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VLAN traffic span across vpc peer-link

Mukund Sandur
Level 1
Level 1

Hi,

I have pair of 5596 switches in vPC. One host say "HOST A" is connected to the primary vPC peer and other "HOST B" on secondary vPC peer.

Both are in same VLAN 10. Both hosts are vpc orphan ports as their NIC is configured in active/standby mode.I have configured span session on both vPC peers with span source as VLAN 10 in rx mode.

Span destination is connected to secondary vPC peer. The issue here is that I am not able to capture the traffic originating from HOST A destined to HOST B which is traversing vPC peer-link.

Same issue occurs for the traffic in reverse way and span destination on primary vPC peer. In a nutshell, any traffic which crosses vPC peer-link is not getting captured.

What could be the issue and is there any solution for it. Below mentioned is the span config and relevant interfaces. Also attaching the diagram for reference.

Primary vPC peer span related config:

interface Ethernet1/39

  desc *** SPAN Destination ***
  switchport monitor
  spanning-tree port type edge
  speed 1000

interface Ethernet1/40

  desc *** HOST A ***
  switchport access vlan 10
  spanning-tree port type edge
  speed 1000

monitor session 1

  source vlan 10

  destination interface Ethernet1/39

  no shut

Secondary vPC peer span related config:

interface Ethernet1/39

  desc *** SPAN Destination ***
  switchport monitor
  spanning-tree port type edge
  speed 1000

interface Ethernet1/40

  desc *** HOST B ***
  switchport access vlan 10
  spanning-tree port type edge
  speed 1000

monitor session 1

  source vlan 10

  destination interface Ethernet1/39

  no shut

1 Accepted Solution

Accepted Solutions

Reza Sharifi
Hall of Fame
Hall of Fame

Hi,

If I am looking at your config correctly, you are monitoring e1/39 and you also sending it to e1/39

destination interface Ethernet1/39

The destination should be e1/40 where the PC is connected to.

HTH

View solution in original post

4 Replies 4

Reza Sharifi
Hall of Fame
Hall of Fame

Hi,

If I am looking at your config correctly, you are monitoring e1/39 and you also sending it to e1/39

destination interface Ethernet1/39

The destination should be e1/40 where the PC is connected to.

HTH

Hi Reza,

I have two hosts A & B which are communicating to each other and they are connected to e1/40 on their respective switches. These hosts are shown in the diagram.

The third PC where I am running wireshark is connected to e1/39 which is the span destination configured in the monitor session. I simply shift the third machine when I want to span the traffic on the respective switches.

Thanks & Rgds,

Mukund Sandur

Hi,

Sorry, the diagram got me confused since I didn't see port e1/39 in it.

What happens when you try monitoring the 1/47 or 1/48 (vPC peer link)?

HTH

Hi Reza,

Even if I montior the vPC peer link, I am not able to span the traffic crossing the peer-link

only when I monitor the host interface ie e1/40 (tx & rx), then I am able to span the traffic coming via vPC peer-link

Thanks & Rgds,

Mukund Sandur

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