent that uses the underlying binary API bindings of *sr_mpls_steering_policy_add*/*sr_mpls_steering_policy_del* for any BGP service route received. \ No newline at end of file -- cgit 1.2.3-korg