What is my Switch IP? [closed]

Question

I struggle low network performance. When I copy a file to one server to another server, the network speed up to 8 Gb/s. I think that this issue can be missing switch configuration. How can I learn switch IP?

Answer 1

There is not really any common "trace" mechanism for Ethernet. (Some such mechanisms kind of exist, like 802.1ag OAM trace, but they're really rare in practice – and more importantly, they don't tell you the IP address anyway, they only tell you the MAC address, because that's what switches work with.)

What you can get is the address of the switch that's directly connected to you (i.e. the 1st L2 hop only). Most enterprise Ethernet switches support LLDP for that purpose – although it is not always enabled, and even when it's enabled not all switches actually include the "Management IP" field, but it's still the closest you can get.

On a Linux server, use lldpctl if lldpd installed; otherwise ladvdc if ladvd is installed; otherwise start a packet capture with tcpdump -e -v -n -i eth0 "ether proto 0x88cc" and wait a few minutes for the periodic LLDP broadcast to show up.

On a Windows server, you could run LDWin or do a packet capture either with pktmon (instructions) or Wireshark (the same ether proto 0x88cc capture filter).

Finally, keep in mind that not all Ethernet switches have IP addresses in the first place. IP is not part of the core functionality of a switch – it is for management and configuration only – and even in enterprise networks you can encounter fully unmanaged switches that do not offer any configuration.