How am I able to ping across trunk?

[hfakoor222]

Thought just occured to me as to whether or not I should be able to ping acorss this trunk ports

while doing this lab 

In doing a HSRP lab between the switches I recognized there needed to be communication between the switches to elect the active speaker and I realise now pings are going across the trunk port.

I have SVI vlan 11 and 21 set up on both D1 and D2 and pinging SVI 21 on D2 from D1

Can someone explain to me why this is allowed?

I have no L3 ports set up only trunk

so i assume it is because the vlans are going across the trunk port to get the ping across

If this is so what is the underlying protocol? It doesn't seem to me the pings are getting across via TCP. So how are they getting across?

using wireshark the vlans were indeed going across the trunks from D1 to D2.

[hfakoor222]

So i did a little research and this article says ICMP is second layer in the stack, and can even be sourced from NIC cards

"Any IP network device can send ICMP datagrams, including network interface cards and other devices that are commonly used in your environment."

https://www.pcwdld.com/what-is-icmp-and-port

So I think this clears some things up

[Jon Marshall · Accepted solution]

I may be misunderstanding your question but it is nothing to do with where ICMP sits in the TCP/IP stack. 

You have SVIs for both vlans on both switches and as long as those vlans are allowed on the trunk which they would be for HSRP setup then the SVIs will be up and so you can ping. 

Not sure what you mean by you have no L3 ports ? 

Jon

[MHM Cisco World]

right design need to NOT allow HSRP VLAN in trunk between two Distribute SW.

if you all HSRP VALN then Distribute not failover from active to standby if the link to Access SW/clients failed.