Download Animation - Cisco Communities

Architecture & Solutions Group
US Public Sector Advanced Services
Mark Stinnette, CCIE Data Center #39151
Date 28 August 2013
Version 1.2.2
© 2013 Cisco and/or its affiliates. All rights reserved.
1
This Quick Start Guide (QSG) is a Cookbook style guide to Deploying Data Center
technologies with end-to-end configurations for several commonly deployed architectures.
This presentation will provide end-to-end configurations mapped directly to commonly
deployed data center architecture topologies. In this cookbook style; quick start guide;
configurations are broken down in an animated step by step process to a complete end-toend good clean configuration based on Cisco best practices and strong recommendations.
Each QSG will contain set the stage content, technology component definitions,
recommended best practices, and more importantly different scenario data center
topologies mapped directly to complete end-to-end configurations. This QSG is geared for
network engineers, network operators, and data center architects to allow them to quickly
and effectively deploy these technologies in their data center infrastructure based on
proven commonly deployed designs.
© 2013 Cisco and/or its affiliates. All rights reserved.
2
Benefits Overview
Geographically dispersed data centers provide added application resiliency and workload allocation flexibility. To this end, the
network must provide Layer 2, Layer 3 and storage connectivity between data centers. Connectivity must be provided without
compromising the autonomy of data centers or the stability of the overall network. OTV provides an operationally optimized
solution for the extension of Layer 2 connectivity across any transport. OTV is therefore critical to the effective deployment of
distributed data centers to support application availability and flexible workload mobility.
OTV is a "MAC address in IP" technique for supporting Layer 2 VPNs to extend LANs over any transport. The transport can
be Layer 2 based, Layer 3 based, IP switched, label switched, or anything else as long as it can carry IP packets. By using
the principles of MAC routing, OTV provides an overlay that enables Layer 2 connectivity between separate Layer 2 domains
while keeping these domains independent and preserving the fault-isolation, resiliency, and load-balancing benefits of an IPbased interconnection.
Overlay Transport Virtualization (OTV) provides the following benefits:
• Scalability
Extends Layer 2 LANs over any network that supports IP (Transport agnostic)
Designed to scale across multiple data centers
• Simplicity
Supports transparent deployment over existing network without redesign
Requires minimal configuration commands
• Resiliency
Preserves existing Layer 3 failure boundaries
Includes built-in loop prevention
Failure boundary preservation and site independence preservation (failover isolation between data centers)
• Efficiency
Optimized available bandwidth, by using equal-cost multi-pathing and optimal multicast replication
Multipoint connectivity
Fast failover
• Virtual Machine Mobility
© 2013 Cisco and/or its affiliates. All rights reserved.
3
Benefits Overview
Additional benefits of using OTV for Layer 2 extension:
• No need for Ethernet over Multiprotocol Label Switching (EoMPLS) or Virtual Private LAN Services (VPLS)
deployment for Layer 2 extensions
• Use any network transport that supports IP
• Provision of Layer 2 and Layer 3 connectivity using the same dark fiber connections
• Native Spanning Tree Protocol (STP) isolation:
No need to explicitly configure Bridge Data Protocol Unit (BPDU) filtering
• Native unknown unicast flooding isolation:
Unknown unicast not sent to the overlay
• Address Resolution Protocol (ARP) optimization with the OTV ARP cache
• Simplified provisioning of First Hop Redundancy Protocol (FHRP) isolation
• Simplified addition of sites
© 2013 Cisco and/or its affiliates. All rights reserved.
4
L3 & Join Interfaces
L2 Internal Interfaces
Commonly Deployed Designs :: Aggregation Layer
 Most Commonly Deployed
 No Network Redesign or Re-Cabling
 Join Interface connects back through the VDC
that has the SVIs on them
 Separate OTV VDC or Appliance Switch
OTV On a Stick
Inline OTV
 Dedicated Uplink for DCI
 Join Interface has a dedicated link out to the
DCI transport (Core or WAN Edge)
 Separate OTV VDC or Appliance Switch
© 2013 Cisco and/or its affiliates. All rights reserved.
5
Terminology & Components
OTV delivers Layer 2 extensions over
any type of transport infrastructure
vPC Domain
(vPC or vPC+ Supported)
Join Interfaces
Point-to-Point Layer 3 interface
M-Series Line Cards Only
Multicast or Unicast
Transports Supported
Authoritative Edge Device (AED )
Odd VLANs
M-Series Line Cards Supported
F1 & F2E Line Cards Supported in 6.2(2)
© 2013 Cisco and/or its affiliates. All rights reserved.
SVI Separation on the Aggregation VDC
Peer-Link
OTV Edge Device
Performs OTV Functions
OTV Overlay Interface
Authoritative Edge Device (AED )
Even VLANs
Internal Interfaces
Regular Layer 2 & Carries VLANs extended over OTV
6
Terminology & Components
OTV encapsulates packets into an IP header and where it sets the Don't
Fragment (DF) bit for all OTV control and data packets crossing the transport
network. The encapsulation adds 42 bytes to the original IP maximum transition
unit (MTU) size. So it is a best practice to configure the join interface and all
Layer 3 interfaces that face the IP core between the OTV edge devices with
the max possible MTU size supported by the transport
WEST DC
HSRP Active
EAST DC
HSRP Standby
HSRP Active
HSRP Standby
Site ID 1
Site ID 2
Site VLAN 99
Site VLAN 99
Filter HSRP
Filter HSRP
Filter HSRP
Filter HSRP
Site ID & Site VLAN are Deployed on Both OTV Edge Devices
Site Identifier ::
Use same Site ID within a single data center
Use unique Site ID between different data centers
Site VLAN ::
Use same Site VLAN between different data centers (not mandatory)
Site VLAN is active on internal interfaces but don’t extend Site VLAN
The Site VLAN should be a dedicated VLAN
© 2013 Cisco and/or its affiliates. All rights reserved.
Filtering FHRP in both data centers on the OTV VDC is
required to allow for existence of the same default
gateway in different locations thus optimizing the
outbound traffic flows (server to client direction)
7
Terminology & Components :: Layer 2 & Layer 3 Features
Layer 3 Interface (Towards Routed Core)
interface ethernet x/y
mtu 9216
ip address x.x.x.x/30
ip router ospf 1 area 0
ip ospf network point-to-point
ip pim sparse-mode
Layer 3 Interface (Towards OTV Join)
interface ethernet x/z
mtu 9216
ip address x.x.x.x/30
ip router ospf 1 area 0
ip ospf network point-to-point
ip pim sparse-mode
ip igmp version 3
Must enable Site
VLAN [x] on trunk
towards the
Aggregation Switch
[make vlan active]
OTV Join Interfaces
OTV Internal Interfaces
Aggregation Internal Interfaces
interface port-channel x
switchport
switchport mode trunk
switchport trunk allowed vlan x, y
interface port-channel x
switchport
switchport mode trunk
switchport trunk allowed vlan y
vpc x
interface ethernet x/y - z
channel-group x force mode active
© 2013 Cisco and/or its affiliates. All rights reserved.
interface ethernet x/y
channel-group x force mode active
interface ethernet x/y
mtu 9216
ip address x.x.x.x/30
ip router ospf 1 area 0
ip ospf network point-to-point
ip igmp version 3
Aggregation Switch :: Enable PIM
feature pim
ip pim rp-address x.x.x.x group-list 224.0.0.0/4
ip pim ssm range 232.0.0.0/8
8
Additional Features, Terminology, & Components
Feature
Overview
Edge Device
The OTV Edge Devices performs OTV functions, multiple OTV Edge Devices can exist at each site. OTV
requires the Transport Services (TRS) license. If you create the OTV Edge Device in a non default VDC; it
requires the Advanced Services license.
Internal Interfaces
Internal interfaces are the site facing interfaces of the Edge device; carrying VLANs extended through OTV.
They are regular Layer 2 interfaces, switch ort mode trunk, and typically port channels in a vPC. No OTV
configuration is required on these interfaces.
Join Interfaces
Join interfaces are one of the uplink of the Edge device; they are Layer 3 point-to-point routed interfaces
(physical interface, port channel, or sub-interface). Its used to physically ‘join’ the Overlay network. No OTV
specific configuration required.
Overlay Interface
Virtual interface is where most of the OTV configuration happens, logical multi-access multicast-capable
interface, encapsulates Layer 2 frames in IP unicast or multicast.
Authoritative Edge
Device (AED)
The AED is responsible for MAC address advertisement for its VLANs; forwarding its VLANs traffic inside
and outside the site. The extended VLANs are split across the AEDs (even & odd) in OTV multi-homing.
Site VLAN
The OTV Site VLAN is used to discover OTV neighbor edge devices in same local site.
Site Identifier
Same site Edge devices must use a common unique Site ID. Site ID is included in the control plane; an
overlay will not come up until a Site ID is configured; and should be on all local OTV Edge devices.
MTU
Join interfaces and neighboring Core interfaces need to have MTU of ≥ 1542 (hard requirement). Best
practice to the max possible MTU size supported by the transport
FHRP Isolation
Filtering FHRP messages across the OTV Overlay allows to provide the same active default gateway in each
data center site. Note, in future releases OTV will offer a simple command to enable these filtering
capabilities.
SVI Separation
OTV currently enforces SVI separation for the VLANs being extended across the OTV link, meaning OTV is
usually in its own VDC for OTV functions and have SVIs in another Aggregation VDC.
© 2013 Cisco and/or its affiliates. All rights reserved.
9
Additional Features, Terminology, & Components
Feature
Overview
OTV Requirements
Nexus 7000 Series or ASR routers. LAN ADVANCED SERVICES (VDC) license & TRANSPORT
SERVICES (OTV/LISP) license. An M-Series line card is required in the OTV VDC for OTV functions.
Multicast Transport
Multicast transport (OTV Control Plane) is ideal for connecting a higher number of sites. OTV Neighbor
relationships are built over a multicast enabled core / transport infrastructure. All OTV edge devices can
be configured to join a specific ASM (Any Source Multicast) group where they simultaneously play the
role of receiver and source. Edge devices join a multicast group; adjacencies are maintained over that
multicast group and a single update reaches all neighbors.
Unicast Transport
Supported since NX-OS release 5.2. Unicast-only transport (OTV Control Plane) is ideal for connecting a
small number of sites. Requires the adjacency server. Each OTV devices would need to create multiple
copies of each control plane packet and unicast them to each remote OTV device part of the same logical
overlay.
Adjacency Server
Used in OTV Unicast mode; usually enabled on an OTV Edge device; can have a primary and secondary;
and all other OTV Edge client devices are configured with the address of the adjacency server. The goal
is to be able to communicate with all the remote OTV devices, each OTV node needs to know a list of
neighbors to replicate the control packets to. Rather than statically configuring in each OTV node the list
of all neighbors, a simple dynamic means is used to provide this information; this adjacency server.
OTV Extend VLAN
Enables OTV advertisements for those VLANs. OTV will not forward Layer 2 packets for VLANs not in
the extended VLAN range for the overlay interface. Assign a VLAN to only one overlay interface.
OTV Authentication
OTV supports authentication of Hello messages along with authentication of PDUs.
Dual Homed OTV Edge
Devices
Leverage vPC or vPC+ for dual homed OTV Edge devices. The concept of the AED role along with the
site vlan allows multi-homing OTV Edge devices.
© 2013 Cisco and/or its affiliates. All rights reserved.
10
Additional Features, Terminology, & Components
Feature
Overview
Selective Unicast
Flooding
In 6.2(2); some applications rely on unknown unicast frames; so selective unicast flooding can be enabled
on a per mac address per vlan to accommodate silent or uni-directional hosts. OTV default behavior is
no unknown unicast forwarding.
Command used: otv flood mac [xxxx.yyyy.zzzz] vlan [#]
Dedicated Data
Broadcast Forwarding
In 6.2(2); Dedicated broadcast group is a configurable option; useful for QoS purposes. A dedicated
multicast group can be configured for all broadcast transmission in an OTV overlay that utilizes multicast
transmission on the underlying OTV network. By default, the broadcast and control traffic will share the
same multicast group address. The broadcast group needs to be configured on all OTV Edge devices
connected to the OTV overlay network.
Source Interface with
Loopback
In 6.2(2); Logical interfaces as Join Interfaces; Loopback to guarantee interfaces is up/up. An OTV Edge
device can be configured to use a loopback interface as the join-interface for an OTV overlay to increase
availability. This feature requires the OTV Edge device to participate in the core PIM multicast domain to
support multiple paths. Prior to this feature only single homed Ethernet and port channel interface
options were available.
OTV VLAN Translation
In 6.2(2); VLAN translation allows OTV to map a local VLAN (in DC 1) to a remote VLAN (in DC 2). In
previous NX-OS releases, the extended VLANs had to be identical in each site (ie. X to X). With the
VLAN mapping feature, VLANs can be translated, so they can be different in each site (ie. X to Y to Z)
providing more flexible deployment options. Both multicast and unicast enabled IP core networks are
supported. VLAN mappings have a one-to-one relationship.
© 2013 Cisco and/or its affiliates. All rights reserved.
11
Supported Line Card Topologies :: NX-OS 6.1 and Prior Releases
Aggregation VDC
• OTV VDC must use only M-Series ports for both Internal and Join Interfaces
[M1-48, M1-32, M1-08, M2-Series]
• OTV VDC Types (M-only)
• Aggregation VDC Types (M-only, M1-F1 or F2/F2E)
© 2013 Cisco and/or its affiliates. All rights reserved.
12
Supported Line Card Topologies :: NX-OS 6.2 and Later Releases
Aggregation VDC
• OTV VDC Join Interfaces must use only M-Series ports
[M1-48, M1-32, M1-08, M2-Series]
• OTV VDC Internal Interfaces can use M-Series, F1 and F2E ports (F1 and F2E must be in Layer 2 proxy mode)
• OTV VDC Types (M-only, M1-F1, M1-F2E)
• Aggregation VDC Types (M-only, M1-F1, M1-F2E, F2, F2E, F2F2E)
© 2013 Cisco and/or its affiliates. All rights reserved.
13
OTV Characteristics
 2-wide 7k Aggregation VDC
 Multi-homed OTV VDC
 Multicast enabled transport
 Extend VLAN 10
Quick Start Guide Assumptions
Physical View – Connectivity Map
Layer 3 routed point-to-point interfaces. Will be using OSPF as the routing protocol.
Layer 2 interfaces. The Aggregation VDC connects through vPC to the OTV VDC.
© 2013 Cisco and/or its affiliates. All rights reserved.
14
Perform Configuration Steps at
Both DC Sites (East & West)
Create Aggregation & OTV VDCs
[Admin / Default VDC]
[Admin / Default VDC]
no vdc combined-hostname
no vdc combined-hostname
vdc AGG-1
vdc AGG-1 limit-resource module-type m1 f1 m1xl m2xl
cpu-share 5
allocate interface Ethernet [….]
vdc AGG-2
vdc AGG-2 limit-resource module-type m1 f1 m1xl m2xl
cpu-share 5
allocate interface Ethernet [….]
vdc OTV-1
vdc OTV-1 limit-resource module-type m1 m1xl m2xl
cpu-share 5
allocate interface Ethernet [….]
vdc OTV-2
vdc OTV-2 limit-resource module-type m1 m1xl m2xl
cpu-share 5
allocate interface Ethernet [….]
Verify the Nexus 7000 has the proper licenses to support OTV and VDC.
Step 1 :: install | validate licenses
Step 2 :: create aggregation VDC
Step 3 :: create OTV VDC
OTV requires the Transport Services license
VDC requires the Advanced Services license
install license bootflash:///lan_advanced_services_pkg.lic
install license bootflash:///lan_transport_services_pkg.lic
show license usage
Allocate the Interfaces to appropriate VDC role accordingly
© 2013 Cisco and/or its affiliates. All rights reserved.
15
Perform Configuration Steps at
Both DC Sites (East & West)
Configure Aggregation VDC :: Layer 2 vPC (Option)
feature lacp
feature vpc
feature lacp
feature vpc
vlan 10-20
vlan 10-20
spanning-tree pathcost method long
spanning-tree port type edge bpduguard default
spanning-tree port type edge bpdufilter default
no spanning-tree loopguard default
spanning-tree pathcost method long
spanning-tree port type edge bpduguard default
spanning-tree port type edge bpdufilter default
no spanning-tree loopguard default
spanning-tree vlan 10-20 priority 0
spanning-tree pseudo-information
vlan 10-20 root priority 4096
vlan 1-10 designated priority 8192
vlan 11-20 designated priority 16384
spanning-tree vlan 10-20 priority 0
spanning-tree pseudo-information
vlan 10-20 root priority 4096
vlan 1-10 designated priority 16384
vlan 11-20 designated priority 8192
vpc domain 1
role priority 1
system-priority 4096
peer-keepalive destination [….] source [….] vrf
management
peer-switch
peer-gateway
auto-recovery
auto-recovery reload-delay
delay restore 30
ip arp synchronize
vpc domain 1
role priority 2
system-priority 4096
peer-keepalive destination [….] source [….] vrf
management
peer-switch
peer-gateway
auto-recovery
auto-recovery reload-delay
delay restore 30
ip arp synchronize
interface port-channel 2
switchport
switchport mode trunk
switchport trunk allowed vlan 10-20
spanning-tree port type network
vpc peer-link
interface port-channel 2
switchport
switchport mode trunk
switchport trunk allowed vlan 10-20
spanning-tree port type network
vpc peer-link
interface e3/1 , e4/1
channel-group 2 force mode active
© 2013 Cisco and/or its affiliates. All rights reserved.
See QSG :: vPC for more details …
interface e3/1 , e4/1
channel-group 2 force mode active
16
Perform Configuration Steps at
Both DC Sites (East & West)
Configure Aggregation VDC :: Layer 2 FabricPath vPC+ (Option)
feature lacp
feature vpc
install feature-set fabricpath
feature-set fabricpath
feature lacp
feature vpc
install feature-set fabricpath
feature-set fabricpath
Default / Admin
VDC Only
Default / Admin
VDC Only
vlan 10-20
mode fabricpath
vlan 10-20
mode fabricpath
fabricpath switch-id 10
fabricpath switch-id 11
fabricpath domain default
root-priority 255
fabricpath domain default
root-priority 254
spanning-tree pseudo-information
vlan 10-20 root priority 0
spanning-tree pseudo-information
vlan 10-20 root priority 0
vpc domain 1
role priority 1
system-priority 4096
peer-keepalive destination [….] source [….] vrf
management
peer-gateway
auto-recovery
auto-recovery reload-delay
delay restore 30
ip arp synchronize
fabricpath switch-id 1000
vpc domain 1
role priority 2
system-priority 4096
peer-keepalive destination [….] source [….] vrf
management
peer-gateway
auto-recovery
auto-recovery reload-delay
delay restore 30
ip arp synchronize
fabricpath switch-id 1000
interface port-channel 2
switchport mode fabricpath
vpc peer-link
interface port-channel 2
switchport mode fabricpath
vpc peer-link
interface e3/1 , e4/1
channel-group 2 force mode active
© 2013 Cisco and/or its affiliates. All rights reserved.
See QSG :: FabricPath for more details …
interface e3/1 , e4/1
channel-group 2 force mode active
17
Perform Configuration Steps at
Both DC Sites (East & West)
Configure Aggregation VDC :: Layer 3 Infrastructure
feature ospf
feature interface-vlan
feature hsrp
feature ospf
feature interface-vlan
feature hsrp
vlan 10 – 20
vlan 10 – 20
interface loopback0
ip address [….]/32
interface loopback0
ip address [….]/32
router ospf 1
router-id [….]
log-adjacency-changes detail
auto-cost reference-bandwidth 100Gbps
router ospf 1
router-id [….]
log-adjacency-changes detail
auto-cost reference-bandwidth 100Gbps
interface e1/1
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/1
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/10
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/10
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface vlan 10
ip address 10.10.10.2/24
no ip redirects
ip router ospf 1 area 0.0.0.0
ip ospf passive-interface
hsrp 1
preempt
priority 110
ip 10.10.10.1
interface vlan 10
ip address 10.10.10.3/24
no ip redirects
ip router ospf 1 area 0.0.0.0
ip ospf passive-interface
hsrp 1
preempt
ip 10.10.10.1
© 2013 Cisco and/or its affiliates. All rights reserved.
Allocate the following accordingly ::
 IP addressing
 OSPF areas
 SVIs & HSRP Groups
18
Perform Configuration Steps at
Both DC Sites (East & West)
Configure OTV :: Layer 2 & Layer 3 Infrastructure @ Aggregation
feature ospf
feature lacp
feature vpc
feature ospf
feature lacp
feature vpc
interface e 1/2
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e 1/2
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10
vpc 10
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10
vpc 10
interface port-channel 20
switchport
switchport mode trunk
switchport trunk allowed vlan 10
vpc 20
interface port-channel 20
switchport
switchport mode trunk
switchport trunk allowed vlan 10
vpc 20
interface e5/1
channel-group 10 force mode active
interface e5/1
channel-group 10 force mode active
interface e6/1
channel-group 20 force mode active
interface e6/1
channel-group 20 force mode active
Step 1 :: configure L3 link towards OTV Join Interface
Step 2 :: configure L2 vPC towards OTV Internal Interface
© 2013 Cisco and/or its affiliates. All rights reserved.
19
Perform Configuration Steps at
Both DC Sites (East & West)
Configure OTV :: Layer 2 & Layer 3 Infrastructure @ OTV VDC
feature ospf
feature lacp
feature ospf
feature lacp
vlan 10
vlan 10
spanning-tree vlan 10 priority 32768
spanning-tree vlan 10 priority 32768
interface loopback0
ip address [….]/32
interface loopback0
ip address [….]/32
router ospf 1
router-id [….]
log-adjacency-changes detail
auto-cost reference-bandwidth 100Gbps
router ospf 1
router-id [….]
log-adjacency-changes detail
auto-cost reference-bandwidth 100Gbps
interface e 1/9
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e 1/9
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10
interface e2/1, e2/2
channel-group 10 force mode active
© 2013 Cisco and/or its affiliates. All rights reserved.
Step 1 :: configure OTV Join Interfaces
Step 2 :: configure OTV Internal Interfaces
Step 3 :: create vlan to extend
interface e2/1, e2/2
channel-group 10 force mode active
20
Perform Configuration Steps at
Both DC Sites (East & West)
Configure OTV :: Enable Jumbo MTU
feature ospf
feature lacp
feature vpc
feature ospf
feature lacp
feature vpc
vlan 10 – 20
vlan 10 – 20
interface e 1/2
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e 1/2
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/10
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/10
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/1
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e1/1
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
feature ospf
feature lacp
feature vpc
feature ospf
feature lacp
feature vpc
vlan 10
vlan 10
interface e 1/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e 1/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
© 2013 Cisco and/or its affiliates. All rights reserved.
Step 1 :: increase MTU on Join Interfaces
Step 2 :: increase MTU on all Layer 3 Interfaces
21
Perform Configuration Steps at
Both DC Sites (East & West)
Configure OTV :: Enable Required Multicast
feature ospf
feature lacp
feature vpc
feature pim
ip pim rp-address [x.x.x.x] group-list 224.0.0.0/4
ip pim ssm range 232.0.0.0/8
Step 1 :: enable PIM
Step 2 :: configure PIM sparse mode [AGG VDC]
(on all intra & inter data center Layer 3 links)
Step 3 :: configure IGMP v3 [AGG & OTV VDC]
(join interfaces only)
Step 4 :: configure Rendezvous Point (RP)
Step 5 :: configure Source-Specific Multicast (SSM)
feature ospf
feature lacp
feature vpc
feature pim
ip pim rp-address [x.x.x.x] group-list 224.0.0.0/4
ip pim ssm range 232.0.0.0/8
interface e1/1
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
interface e1/1
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
interface e 1/2
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
ip igmp version 3
interface e 1/2
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
ip igmp version 3
interface e1/10
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
interface e1/10
mtu 9216
ip address [….]/30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
interface e 1/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip igmp version 3
© 2013 Cisco and/or its affiliates. All rights reserved.
interface e 1/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip igmp version 3
22
OTV Characteristics
 2-wide 7k Aggregation VDC
 Multi-homed OTV VDC
 Multicast enabled transport
 Extend VLAN 10
Finish OTV Configuration :: Overlay, Site-ID, Site-VLAN
feature otv
feature otv
vlan 10 , 99
vlan 10 , 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10, 99
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10 , 99
interface e2/1, e2/2
channel-group 10 force mode active
Site ID 1
Site VLAN 99
Site ID 1
Site ID 2
Site VLAN 99 Site VLAN 99
Site ID 2
Site VLAN 99
interface e2/1, e2/2
channel-group 10 force mode active
feature otv
feature otv
vlan 10 , 99
vlan 10 , 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10 , 99
© 2013 Cisco and/or its affiliates. All rights reserved.
Step 1 :: enable OTV feature
Step 2 :: configure site-vlan
Step 3 :: enable site-vlan on L2 trunks (make vlan active)
Step 4 :: configure site-identifier
Step 5 :: configure OTV Overlay Interface
interface e2/1, e2/2
channel-group 10 force mode active
interface e2/1, e2/2
channel-group 10 force mode active
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10 , 99
23
NOTES
OTV Configuration



Site ID 1
Site VLAN 99
•
•
•
•

The Layer 2 links are known as internal interfaces and are used by the OTV edge device to learn the
MAC addresses of the site and forward Layer 2 traffic across the sites for the extended VLANs.
The Layer 3 link is known as the join interface, which OTV uses to perform IP-based virtualization to
send and receive overlay traffic between sites. The IP address of this interface is used to advertise
reachability of a MAC addresses present in the site. There is one Join interface per OTV Overlay;
however, if multiple Layer 3 interfaces are present on the OTV edge device, the unicast extended traffic
can get routed over any of these links
OTV encapsulates packets into an IP header and where it sets the Don't Fragment (DF) bit for all OTV
control and data packets crossing the transport network. The encapsulation adds 42 bytes to the original
IP maximum transition unit (MTU) size. So it is a best practice to configure the join interface and all
Layer 3 interfaces that face the IP core between the OTV edge devices with the max possible MTU size
supported by the transport.
OTV uses site VLAN to allow multiple OTV edge devices within the site to talk to each other and
determine the AED for the OTV-extended VLANs. It is a best practice to use a dedicated VLAN as site
VLAN. The site VLAN should not be extended and should be carried down to the aggregation layer
across the VPC peer link.
The OTV edge device is also configured with the overlay interface, which is
associated with the join interface to provide connectivity to the physical
transport network. The overlay interface is used by OTV to send and receive
Layer 2 frames encapsulated in IP packets. From the perspective of MACbased forwarding on the site, the overlay interface is simply another bridged
interface. However, no Spanning Tree Protocol packets or unknown unicast
packets are forwarded over the overlay interface.
Note: The overlay interface does not come up until you configure a multicast
group address and the site-VLAN has at least an active port on the device.
A VLAN is not advertised on the overlay network; therefore, forwarding
cannot occur over the overlay network unless the VLANs are explicitly
extended. Once the VLAN is extended, the OTV edge device will begin
advertising locally learned MAC addresses on the overlay network.
Key advantages of using multicast is that it allows optimal multicast traffic
replication to multiple sites and avoids head-end replication that leads to
suboptimal bandwidth utilization.
© 2013 Cisco and/or its affiliates. All rights reserved.
•
•
•
•
When sites are multihomed with OTV EDs, separation is achieved by electing
an authoritative edge device (AED) for each VLAN in the same site (site-id),
which is the only device that can forward the traffic for the extended VLAN
inside and outside the data center. The extended VLANs are split in odd and
even and automatically assigned to the site's edge devices.
The multicast control group identifies the overlay; two different overlays must
have two different multicast control groups. The control group is used for
neighbor discovery and to exchange MAC address reachability. The data
group however is an SSM (Source Specific Group) group range, which is
used to carry multicast data traffic generated by the sites
In the aggregation layer, Protocol Independent Multicast (PIM) is configured
on all intra- and inter-data-center Layer 3 links to allow multicast states to be
built in the core network.
Since PIM sparse mode requires a rendezvous point (RP) to build a multicast
tree, one of the aggregation switches in each data center is used as an RP.
Local RP allows both local sources and receivers to join local RP rather than
having to go to different data center to reach an RP in order to build a shared
tree. For more information about MSDP and Anycast features of multicast,
visit: http://www.cisco.com/en/US/docs/ios/solutions_docs/ip_multicast/White_papers/anycast.html
24
Primary Adjacency Server :: Join Interface [x]
Secondary Adjacency Server :: Join Interface [y]
OTV Configuration :: Unicast-Only Mode
Primary Adjacency Server
Secondary Adjacency Server
feature otv
feature otv
vlan 10, 99
vlan 10, 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv adjacency-server unicast-only
otv extend-vlan 10
interface Overlay 1
otv join-interface ethernet 1/9
otv adjacency-server unicast-only
otv use-adjacency-server [x] unicast-only
otv extend-vlan 10
interface e 1/9
mtu 9216
ip address [x] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
Site ID 1
Site VLAN 99
Site ID 1
Site ID 2
Site VLAN 99 Site VLAN 99
interface e 1/9
mtu 9216
ip address [y] / 30
Site ID 2
ip router ospf 1 area 0.0.0.0
Site VLAN 99 ip ospf network point-to-point
feature otv
feature otv
vlan 10, 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
vlan 10, 99
Step 1 :: enable OTV
Step 2 :: configure site-vlan, site-id, Overlay Interface
Step 3 :: define role of adjacency server [primary]
Step 4 :: define role of adjacency server [secondary]
Step 5 :: define all other edge devices as clients
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv use-adjacency-server [x] [y] unicast-only
otv extend-vlan 10
Assume :: enable site-vlan on L2 trunks (make vlan active)
interface Overlay 1
otv join-interface ethernet 1/9
otv use-adjacency-server [x] [y] unicast-only
otv extend-vlan 10
interface e 1/9
mtu 9216
ip address [w] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface port-channel 10
switchport
switchport mode trunk
switchport trunk allowed vlan 10, 99
interface e 1/9
mtu 9216
ip address [z] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
© 2013 Cisco and/or its affiliates. All rights reserved.
25
NOTES
OTV Configuration :: Unicast-Only Mode
Primary Adjacency Server
Secondary Adjacency Server
feature otv
feature otv
vlan 10, 99
vlan 10, 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv adjacency-server unicast-only
otv extend-vlan 10
interface Overlay 1
otv join-interface ethernet 1/9
otv adjacency-server unicast-only
otv use-adjacency-server [x] unicast-only
otv extend-vlan 10
interface e 1/9
mtu 9216
ip address [x] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
interface e 1/9
mtu 9216
ip address [y] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
feature otv
vlan 10, 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface ethernet 1/9
otv use-adjacency-server [x] [y] unicast-only
otv extend-vlan 10
interface e 1/9
mtu 9216
ip address [w] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
© 2013 Cisco and/or its affiliates. All rights reserved.
Primary Adjacency Server :: Join Interface [x]
Secondary Adjacency Server :: Join Interface [y]
Two pieces of configuration are required to deploy OTV across a unicast-only transport infrastructure: first, it
is required to define the role of Adjacency Server; whereas the other piece of configuration is required in
each OTV edge device not acting as an Adjacency Server (i.e acting as a client). All client OTV edge devices
are configured with the address of the Adjacency Server. All other adjacency addresses are discovered
dynamically. Thereby, when a new site is added, only the OTV edge devices for the new site need to be
configured with the Adjacency Server addresses. No other sites need additional configuration.
The recommendation is usually to deploy a redundant pair of Adjacency Servers in separate DC sites.
The configuration on the Primary Adjacency Server is very simple and limited to enable AS functionality (otv adjacencyserver command). The same command is also required on the Secondary Adjacency Server device, but also needs to
point to the Primary AS (leveraging the otv use-adjacency-server command). Finally, the generic OTV Edge Device
must be configured to use both the Primary and Secondary Adjacency Servers. The sequence of adjacency server
address in the configuration determine primary or secondary adjacency server role. This order is relevant since an OTV
edge device will always use the OTV neighbor-list (oNL) provided by the Primary Adjacency Server, unless it detects that
specific device is not available anymore (control plane Hellos are always exchanged as keepalives between each OTV
device and the Adjacency Servers).
26
Step 1 :: create OTV HSRP access-lists (VACL)
Step 2 :: create OTV HSRP localization filters
Filter out HSRP v1 and v2
Filter out Gratuitous ARP
Step 3 :: create route-map to prevent advertisements of HSRP VMACs
OTV Configuration :: HSRP Filtering
ip access-list ALL_IPs
10 permit ip any any
mac access-list ALL_MACs
10 permit any any
ip access-list HSRP_IP
10 permit udp any 224.0.0.2/32 eq 1985
20 permit udp any 224.0.0.102/32 eq 1985
mac access-list HSRP_VMAC
10 permit 0000.0c07.ac00 0000.0000.00ff any
20 permit 0000.0c9f.f000 0000.0000.0fff any
arp access-list HSRP_VMAC_ARP
10 deny ip any mac 0000.0c07.ac00 ffff.ffff.ff00
20 deny ip any mac 0000.0c9f.f000 ffff.ffff.f000
30 permit ip any mac any
feature dhcp
ip arp inspection filter HSRP_VMAC_ARP vlan 10
feature otv
vlan 10, 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
otv-isis default
vpn Overlay1
redistribute filter route-map OTV_HSRP_filter
vlan access-map HSRP_Localization 10
match mac address HSRP_VMAC
match ip address HSRP_IP
action drop
vlan access-map HSRP_Localization 20
match mac address ALL_MACs
match ip address ALL_IPs
action forward
vlan filter HSRP_Localization vlan-list 10
mac-list OTV_HSRP_VMAC_deny seq 10 deny 0000.0c07.ac00 ffff.ffff.ff00
mac-list OTV_HSRP_VMAC_deny seq 11 deny 0000.0c9f.f000 ffff.ffff.f000
mac-list OTV_HSRP_VMAC_deny seq 20 permit 0000.0000.0000 0000.0000.0000
route-map OTV_HSRP_filter permit 10
match mac-list OTV_HSRP_VMAC_deny
© 2013 Cisco and/or its affiliates. All rights reserved.
The filtering of FHRP messages across the overlay is a
critical functionality to be enabled, because it allows
applying the same FHRP configuration in different sites.
The end result is that the same default gateway is
available (i.e. characterized by the same virtual IP and
virtual MAC addresses) in each data center. This
capability optimizes the outbound traffic flows (server to
client direction); but this does not solve the mechanism
to control and improve the ingress traffic (client to server
direction) as traffic will continue to go via the original DC;
solutions to solve this challenge include DNS Based,
Route Injection, or LISP.
The VLAN ACL is required to identify the traffic that
needs to be filtered. This configuration applies to the
HSRP v1 & v2 (bold) protocols. After applying the
configuration on the OTV VDC to the set of VLANs that are trunked from the Agg
VDC to the OTV VDC, all HSRP messages will be dropped once received by the OTV
VDC. It is also required to apply a specific filter to ensure suppression of the
Gratuitous ARP (GARP) messages that may be received across the OTV Overlay
from the remote sites.
Even though HSRP traffic is filtered via the VACL, the vMAC used to source the
HSRP packets is still learned by the OTV VDC. Therefore, OTV advertises this MAC
address information to the other sites via an IS-IS update. While this in itself is not
causing harm, it would cause the remote OTV the edge devices to see constant MAC
moves happening for the vMAC (from the internal interface to the overlay interface
and vice versa).





IP ACL's to drop HSRP Hellos and forward other traffic
MAC ACL's to drop non-IP HSRP traffic and forward other traffic
Create the VACL & apply the VACL to each extended vlan
Feature dhcp required for ARP inspection & create the ARP access-list to deny
traffic from the Virtual MAC & apply ARP ACL to each extended VLAN
mac-list to deny advertising virtual MAC, create the route-map, and apply the
route-map to each overlay
27
Perform Configuration Steps at
Both DC Sites (East & West)
OTV Configuration :: Authentication
OTV supports authentication of Hello messages along with
authentication of Protocol Data Units (PDU)’s
feature otv
feature otv
vlan 10, 99
vlan 10, 99
key chain OTV-Key
key 1
key-string 0 Cisc0!
key chain OTV-Key
key 1
key-string 0 Cisc0!
otv site-vlan 99
otv site-identifier 0000.0000.0001
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
otv isis authentication-type md5
otv isis authentication key-chain OTV-Key
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
otv isis authentication-type md5
otv isis authentication key-chain OTV-Key
otv-isis default
vpn Overlay1
authentication-check
authentication-type md5
authentication key-chain OTV-Key
© 2013 Cisco and/or its affiliates. All rights reserved.
Step 1 :: configure OTV key chain
Step 2 :: apply md5 authentication to OTV Hellos
Step 3 :: apply md5 authentication to OTV PDUs
otv-isis default
vpn Overlay1
authentication-check
authentication-type md5
authentication key-chain OTV-Key
28
Perform Configuration Steps at
Both DC Sites (East & West)
OTV Configuration :: Logical Join Interface
feature otv
feature ospf
feature pim
vlan 10, 99
router ospf 1
ip pim rp-address [x.x.x.x] group-list 224.0.0.0/4
ip pim ssm range 232.0.0.0/8
interface loopback 10
ip address [….]/32
ip router ospf 1 area 0
ip pim sparse-mode
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface loopback 10
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
interface e 1/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
interface e 2/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip pim sparse-mode
© 2013 Cisco and/or its affiliates. All rights reserved.
Overlay can now use otv source-interface command to
source OTV traffic from the edge device and source joins to
receive multicast traffic from the core. Loopback to guarantee
interface is up/up.
Multiple L3 uplinks can now connect to OTV edge device, each
running PIM and an IGP with IPv4 Core. The OTV edge device
can now act as first-hop/last-hop multicast PIM router instead
of IGMP client; “ip pim sparse-mode” on all L3 interfaces.
Old Configuration
(OTV Join Interface)
interface e 1/9
mtu 9216
ip address [….] / 30
ip router ospf 1 area 0.0.0.0
ip ospf network point-to-point
ip igmp version 3
Existing Join Interface limitations:
 Bandwidth to the core / aggregation is limited to
Step 1 :: enable PIM
one physical link or port-channel
Step 1 :: configure loopback interface
 Changes to join-interface will churn all OTV
Step 4 :: configure Rendezvous Point (RP)
overlay states, since the overlay encapsulation for
Step 5 :: configure Source-Specific Multicast (SSM)
all routes need to be updated
Step 2 :: set OTV joint interface as loopback
 PIM cannot be enabled on the join-interface, since
Step 3 :: enable PIM sparse on loopback
the OTV solution assumes it's an IGMP host
Step 4 :: enable PIM sparse on all L3 links
interface
 Unable to utilize the redundancy of multiple uplinks
when available, and the flexibility of dynamic
unicast routing convergence on uplink failures
Note: OTV Tunnel depolarization will be introduced in a

If join-interface goes down, the connectivity to the
future release. The use of a secondary IP address on
core is broken. User intervention is needed to
the interface, not the OTV interface, will help improve
provide alternate core connectivity
load balancing ECMP for OTV traffic to the core.
29
OTV VLAN Translation :: Translation Through Transit VLAN
feature otv
feature otv
vlan 10, 99, 100
vlan 20, 99, 100
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
otv vlan mapping 10 to 100
Step 1 :: configure vlan mapping




When a different VLAN is used at multiple sites
A mapped VLAN can not be extended on another site
VLAN mappings have a one-to-one relationship
VLAN mappings can be added or removed without
impacting all mappings on the overlay interface
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 20
otv vlan mapping 20 to 100
VLAN 20
VLAN 100
VLAN 10
© 2013 Cisco and/or its affiliates. All rights reserved.
30
Perform Configuration Steps at
Both DC Sites (East & West)
OTV Configuration :: Dedicated Broadcast Group




“otv broadcast-group” configuration line under overlay
Optional command
Useful for QoS purposes
The broadcast group needs to be configured for all OTV
Edge Devices connected to the OTV Overlay network
feature otv
feature otv
vlan 10, 99
vlan 10, 99
interface loopback 10
ip address [….]/32
interface loopback 10
ip address [….]/32
Step 1 :: configure broadcast group
otv site-vlan 99
otv site-identifier 0000.0000.0001
otv site-vlan 99
otv site-identifier 0000.0000.0001
interface Overlay 1
otv join-interface loopback 10
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv broadcast-group 224.2.2.0
otv extend-vlan 10
otv vlan mapping 10
interface Overlay 1
otv join-interface loopback 10
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv broadcast-group 224.2.2.0
otv extend-vlan 10
otv vlan mapping 10
© 2013 Cisco and/or its affiliates. All rights reserved.
31
OTV Configuration :: Selective Unicast Flooding
feature otv
feature otv
vlan 10, 99
vlan 10, 99
otv site-vlan 99
otv site-identifier 0000.0000.0001
Step 1 :: configure static OTV flood
[enabled per mac address]
otv flood mac 1111.2222.0101 vlan 10
otv site-vlan 99
otv site-identifier 0000.0000.0002
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
interface Overlay 1
otv join-interface ethernet 1/9
otv control-group 239.1.1.1
otv data-group 232.1.1.0/24
otv extend-vlan 10
Unknown
Unicast
MAC 1  MAC 2
Normally, unknown unicast Layer 2 frames are not flooded between OTV sites, and MAC addresses are not learned across the overlay interface. Any unknown unicast
messages that reach the OTV edge device are blocked from crossing the logical overlay, allowing OTV to prevent Layer 2 faults from spreading to remote sites.
The end points connected to the network are assumed to not be silent or unidirectional. However, some data center applications require the unknown unicast traffic to
be flooded over the overlay to all the data centers, where end points may be silent. Beginning with Cisco NX-OS Release 6.2(2), you can configure selective unicast
flooding to flood the specified destination MAC address to all other edge devices in the OTV overlay network with that unknown unicast traffic.
© 2013 Cisco and/or its affiliates. All rights reserved.
32
Strong Recommendations and Key Notes
 OTV encapsulation is done on M-series modules
 Note: The control-plane protocol used by OTV is IS-IS. However, IS-IS does not need to be explicitly configured. It runs in
the background once OTV is enabled.
 In a multi-tenancy environment, the same OTV VDC can be configured with multiple overlays to provide a segmented
Layer 2 extension for different tenants or applications.
 When multiple data center sites are interconnected, the OTV operations can benefit from the presence of multicast in the
core. Multicast is not mandatory in most OTV topologies (number of sites) since you can use the unicast-mode as well.
 The same OTV VDCs can be used by multiple VDCs deployed at the aggregation tier, as well as by other Layer 2 switches
connected to the OTV VDCs. This is done by configuring multiple OTV overlays. It's important to note that the extended
VLANs within these multiple overlays should not overlap.
 A separate Layer 3 link between the two aggregation VDCs should be configured as per best practices to carry any Layer
3 traffic between the them.
 The overlay interface will not come up until you configure a multicast group address and the site-VLAN has at least an
active port on the OTV edge device.
 Support for loopback interfaces as OTV Join interfaces is planned for 6.2(2) and later code releases.
© 2013 Cisco and/or its affiliates. All rights reserved.
33
Strong Recommendations and Key Notes
 FHRP Filtering Note: It is important to stress how this outbound path (server to client) optimization functionality should be
deployed in conjunction with an equivalent one optimizing inbound traffic (client to server) flows to avoid asymmetric traffic
behavior (this would be highly undesirable especially in deployments leveraging stateful services across data centers).
White Paper discussing inbound traffic optimization solutions ::
http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/4.0/EMC/EMC.pdf
 It is important to note how OTV support requires the use of the new Transport Services (TRS) license. Depending on the
specifics of the OTV deployment, the Advanced License may be required as well to provide Virtual Device Contexts
(VDCs) support.
 Before configuring OTV you should review and implement Cisco recommended STP best practices at each site. OTV is
independent from STP but it greatly benefits from a stable and robust Layer 2 topology.
 If the data centers are OTV multi-homed, it is a recommended best practice to bring the Overlay up in single-homed
configuration first, by enabling OTV on a single edge device at each site. After the OTV connection has been tested in as
single-homed, then enable the functionality on the other edge devices of each site.
 OTV currently enforces switch-virtual-interface (SVI) separation for the VLANs being extended across the OTV link,
meaning that OTV is usually in its own VDC. With the VDC license on the Cisco Nexus 7000 you have the flexibility to
have SVIs in other VDCs and have a dedicated VDC for OTV functions.
 Configure the join interface and all Layer 3 interfaces that face the IP core between the OTV edge devices with the highest
maximum transmission unit (MTU) size supported by the IP core. OTV sets the Don't Fragment (DF) bit in the IP header
for all OTV control and data packets so the core cannot fragment these packets.
© 2013 Cisco and/or its affiliates. All rights reserved.
34
Strong Recommendations and Key Notes
 With NX-OS 6.1 and earlier: Only one join interface can be specified per overlay; two methods are available
Configure a single join-interface, which is shared across multiple overlays
Configure a different join interface for each overlay, which increases the OTV reliability
 For a higher resiliency, you can use a port-channel, but it is not mandatory. There are no requirements for 1 GigabitEthernet versus 10 Gigabit-Ethernet or dedicated versus shared mode.
 The transport network must support PIM sparse mode (ASM) or PIM-Bidir multicast traffic.
 OTV is compatible with a transport network configured only for IPv4. IPv6 is not supported.
 Do not enable PIM on the join-interface.
 Do not configure OTV on an F-series module.
 Ensure the site identifier is configured and is the same for all edge devices on a site. OTV brings down all overlays when a
mismatched site identifier is detected from a neighbor edge device and generates a system message.
 Mixing the Nexus 7000 and the ASR 1000 devices for OTV is not supported at this time when the devices will be placed
within the same site. However, using Cisco Nexus 7000s in one site and Cisco ASR 1000s at another site for OTV is fully
supported. For this scenario, please keep the separate scalability numbers in mind for the two different devices, because
you will have to account for the lowest common denominator.
 Starting in NX-OS 5.2, the site-id command was introduced as a way to harden multihoming for OTV. It is a configurable
option that must be the same for devices within the same data center and different between any devices that are in
different data centers. It specifies which site a particular OTV device is in so that two OTV devices in different sites cannot
join each other as a multihomed site. This command is now mandatory.
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35
Strong Recommendations and Key Notes
 Using Virtual Port Channels (vPCs) and OTV together provides an extra layer of resiliency and is thus recommended as a
best practice.
 OTV & FabricPath: Because OTV encapsulation is done on M-series modules, OTV cannot read FabricPath packets.
Because of this restriction, terminating FabricPath and reverting to Classical Ethernet where the OTV VDC resides is
necessary. In addition, when running FabricPath in your network, we highly recommend that you use the spanning-tree
domain <id> command on all devices that are participating in these VLANs. This command speeds up convergence times
greatly.
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36
OTV Encapsulation :: MAC in IP
• 42 Bytes overhead to the packet IP MTU size
(Outer IP Header + OTV Shim) – (Original L2 Header without the 802.1Q header)
• 802.1Q header is removed and the VLAN field copied over to the OTV shim header
• Outer OTV shim header contains VLAN, overlay ID number, and an external IP header
• Consider Jumbo MTU Sizing along the path between the source and destination endpoints to account for the extra 42 bytes
802.1Q header removed
802.1Q
802.1Q
SMAC
6B
6B
2B
IP Header
20B
Ether
Type
SMAC
OTV Shim
VLAN
DMAC
Ether
Type
DMAC
8B
L2
Header
14B*
CRC
Payload
4B
Original L2 Frame
20B + 8B + 14B* = 42 Bytes
of total overhead
* The 4 Bytes of the 802.1Q header have already been removed
© 2013 Cisco and/or its affiliates. All rights reserved.
37
How OTV Works :: Inter-Site Packet Flow (OTV Data Plane)
MAC Table
MAC Table
VLAN
MAC
IF
10
MAC 1
Eth 1
10
MAC 2
IP B
10
MAC 3
Eth 3
Layer 2
Lookup
Layer 2
Lookup
WEST DC
MAC
IF
10
MAC 1
IP A
10
MAC 2
Eth 2
10
MAC 3
IP A
EAST DC
Encap
MAC 1  MAC 2
VLAN
Decap
IP A  IP B
MAC 1  MAC 2
MAC 1  MAC 2
IP A  IP B
MAC 1  MAC 2
Assumption :: New MACs where learned in the VLANs that are OTV extended on the internal interfaces; an OTV update message was sent and replicated across the
transport and delivered to all remote OTV Edge devices; those MACs learned through OTV are then imported in the MAC address tables of the OTV Edge Devices.
Step 1 :: The Layer 2 frame is received at the aggregation layer or OTV Edge Device. A traditional Layer 2 lookup is performed, the MAC for Host B’s information in the
MAC table does not point to a local Ethernet interface (as you would see in intra-site communication); but to the IP address of the remote OTV Edge Device that
advertised that MAC’s reachability information.
Step 2 :: The OTV Edge Device encapsulates the original Layer 2 Frame; with is the source IP of the outer header of the local Join interface & the destination IP which is
the IP address of the remote Edge Device Join interface.
Step 3 :: The OTV encapsulated frame (a regular unicast IP packet) is carried across the transport infrastructure and delivered to the remote OTV Edge Device.
Step 4 :: The remote OTV Edge Device decapsulates the frame exposing the original Layer 2 packet.
Step 5 :: The OTV Edge Device performs another Layer 2 lookup on the original Ethernet frame and discovers that it is reachable through a physical interface, which
means it is a MAC address local to the site.
Step 6 :: The frame is then delivered to the MAC destination of Host B
© 2013 Cisco and/or its affiliates. All rights reserved.
38
Additional Resources & Further Reading
External (public)
OTV Best Practices Guide
http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/guide_c07-728315.pdf
Great External
Resources
OTV Technology Introduction and Deployment Considerations
http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI_1.html
Using OTV to Extend Layer 2 between Two Data Centers
http://www.cisco.com/en/US/prod/collateral/switches/ps9441/ps9402/white_paper_c11-644634.html
Nexus 7000 NX-OS OTV Configuration Guides
http://www.cisco.com/en/US/docs/switches/datacenter/sw/nx-os/OTV/config_guide/b_Cisco_Nexus_7000_Series_NXOS_OTV_Configuration_Guide.html
Cisco Nexus 7000 NX-OS Verified Scalability Guide (OTV Limits)
http://www.cisco.com/en/US/docs/switches/datacenter/sw/verified_scalability/b_Cisco_Nexus_7000_Series_NXOS_Verified_Scalability_Guide.html#reference_18192F87114B45D9A40A41A0DEF3F74D
Cisco Live 365 (sign up & search session catalog for OTV)
https://ciscolive365.com/
BRKDCT – 3103 :: Advance OTV – Configure, Verify and Troubleshoot OTV in Your Network; Andy Gossett (CSE)
© 2013 Cisco and/or its affiliates. All rights reserved.
39
Additional Resources & Further Reading
Quick Start Guide :: Virtual Port Channel (vPC)
https://communities.cisco.com/docs/DOC-35728
Quick Start Guide :: FabricPath
https://communities.cisco.com/docs/DOC-35725l
© 2013 Cisco and/or its affiliates. All rights reserved.
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© 2013 Cisco and/or its affiliates. All rights reserved.
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