topic Re: VXLAN and RSPAN between branches in Routing and SD-WAN

VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 07:10:14 GMT

I have vxlan between two branches (configured on the asr1002-x) and I wanted to configure rspan between these branches. Can RSPAN vlan work through vxlan configuraton?

Re: VXLAN and RSPAN between branches

Torbjørn — Wed, 14 May 2025 07:34:49 GMT

Hello @dijix1990,

The best tool for the job would be Encapsulated Remote SPAN(ERSPAN). This encapsulates the span traffic in GRE and allows you to route it to where you need it.

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 07:45:32 GMT

I need to span phones traffic from vlan voice to vlan rspan. Record server only one

Re: VXLAN and RSPAN between branches

M02@rt37 — Wed, 14 May 2025 08:55:04 GMT

Hello @dijix1990

RSPAN ? VXLAN replaces traditional VLAN-based forwarding, and RSPAN relies on VLANs to transport mirrored traffic...

ERSPAN should be a solution since it mirros trafic over L3 network

Other way, if you really want to mirror traffic into a vlan and rely on VxLAN to carry it across sites you should create a VxLAN VNI mapped to the same VLAN as the SPAN target VLAN. Mirror traffic into that VLAN locally and ensute that VLAN is bridged acriss sites via VxLAN

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 08:56:10 GMT

Hm can you give an example of create a VxLAN VNI mapped to the same VLAN?

Re: VXLAN and RSPAN between branches

Elliot Dierksen — Wed, 14 May 2025 08:56:46 GMT

@dijix1990 wrote:

I need to span phones traffic from vlan voice to vlan rspan. Record server only one

What kind of recording server are you using? Most of the current ones use a SIP trunk and recording profile instead of a SPAN port.

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 09:07:34 GMT

I tried to use this construction for RSPAN

bridge-domain 103 member vni 6025 member GigabitEthernet0/0/1 service-instance 103 bridge-domain 975 member vni 6035 member GigabitEthernet0/0/1 service-instance 975 interface GigabitEthernet0/0/1 service instance 103 ethernet description RSPAN encapsulation dot1q 103 service instance 975 ethernet description Voice_DHCP encapsulation dot1q 975

Branch 1 - VXLAN - Branch 2

Branch 1 has record server and rspan configuration

monitor session 1 source vlan 975 monitor session 1 destination remote vlan 103

the same Branch 2 has rspan configuration

monitor session 1 source vlan 975 monitor session 1 destination remote vlan 103

but after it I see macflap

May 14 12:03:54.491: %SW_MATM-4-MACFLAP_NOTIF: Host 0077.8df9.b2b0 in vlan 103 is flapping between port Twe1/0/45 and port Po19
May 14 12:03:54.491: %SW_MATM-4-MACFLAP_NOTIF: Host b4a8.b9e8.5fe8 in vlan 103 is flapping between port Po19 and port Po28

Apparently, the mac addresses from site 1 that are packed into vlan103 after vxlan are unpacked for some reason

sh mac add vlan 103 Mac Address Table ------------------------------------------- Vlan Mac Address Type Ports ---- ----------- -------- ----- 103 0004.a3b9.67f0 DYNAMIC Twe1/0/45 103 0004.f2f2.3a6c DYNAMIC Twe1/0/45 103 0004.f2f7.ca1e DYNAMIC Twe1/0/45 103 001b.d432.e7c9 DYNAMIC Twe1/0/45

Re: VXLAN and RSPAN between branches

M02@rt37 — Wed, 14 May 2025 09:17:33 GMT

Thanks for that output @dijix1990

As discussed, RSPAN is not VxLAN-aware. So it causes MAC learning of mirrored (spoofed) trafic, which leads to flapping.

So, use ERSPAN, which avoids flooding and MAC learning issues beacuse it encapsulates mirrored trafic in GRE/IP, as @Torbjørn proposed.

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 10:02:05 GMT

How can I implement? my cisco 2960 can't erspan

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 10:04:34 GMT

I need to record sessions between two phones which placed on the same switch

Re: VXLAN and RSPAN between branches

Torbjørn — Wed, 14 May 2025 10:11:39 GMT

You could set up RSPAN on your 2960 and use the RSPAN VLAN as source VLAN for ERSPAN on your gateway device - that is assuming that the two phones are on the same site and your recording server is remote.

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 12:17:52 GMT

don't understand your idea.

OK, I have 2960 with monitor session

monitor session 1 source vlan 975 monitor session 1 destination remote vlan 103

what I need to do to encapsulate rspan to erspan on my asr1002-X

Re: VXLAN and RSPAN between branches

Torbjørn — Wed, 14 May 2025 11:17:44 GMT

On your ASR you configure VLAN 103 as source. Refer to the following config guide for detailed instructions: https://www.cisco.com/c/en/us/td/docs/routers/ios/config/17-x/lan-wan/b-lan-wan/m_lnsw-conf-erspan.html

Your source ERSPAN configuration would look something like this:

monitor session 100 type erspan-source source vlan 103

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 12:19:15 GMT

But asr1002x it's l3 device. It doesn't have l2 ports, there's only bdi for l2 features

Re: VXLAN and RSPAN between branches

Torbjørn — Wed, 14 May 2025 12:34:59 GMT

That is fine. You can use an L3 interface/subinterface as a source.

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 12:50:50 GMT

And how? Vlan 103 is l2 only how can I sent traffic of rspan via asr? I use erspan, but only for traffic L3 and I don't know how can I sent vlan 103 without gateway through erspan

Re: VXLAN and RSPAN between branches

dijix1990 — Wed, 14 May 2025 12:55:48 GMT

Maybe I can use l2tpv3 instead vxlan (xconnect)