1. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 1 Silent Host Connectivity Problem OTV assumes that there are no silent or unidirectional devices: http://www.cisco.com/en/US/docs/solutions/Enterprise/Data_Center/DCI/whitepaper/DCI_1.html#wp1185931 There are several scenarios where a silent host can cause connectivity issues. The purpose of this document is to show why traffic loss occurs during an AED failover. There are several scenarios where a silent host can cause connectivity issues. The purpose of this document is to show why traffic loss occurs during an AED failover. Note that any type of broadcast/unicast flooded packet sourced from the silent host that reaches the AED will resolve the issue. Note that any type of broadcast/unicast flooded packet sourced from the silent host that reaches the AED will resolve the issue.

2. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 2 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Physical View Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 4948-2 10.0.0.102 c84c.75f6.283f 4948-1 10.0.0.101 c84c.75f6.013f AED

3. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 3 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED S1-OTV-2# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:00:27 overlay S2-OTV-1 10 c84c.75f6.283f 1 00:01:36 site port-channel102 S1-OTV-2# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:00:27 overlay S2-OTV-1 10 c84c.75f6.283f 1 00:01:36 site port-channel102 S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:00:36 site Ethernet10/13 10 c84c.75f6.283f 42 00:01:44 overlay S1-OTV-2 S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:00:36 site Ethernet10/13 10 c84c.75f6.283f 42 00:01:44 overlay S1-OTV-2 Continuous pings to 4948-2 Silent Host Failover

4. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 4 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED S1-OTV-2 VDC is shut down. It takes a few seconds to reconverge and S1-OTV-1 to become AED. During this time packets are dropped. Failing pings to 4948-2

5. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 5 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:01:55 site Ethernet10/13 S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:01:55 site Ethernet10/13 S1-OTV-1 takes over as AED but it does not have Host-2’s MAC in its CAM. Without the MAC in the CAM it cannot advertise the route to S2-OTV-1. S1-OTV-1 will not advertise an OTV route until it sees a packet from Host-2 and the source MAC is added it to its CAM table. Host-2 is a ‘silent host’ and traffic sent to this device from S2-OTV- 1 will be dropped. AED Failing pings to 4948-2 S1-OTV-1# show mac add vlan 10 Legend: * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC age - seconds since last seen,+ - primary entry using vPC Peer-Link VLAN MAC Address Type age Secure NTFY Ports/SWID.SSID.LID ---------+-----------------+--------+---------+------+----+------------------ O 10 c84c.75f6.013f dynamic 0 F F Overlay0 S1-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:01:02 overlay S2-OTV-1 S1-OTV-1# show mac add vlan 10 Legend: * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC age - seconds since last seen,+ - primary entry using vPC Peer-Link VLAN MAC Address Type age Secure NTFY Ports/SWID.SSID.LID ---------+-----------------+--------+---------+------+----+------------------ O 10 c84c.75f6.013f dynamic 0 F F Overlay0 S1-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:01:02 overlay S2-OTV-1

6. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 6 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:03:47 site Ethernet10/13 10 c84c.75f6.283f 42 00:00:04 overlay S1-OTV-1 S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:03:47 site Ethernet10/13 10 c84c.75f6.283f 42 00:00:04 overlay S1-OTV-1 Generate traffic from Host-2, such as a broadcast or ping packet. S1-OTV-1 learns Host-2 source MAC, programs it into its OTV route table and advertises it to S2-OTV-1. S2-OTV-1 OTV mac- routing table points to S1-OTV-1 and connectivity is restored. AED Continuous pings to Host-2 S1-OTV-1# show mac add vlan 10 Legend: * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC age - seconds since last seen,+ - primary entry using vPC Peer-Link VLAN MAC Address Type age Secure NTFY Ports/SWID.SSID.LID ---------+-----------------+--------+---------+------+----+------------------ O 10 c84c.75f6.013f dynamic 0 F F Overlay0 * 10 c84c.75f6.283f dynamic 0 F F Po101 S1-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:03:05 overlay S2-OTV-1 10 c84c.75f6.283f 1 00:00:05 site port-channel101 S1-OTV-1# show mac add vlan 10 Legend: * - primary entry, G - Gateway MAC, (R) - Routed MAC, O - Overlay MAC age - seconds since last seen,+ - primary entry using vPC Peer-Link VLAN MAC Address Type age Secure NTFY Ports/SWID.SSID.LID ---------+-----------------+--------+---------+------+----+------------------ O 10 c84c.75f6.013f dynamic 0 F F Overlay0 * 10 c84c.75f6.283f dynamic 0 F F Po101 S1-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:03:05 overlay S2-OTV-1 10 c84c.75f6.283f 1 00:00:05 site port-channel101 Send a ping to Host-1

7. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 7 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED Non-Silent Host (two hosts sending traffic) S1-OTV-2# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.283f 1 00:06:44 site port-channel102 10 c84c.75f6.013f 42 00:06:14 overlay S2-OTV-1 S1-OTV-2# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.283f 1 00:06:44 site port-channel102 10 c84c.75f6.013f 42 00:06:14 overlay S2-OTV-1 S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.283f 42 00:06:25 overlay S1-OTV-2 10 c84c.75f6.013f 1 00:12:22 site Ethernet10/13 S2-OTV-1# show otv route vlan 10 OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.283f 42 00:06:25 overlay S1-OTV-2 10 c84c.75f6.013f 1 00:12:22 site Ethernet10/13 Continuous pings to Host-2 Continuous pings to Host-1

8. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 8 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED S1-OTV-2 VDC is shut down. It takes a few seconds to reconverge and for S1-OTV-1 to become the AED for Site 1. During this time packets are dropped. Failing pings to Host-2 Failing pings to Host-1

9. © 2010 Cisco and/or its affiliates. All rights reserved. Cisco ConfidentialPresentation_ID 9 S2- OTV-1 S1- OTV-1 Extended Vlan 10 S1- OTV-2 Po101Po102 Po64 G1/47 E10/13 E10/14 E2/17 Host-2 10.0.0.102 c84c.75f6.283f Host-1 10.0.0.101 c84c.75f6.013f AED Since host-2 is still trying to send packets to host-1. S1-OTV-1 learns host-2 MAC, updates its OTV route table and advertises the route to S2-OTV-1. Only a brief outage is seen while S1-OTV-1 transitions to AED. AED S1-OTV-2# show otv route OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:01:15 overlay S2-OTV-1 10 c84c.75f6.283f 1 00:00:32 site port-channel102 S1-OTV-2# show otv route OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 42 00:01:15 overlay S2-OTV-1 10 c84c.75f6.283f 1 00:00:32 site port-channel102 S2-OTV-1# show otv route OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:17:50 site Ethernet10/13 10 c84c.75f6.283f 42 00:00:31 overlay S1-OTV-1 S2-OTV-1# show otv route OTV Unicast MAC Routing Table For Overlay0 VLAN MAC-Address Metric Uptime Owner Next-hop(s) ---- -------------- ------ -------- --------- ----------- 10 c84c.75f6.013f 1 00:17:50 site Ethernet10/13 10 c84c.75f6.283f 42 00:00:31 overlay S1-OTV-1 Continuous pings to Host-2 Continuous pings to Host-1