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Where are we going?. 2 Some of the forces driving WLAN (re)design Migration to IPv6 Consumer devices in the enterprise Migration to the.

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Presentation on theme: "Where are we going?. 2 Some of the forces driving WLAN (re)design Migration to IPv6 Consumer devices in the enterprise Migration to the."— Presentation transcript:

1 Where are we going?

2 2 Some of the forces driving WLAN (re)design Migration to IPv6 Consumer devices in the enterprise Migration to the cloud

3 3 Why do we need VLANs? VLANs split up L2 subnets to control excessive broadcast & multicast traffic We sometimes use VLANs to segregate traffic for security VLANs can help us manage geographically distributed networks (addresses imply location) We sometimes use VLANs to segregate services and QoS Weve always done it this way VLAN pooling has been a widely-used (and useful) feature…

4 4 Why do we need VLANs? VLANs split up L2 subnets to control excessive broadcast & multicast traffic We sometimes use VLANs to segregate traffic for security VLANs can help us manage geographically distributed networks (addresses imply location) We sometimes use VLANs to segregate services and QoS Weve always done it this way VLAN pooling has been a widely-used (and useful) feature… But… VLAN pooling causes inefficient address usage And IPv6 (SLAAC) VLANs dont mix well with WLANs And managing multiple VLANs across a large network is challenging

5 5 Moving WLANs to IPv6 – SLAAC VLAN 1 1. RS to ff02::2 ICMPv6 type 133 (RS) 2. RA to ff02::1 ICMPv6 type 134 (RA) router lifetime 1800s preferred lifetime = 7d, valid lifetime = 30d RS RA RS RA RSRouter Solicitation RARouter Advertisement SLAACStateless Address Auto-Configuration DADDuplicate Address Detection ND, NS, NANeighbor Discovery, Solicitation, Advertisement MAC Address Network Identifier 64 bits Interface Identifier 64 bits 2001:0db8:1010:61ab:0219:71ff:fe64:3f00 IPv6 address discovery with SLAAC (State-Less Address Auto Configuration, RFC 4862) Routers send unsolicited Router Advertisements (RA) periodically (~ minutes) RA includes the network stub for the address, device adds a unique interface identifier to construct an address in a stateless protocol But more often, a device requests an address by sending a Router Solicitation (RS) to the well-known all routers address Controller assigns device to a pooled VLAN and forwards the RS to only the appropriate router On receipt of an RS, the router sends an RA to the all-nodes multicast address

6 6 Moving WLANs to IPv6 – RAs meet wireless VLAN 1 1. RS to ff02::2 ICMPv6 type 133 (RS) 2. RA to ff02::1 ICMPv6 type 134 (RA) router lifetime 1800s preferred lifetime = 7d, valid lifetime = 30d RA MAC Address list RAs multicasts are limited within their VLAN by switches…But has no concept of VLANs or multicast, only broadcast to all associated devices. So an RA for a device on one VLAN is received by devices on other VLANs. This affects BSSs serving devices from more than one VLAN, which comes about after mobility events or through VLAN pooling. IPv6 address discovery with SLAAC (State-Less Address Auto Configuration, RFC 4862) Controller assigns device to a pooled VLAN and forwards the RS to only the appropriate router On receipt of an RS, the router sends an RA to the all-nodes multicast address Controller forwards the multicast RS to all APs with a member of that multicast group RAs are broadcast over the air, all associated devices receive them

7 7 Consumer devices in the enterprise Several scenarios result in clients from multiple VLANs associating to the same AP This sows the seeds of the VLANs demise Mixed VLAN clients on one AP: i.Through VLAN pooling, by design ii.From mobility events, where devices move from one AP to another iii.Where VLANs are used to segregate, or manage traffic and clients are using different services

8 8 Moving WLANs to IPv6 – multiple VLANs VLAN 1 VLAN 2 2. RA to ff02::1 ICMPv6 type 134 (RA) router lifetime 1800s, preferred lifetime = 7d, valid lifetime = 30d RA MAC Address list With IPv6, devices construct multiple addresses, one per distinct RA received, by adding its MAC address to the RA global_routing_prefix + subnet_id. A device may choose to use any address from its list as its source address. IPv6 address discovery with SLAAC (State-Less Address Auto Configuration, RFC 4862) Controller assigns device to a pooled VLAN and forwards the RS to only the appropriate router On receipt of an RS, the router sends an RA to the all-nodes multicast address Controller forwards the multicast RS to all APs with a member of that multicast group RAs are broadcast over the air, all associated devices receive them and build multiple addresses

9 9 IPv6 address discovery with SLAAC (RFC 4862) Controller assigns device to a pooled VLAN and forwards the RS to only the appropriate router On receipt of an RS, the router sends an RA to the all-nodes multicast address RAs are broadcast over the air, all devices receive them Devices build multiple IPv6 addresses based on heard & overheard RAs When a device starts to transmit, only one of its IPv6 addresses matches the controllers VLAN mask. Packets with mismatched source addresses are dropped. Moving WLANs to IPv6 – confused addressing VLAN 1 VLAN 2 1. RS to ff02::2 ICMPv6 type 133 (RS) 2. RA to ff02::1 ICMPv6 type 134 (RA) router lifetime 1800s, preferred lifetime = 7d, valid lifetime = 30d RA MAC Address list The network learns VLAN assignments and check for incorrect source address as a security measure (e.g. anti-spoofing).

10 10 IPv6 SLAAC with VLAN pooling Where APs serve clients with mixed VLANs, some percentage of devices use the wrong address and traffic is dropped Solution: turn downstream multicast to unicast But devices still hear all RAs on the VLAN, regardless of where the RS came from. This can be a significant amount of extra traffic Moving to IPv6 – Solving mismatched IPv6 VLAN 1 VLAN 2 VLAN 3 VLAN 1 VLAN 2 RA MAC Address list

11 11 Multicast-to-unicast of IPv6 SLAAC RAs results in noticeably faster battery drain This appears to be a combination of the client radio staying in receive mode for longer periods (stays awake till it can contend for an uplink trigger frame)… And extra transmit operations to send frames required to retrieve buffered downlink and return to sleep mode Moving to IPv6 – Unicast vs Multicast beacon TIM multicast client radio in receive mode beacon TIM multicast client radio in receive mode unicast client transmits trigger data ack & sleep time Multicast downlink frames Multicast to unicast downlink frames

12 12 IPv6 SLAAC with VLAN pooling Where APs serve clients with mixed VLANs, some percentage of devices use the wrong address and traffic is dropped Solution: turn downstream multicast to unicast But now devices still hear all RAs on the VLAN, regardless of where the RS came from. This can be a significant amount of extra traffic … and this unicast traffic is a significant drain on battery life Moving to IPv6 – Solving mismatched IPv6 VLAN 1 VLAN 2 VLAN 3 VLAN 1 VLAN 2 RA MAC Address list What to do? Either… i.Prune RA traffic to only those devices that have outstanding RSs? ii.Make sure we dont mix VLANs on an AP? iii.Try making Wi-Fi VLAN-compliant? iv.Other ideas?

13 13 Some of the forces driving WLAN (re)design Consumer devices in the enterprise Migration to IPv6 Migration to the cloud

14 14 Consumer devices in the enterprise Consumer devices on a home network Reference model is a small L2 network i.Not many devices, plentiful bandwidth ii.Devices use multicast to discover each other, and services by Type and Name iii.… through mDNS / DNS-SN / Bonjour

15 15 mDNS and DNS-SD mDNS Query -serviceType (e.g.PTR) -domain mDNS Response -serviceName (e.g. GammaPrinter) mDNS Response -serviceName (e.g. BetaPrinter) mDNS Response -serviceName (e.g. AlphaPrinter) RFC 6762 Multicast DNS RFC 6763 DNS-based service discovery DNS Domain Name Service L2 network When a new service instance starts, it advertises the service to a multicast address with serviceType and serviceName. Listening devices add the service to their cached list. When an app requests a service by serviceType queries the OS-cached list for optional mDNS Query for the serviceType. When an app wants to use a service, mDNS Queries resolve the chosen serviceName to a hostName and IP address + port Some DNS-SD Service Types ippprinter appletvApple TV home-sharingiTunes Home Sharing ServiceType : Name App advertises service App requests service Announcements Queries Responses Announcements mDNS Advertisement -serviceType (e.g.PTR) -domain

16 16 mDNS & DNS-SD i.Every service instance publishes/advertises when it comes up and responds to queries on multicast. ii.Within a given service, all instances have visibility of all other instances… iii.… except across VLAN or L2 boundaries iv.Default is to flood packets mDNS & DNS-SD VLAN 1 VLAN 3 VLAN 2

17 17 mDNS & DNS-SD with network participation i.Network learns groupings by service and device ii.When a service instance transmits (on multicast mDNS), the network swallows the transmission iii.Network responds to mDNS DNS- SD Queries on behalf of service instances iv.When other devices in the group are in different VLANs, packets are forwarded across VLAN boundaries v.Default may be to block mDNS per-service mDNS-participating network architecture Rules to determine control forwarding (examples) Allow X service on the network Allow device/instance Y to see service instance X because - They are instances of the same service - They are on the same AP - They are in the same building - They owned by the same userid - Y has been authorized by the owner of X - They are instances of an uncontrolled service - X has been designated a shared instance (ethersphere) #show airgroup status AirGroup Service Information Service Status airplay Enabled airprint Enabled itunes Disabled allowall Disabled (ethersphere) #show airgroup blocked-queries AirGroup dropped Query IDs _touch-remote._tcp _sleep-proxy._udp 2 _vnc._tcp 1819 _mediatest._udp 91 _mediatest._tcp 22 Network intercepts mDNS service advertisements Transmits advertisements to selected devices on any VLAN Responds to service queries by sending selected responses VLAN 1 VLAN 2

18 Consumer devices in the enterprise mDNS & DNS-SD with network participation, network must be capable of: i.Identifying whether a service type is allowed ii.Identifying the group which should have visibility of each service instance

19 19 Subnets, VLANs and multicast control VLANs: network controls what a port can see Subnets: L2 domains require a router to connect, breaks multicast Multicast control: similar to VLANs but works across subnets

20 20 Proxy multicast architecture is not new Proxy ARP has been a feature of over-the-air WLANs for years, to limit traffic and provide security Concept extends to multicast control Also extends to IPv6 duplicate address discovery, neighbor discovery Who has A.B.C.D? A.B.C.D Over here, mate! ARP RFC 826 Multicast query Unicast response ARP proxy (802.11v, u e.g. ARP) Multicast filtering (802.11v FBMS e.g. VRRP) IPv6 Neighbor Discovery Proxy (e.g. NDP, ND, DAD)

21 21 Traffic forwarding layer Policy layer Identifies, synthesizes and forwards specific packets applies rules, e.g. this device or service instance is part of group X including these other members mDNS & DNS-SD with network participation i.Network takes the role of service directory away from the distributed mDNS model ii.Network can add and advertise its own services mDNS-participating network architecture mDNS Query -serviceType -domain mDNS Response -serviceName -(e.g. AlphaPrinter) mDNS Advertisement -serviceType -domain mDNS proxy External Configuration for groupings, permissions Internal policy decisions

22 22 Some of the forces driving WLAN (re)design Migration to the cloud Consumer devices in the enterprise Migration to IPv6

23 23 Monitoring and managing corporate activity from remote locations to cloud-resident applications i.Conventional model brings traffic to the data center from campus APs ii.And remote APs (VPN model over Internet) iii.As corporate locations become more distributed, and apps & services become cloud-resident, network managers become blind to corporate traffic iv.The only touch point for network managers will be an IT-supplied and managed AP Monitoring and control at the network edge Functions performed at the network edge: Radio configuration, monitoring and management… Authentication Firewall rules Traffic shaping and QoS Monitoring & reporting Access for troubleshooting

24 24 Some of the forces driving WLAN (re)design Migration to IPv6 Consumer devices in the enterprise Migration to the cloud New WLAN features in response to specific problems Multicast control (filtering & forwarding) is a powerful new technology An opportunity to re-think network design

25 25 Increase the size, reduce the number of VLANs to solve IPv6 issues Why do we need VLANs? Solved by network multicast control Solved (as well as it was by VLANs) Mobility-aware network does this better Single-VLAN networks can be an IPv6 overlay over existing IPv4 designs… Or an opportunity to simplify the whole network VLAN 1 VLAN 2 VLAN 3 IPv4 IPv6 VLANs split up L2 subnets to control excessive broadcast & multicast traffic We sometimes use VLANs for security VLANs can help us manage geographically distributed networks (addresses imply location) We sometimes use VLANs to segregate services and QoS

26 26 Software Defined Networking (SDN) SDN Benefits Centralized management and control of networking devices from multiple vendors Increased network reliability, security, uniform policy enforcement, and fewer configuration errors Granular network control with the ability to apply comprehensive and wide-ranging policies at the session, user, device, and application levels Better end-user experience as applications exploit centralized network state information to seamlessly adapt network behavior to user needs. Software-defined networking decouples network control (routing and switching traffic) from the physical network topology Network intelligence and state are centralized, network topology is abstracted and virtualized The Open Networking Foundation consortium is leading standardization efforts https://www.opennetworking.org/ OpenFlow is a protocol that facilitates communication between SDN Controllers and SDN capable network elements. * https://www.opennetworking.org/images/stories/downloads/white-papers/wp-sdn-newnorm.pdf

27 27 Traffic forwarding layer Policy layer identifies, synthesizes and forwards specific packets applies rules, e.g. this device or service instance is part of group X including these other members Abstract the network model to a policy layer Policy layer interfaces to external APIs, OpenFlow External APIs export sensing information, accept reconfiguration Abstracting the network model Move to another AP Internal policy decisions Voice / Video Server Connection setup alert Security / Remediation Server New device alert Required action (response) New ACL / firewall Adjust QoS per stream Cant do this one, try again

28 28 Sensing at the network edge Only at the edge can the network sense Device radio characteristics Device authentication status Unassociated devices All intrusion attempts Radio information -Signal level -SNR radio mgmt management -Associated -Data rate -Frame error rate -MAC -Sleeping Authenticati on -Status -Identity -Role -Blacklist L2 -ARP -VLAN -mDNS IP -DHCP -IP address Multicast -IGMP -MC Neighbors L4-7 -Sessions & protocols -Destinations, ports -Rates -QoS Mobility awareness -Origin & location -Roaming history -AP load -Neighbor APs L2 traffic & services L3 traffic & services connected device

29 29 Control at the network edge Only at the edge can the network control all aspects of association, authentication, discovery and connectivity e.g. blacklist association based on traffic protocol e.g. move APs based on a new session Radio information -Signal level -SNR management -Associated -Data rate -Frame error rate -MAC -Sleeping L2 -ARP -VLAN -mDNS IP -DHCP -IP address Multicast -IGMP -MC Neighbors L4-7 -Sessions & protocols -Destinations, ports -Rates -QoS Mobility awareness -Origin & location -Roaming history -AP load -Neighbor APs connected (or unconnected) device Blacklist association Apply or change QoS Devices & services discovery Determine Reachability Synthesize responses Move to best AP

30 30 A better way to think about architecture Sensing layer Policy enforcement layer Local policy decision layer SDN policy decision layer report radio state, state, authentication, multicast services, traffic apply authentication rules, firewall rules, QoS policy, multicast service manipulation Abstract the wireless network model and make decisions for authentication, service whitelisting, load balancing… reconfigure network to allow for changes and coordinate outside the wireless edge

31 31 Some of the forces driving WLAN (re)design Migration to IPv6 The network hollows out The edge is used for sensing and reporting Policy definitions allow the network to dynamically reconfigure in response to traffic & external events SDN APIs allow the network to dynamically reconfigure in response to external requirements Consumer devices in the enterprise Migration to the cloud

32 Where we are going


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