OTV adjacency is formed across the layer 3 multicast clouds by exchanging L1 ISIS Hello packets.
Sample Topology
1. Verify IGMP V3 Join
After the OTV configuration completed, enabling the join interface sends any source IGMP v3 join on that interface.
SITE1-OED1# show run int eth 1/31
interface Ethernet1/31
description [OTV-JOIN-INTERFACE]
vrf member OTV
ip address 10.10.15.6/30
ip router eigrp 10
ip igmp version 3
SITE1-OED1(config-if)# int eth 1/31
SITE1-OED1(config-if)# no shut
SITE1-AGG1%OTV# show ip mroute
IP Multicast Routing Table for VRF "OTV"
(*, 239.1.1.1/32), uptime: 0.283775, igmp pim
Incoming interface: Ethernet1/5, RPF nbr: 10.10.15.1 <<< Interface facing Multicast RP
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 0.283711, igmp <<< Interface connecting to OTV VDC SITE1-OED1
2. Verify ISIS Hello Packets
When you enable the OTV overlay interface, the switch will generate a L1 ISIS hello packet with the source IP address as the OTV join interface and the destination IP address as the OTV control-group.
SITE1-AGG1%OTV# show ip mroute
IP Multicast Routing Table for VRF "OTV"
(*, 239.1.1.1/32), uptime: 00:16:00, igmp pim ip
Incoming interface: Ethernet1/5, RPF nbr: 10.10.15.1
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 00:16:00, igmp
(10.10.15.6/32, 239.1.1.1/32), uptime: 00:00:19, ip mrib pim <<< S,G entry represents Mcast packet received from 10.10.15.6
Incoming interface: Ethernet1/9, RPF nbr: 10.10.15.6
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 00:00:19, mrib, (RPF)
3. Verify Multicast Transport
After all the four OTV edge devices are configured and enabled, the multicast transport network should show all the sources
SITE1-AGG1%OTV# show ip mroute
IP Multicast Routing Table for VRF "OTV"
(*, 239.1.1.1/32), uptime: 00:23:13, igmp pim ipIncoming interface: Ethernet1/5, RPF nbr: 10.10.15.1
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 00:23:13, igmp
(10.10.15.6/32, 239.1.1.1/32), uptime: 00:07:33, ip mrib pim <<< SITE1-OED1
Incoming interface: Ethernet1/9, RPF nbr: 10.10.15.6
Outgoing interface list: (count: 2)
Ethernet1/5, uptime: 00:05:44, pim
Ethernet1/9, uptime: 00:07:33, mrib, (RPF)
(10.10.16.6/32, 239.1.1.1/32), uptime: 00:04:48, ip mrib pim <<< SITE1-OED2
Incoming interface: Ethernet1/5, RPF nbr: 10.10.15.1
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 00:04:48, mrib
(10.10.17.6/32, 239.1.1.1/32), uptime: 00:04:21, ip mrib pim <<< SITE2-OED1
Incoming interface: Ethernet1/5, RPF nbr: 10.10.15.1
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 00:04:21, mrib
(10.10.18.6/32, 239.1.1.1/32), uptime: 00:03:46, ip mrib pim <<< SITE2-OED2
Incoming interface: Ethernet1/5, RPF nbr: 10.10.15.1
Outgoing interface list: (count: 1)
Ethernet1/9, uptime: 00:03:46, mrib
You can also monitor the OTV control packets statistics as below.
SITE1-AGG1%OTV# show ip mroute summary
IP Multicast Routing Table for VRF "OTV"
Total number of routes: 6
Total number of (*,G) routes: 1
Total number of (S,G) routes: 4
Total number of (*,G-prefix) routes: 1
Group count: 1, rough average sources per group: 4.0
Group: 232.0.0.0/8, Source count: 0
Source packets bytes aps pps bit-rate oifs
(*,G) 0 0 0 0 0.000 bps 0
Group: 239.1.1.1/32, Source count: 4
Source packets bytes aps pps bit-rate oifs
(*,G) 7 10106 1443 0 0.000 bps 1
10.10.15.6 73 86674 1187 0 1349.600 bps 2
10.10.16.6 96 76987 801 0 1429.600 bps 1
10.10.17.6 103 81610 792 0 1416.267 bps 1
10.10.18.6 155 144435 931 0 4092.800 bps 1
4. Verify OTV ISIS Adjacency
You can verify the Adjacency using the below command:
SITE1-OED1# show otv adjacency detail
Overlay Adjacency database
Overlay-Interface Overlay1 :
Hostname System-ID Dest Addr Up Time State
SITE1-OED2 0024.986f.bac4 10.10.16.6 00:05:31 UP
HW-St: Up Peer-ID: 3
SITE2-OED1 0026.51ce.0f43 10.10.17.6 00:46:29 UP
HW-St: Up Peer-ID: 2
SITE2-OED2 0026.51ce.0f44 10.10.18.6 00:46:29 UP
HW-St: Up Peer-ID: 1
5. Troubleshoot OTV ISIS Adjacency
If there is any issue in establishing OTV ISIS adjacency, you can look at the ISIS adjacency log as below:
SITE1-OED1# show otv isis internal event-history adjacency
ISIS default process
adjacency Events for ISIS process
2011 May 21 08:54:53.773678 isis_otv default [10371]: (Overlay1) : LAN adj L1
SITE2-OED1 over Overlay1 - UP
2011 May 21 08:54:53.773662 isis_otv default [10371]: [10376]: Sent OTV add adja
cency for overlay:Overlay1, addr: 10.10.17.6
2011 May 21 08:54:53.653906 isis_otv default [10371]: (Overlay1) : Set adjacency
SITE2-OED1 over Overlay1 IPv4 address to 10.10.17.6
2011 May 21 08:54:53.653827 isis_otv default [10371]: (Overlay1) : LAN adj L1
SITE2-OED1 over Overlay1 - INIT (New)
2011 May 21 08:54:53.653799 isis_otv default [10371]: [10376]: Initialize adj fo
r L1 MT-0 for iib Overlay1
You can clear the log as below:
SITE1-OED1# clear otv isis event-history
6. Verify OTV overlay interface
Verify Overlay interface is up.
SITE1-OED1# show otv
OTV Overlay Information
Overlay interface Overlay1
VPN name : Overlay1
VPN state : UP
Extended vlans : 100-200 (Total:101)
Control group : 239.1.1.1
Data group range(s) : 232.1.1.0/26
Join interface(s) : Eth1/31 (10.10.15.6)
Site vlan : 95 (up) <<< Site VLAN should be Up
Site VLAN should be in spanning tree forwarding on atleast one port in the OTV VDC. If not, the data will not be forwarded across the OTV even though the OTV overlay is up and adjacency is forwarded with other peers.
7. Verify Tunnel Creation
After the OTV adjacency is setup, OTV process creates implicit tunnels for each discovered peer. These tunnels will be used to forward the data across OTV to the respective site.
show otv internal event-history debug
2011 May 21 10:10:58.428388 otv [10358]: [10361]: otv_tunnel_gre_add Tunnel (10.
10.15.6, 10.10.17.6) does not exist, creating NEW
2011 May 21 10:10:58.426206 otv [10358]: [10361]: Received ISIS add adjacency me
ssage for (Overlay1, 10.10.17.6) , sid 0026.51ce.0f43
Tunnel process in the NX-OS creates these tunnels based on the request from OTV process. You can verify the implicit tunnels as below:
SITE1-OED1# show tunnel internal implicit otv brief
-------------------------------------------------------------------------------
Interface Status IP Address Encap type MTU
-------------------------------------------------------------------------------
Tunnel16424 up -- GRE/IP 9178
Tunnel16425 up -- GRE/IP 9178
SITE1-OED1# show tunnel internal implicit otv detail
Tunnel16424 is up
MTU 9178 bytes, BW 9 Kbit
Transport protocol is in VRF "OTV"
Tunnel protocol/transport GRE/IP
Tunnel source 10.10.15.6, destination 10.10.18.6
Last clearing of "show interface" counters never
Tx
0 packets output, 1 minute output rate 0 packets/sec
Rx
0 packets input, 1 minute input rate 0 packets/sec
Tunnel16425 is up
MTU 9178 bytes, BW 9 Kbit
Transport protocol is in VRF "OTV"
Tunnel protocol/transport GRE/IP
Tunnel source 10.10.15.6, destination 10.10.17.6
Last clearing of "show interface" counters never
Tx
0 packets output, 1 minute output rate 0 packets/sec
Rx
0 packets input, 1 minute input rate 0 packets/sec
The below command will shows the mapping between OTV adjacency and implicit tunnel.
SITE1-OED1# show otv internal adjacency
Overlay Adjacency database
Overlay-Interface Overlay1 :
System-ID Dest Addr Adj-State TM_State Up Time Adj-State inAS
0024.986f.bac4 10.10.16.6 default default 00:05:59 UP UP
HW-St: Up Curr-Peer-St: Up, New-Peer_St: Default Peer-ID: 3 N Tunnel16426
0026.51ce.0f43 10.10.17.6 default default 00:46:57 UP UP
HW-St: Up Curr-Peer-St: Up, New-Peer_St: Default Peer-ID: 2 N Tunnel16425
0026.51ce.0f44 10.10.18.6 default default 00:46:58 UP UP
HW-St: Up Curr-Peer-St: Up, New-Peer_St: Default Peer-ID: 1 N Tunnel16424
SITE1-OED1#
