Internet DRAFT - draft-zartbot-srou-control
draft-zartbot-srou-control
SPRING K. Fang
Internet-Draft Cisco Systems, Inc.
Intended status: Experimental Y. Li
Expires: 20 February 2021 Google, Inc.
F. Cai
X. Jiang
Cisco Systems, Inc.
19 August 2020
Distributed KV Store based Routing protocol for SR over UDP(SRoU)
draft-zartbot-srou-control-00
Abstract
This document defines the Distributed KV store based routing protocol
for Segment Routing over UDP.
Status of This Memo
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This Internet-Draft will expire on 20 February 2021.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Specification of Requirements . . . . . . . . . . . . . . 2
1.2. Motivation . . . . . . . . . . . . . . . . . . . . . . . 2
1.3. Overview . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Node abstraction and registration . . . . . . . . . . . . . . 3
2.1. Node Label allocation . . . . . . . . . . . . . . . . . . 4
2.2. Node registration . . . . . . . . . . . . . . . . . . . . 4
3. SRoU Locator and Route . . . . . . . . . . . . . . . . . . . 4
4. Node Keepalive . . . . . . . . . . . . . . . . . . . . . . . 4
5. Link State . . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Sercurity Key . . . . . . . . . . . . . . . . . . . . . . . . 5
7. Overlay Routing . . . . . . . . . . . . . . . . . . . . . . . 5
8. Control Policy . . . . . . . . . . . . . . . . . . . . . . . 6
8.1. Route control . . . . . . . . . . . . . . . . . . . . . . 6
8.2. Access Control . . . . . . . . . . . . . . . . . . . . . 6
8.3. User identity . . . . . . . . . . . . . . . . . . . . . . 6
9. Distributed KV Store . . . . . . . . . . . . . . . . . . . . 6
10. Security Considerations . . . . . . . . . . . . . . . . . . . 7
11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 7
Informative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
This draft provides a contol plane support for SRoU(Segment Routing
over UDP).
Discussion of this work is encouraged to happen on GitHub repository
which contains the draft: https://github.com/zartbot/draft-quic-sr
(https://github.com/zartbot/draft-quic-sr)
1.1. Specification of Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
1.2. Motivation
SRoU support udp transport session over internet, but it lack of
reachability detection and routing control, existing routing protocol
like BGP-EVPN did not provide Dynamic NAT traversal capability.
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This document provide a distributed KV store based routing protocol
for SRoU.
1.3. Overview
The routing protocol is based on source routing, each of the ingress
node cloud get the overlay prefix and dest location mapping from
distributed KV store, then the ingress node could fetch linkstate
database from this KV store and execute A* algorithm to search the
candidate path which meet the SLA requirement.
2. Node abstraction and registration
Each Node has the following attribute
1. Role: the system contains different node type, role attribute is
a uint16 value which contains:
+------+----------+---------------------------------------------+
| Type | Name | Section |
+======+==========+=============================================+
| 0x0 | STUN | This node is used as a STUN server to help |
| | | other nodes discovery their public |
| | | address.This node must deploy with a public |
| | | internet address or behind static 1:1 NAT |
+------+----------+---------------------------------------------+
| 0x1 | Fabric | This node type is used as a interim node to |
| | | relay the SRoU traffic, this node MUST |
| | | initial TWAMP link probe to other Fabric |
| | | node and report linkstate to KV Store. |
+------+----------+---------------------------------------------+
| 0x2 | Linecard | This node type is used to connect existing |
| | | network, it could use TWAMP probe other |
| | | Fabric Node or Linecard node |
+------+----------+---------------------------------------------+
Table 1: Node Role
1. SiteID: uint32 number, defined the node which belongs to same
site or Automomous System.
2. SystemName: unique string type to indicate a node.
3. Label: unique 24bit value, allocation algorithm is described in
the following section.
4. Location: Optional filed. It contains two float32 value(latitude
and longitude) to indicate the Geo location.
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2.1. Node Label allocation
Each node initial TLS session to Distributed KV Store, and fetch a
distributed lock with key "/lock/systemlabel". The node will fetch
prefix "/systemlabel" to get all label mapping once it get the lock.
Then it will assign the smallest unpresent int "X" in the list as
it's system label, and register it to KV store by key="/systemlabel/
X", then it could release the distributed lock. All of the fabric
node MUST listen the "/systemlabel" to update it's local node mapping
table, Linecard node may fetch the "/systemlabel" key when it need to
optimize the local route.
This System Label could be used for cSID encoding or VPN based client
linecard node convert to it's tunnel address.
2.2. Node registration
Each node will send Key="/node/role/systemName" and Value="
SiteID,SystemLabel, Lat,Long" to the distributed KV store.
3. SRoU Locator and Route
Each node may have multiple underlay socket which may behind the
dynamic NAT, it MUST fetch the STUN list from "/node/stun" and
"/service/stun" to get the STUN server address list, then send the
SRoU OAM-STUN packet to the random selected stun server to get the
public address.
Once the socket get the public address, it will encode the udp socket
info as a SRoU Locator:
"SystemName/Color/LocalIP:Port/PublicIP:Port/LocalInterface/TXBW/
RXBW"
If the local socket has public address and port information, it could
be added in the service list.
The node MUST update it local servicelist to distributed KV store by:
Key= "/service/role/systemName" Value= "SRoULocator1,SRoULocator2"
4. Node Keepalive
Each KV pair registration MUST have a leasetime and keepalive timer,
Once the Node out of service and disconnected, the KV store MUST
withdraw the KV pair after lease timeout.
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5. Link State
Each Fabric Node must watch the "/service/fabric" key prefix to
update its local SRoU Service list database. It MUST initial TWAMP
session over the service udp socket to measure the link performance
and reachablity.
Linkstate measurement result COULD send to the KV store to construct
the linkstate Database by the following Key Value type:
Key="/stats/linkstate/SRC_SRoU_Locator->DST_SRoU_Locator" value=
TWAMP measured jitter/delay/loss result and underlay interface load.
The Node CPU,Memory usage also could be updated by: Key="/stats/node/
SystemName" Value="CPULoad,MemoryUsage"
An telemetry analytics node could watch key prefix ="/stats" for
assurance and AIOps based routing optimization.
6. Sercurity Key
Each node may update it node key or per socket key , or per session
pair key to the KV Store:
Key="/key/SystemName" Value="Key1,Key2"
Key="/key/socket/SRoU_Locator" Value="Key1,Key2"
Key="/key/session/SRC_SRoU_Locator->DST_SRoU_Locator"
Value="Key1,Key2"
During Rekey, the node must update both OldKey and newKey to the KV
Store and accept both Key in a while to wait the entire system sync
to the new key.
7. Overlay Routing
RouteDistinguish could encode by SystemName + local VNID The overlay
routing prefix is encoded as below:
Type-2 EVPN Route Key="/route/2/exportRT/RD/MAC/IP"
Value="VNID/SystemName/PolicyTag"
Type-5 EVPN Route
Key="/route/5/exportRT/RD/IPPrefix/IPMask" Value="VNID/SystemName/
PolicyTag"
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Each of the linecard node could based on import RT list to watch key
prefix ="/route/2/importRT" and "/route/5/importRT" to sync the
routing table.
Each linecard node could selective fetch the "/stats/linkstate" to
get the toplogy information and execute flexibile algorithm(SPF,A*
search) to calculate the candidate path, then enforce it to its
forwarding table.
8. Control Policy
8.1. Route control
Inspired by BGP FlowSpec,Network operator could update the control
policy to the entire system by using:
Key="/control/RT/2/SRC_MAC/SRC_IP/DST_MAC/DST_IP"
Key="/control/RT/5/SRC_Prefix/SRC_Mask/DST_Prefix/DST_Mask"
Value="Action" /"SR Locator list"
8.2. Access Control
Each node may use the SRoU flowID field as a token based access
control. This token could grant or revoke by a policy engine.
Key="/token/permit/flowid" Key="/token/block/flowid"
Each node could sync this table to execute the access control policy.
8.3. User identity
Each of the endpoint may have it's identity or group policy tags, it
could be updated by
key="/identity/userid/user_device_id" value="group policy tags"
Group policy could be updated and store in ETCD by
key="/policy/src_grp/dst_grp" value="actions"
9. Distributed KV Store
ETCD is used in our prototype, we deploy an etcd cluster in main
datacenter and place many of the proxy node on public cloud to make
sure the node could be available connect to the entire system. In
some on-prem deployment, each of the nodes could act as a ETCD proxy
to help other node register to KV store.
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10. Security Considerations
All of the control connection is TLS based and MUST validate the
server and client certification.
11. IANA Considerations
Acknowledgements
The following people provided substantial contributions to this
document:
* Yijen Wang, Cisco Systems, Inc.
Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
Authors' Addresses
Kevin Fang
Cisco Systems, Inc.
Email: zartbot.ietf@gmail.com
Yinghao Li
Google, Inc.
Email: liyinghao@gmail.com
Feng Cai
Cisco Systems, Inc.
Email: fecai@cisco.com
Xing Jiang
Cisco Systems, Inc.
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Email: jamjiang@cisco.com
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