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RT-AC87R - Help Identifying Interfaces for SNMP

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thatbeerguy

New Around Here
Hi all,

I'm running Asuswrt-Merlin 376.48. I enabled SNMP and am using Cacti to monitor my router. I've having trouble identifying what each interface is. I've attached a screenshot from Cacti. A couple of things I noticed:

- br0 and vlan2 seem to be mirror images of each other, same for eth0 and eth1.
- The spikes on the right side of eth0 and eth1 correspond to streaming video on my iPad on the 2.4G channel.
- I also streamed some 1080p video from my NAS to my HTPC on the 5GHz band but I saw nothing in Cacti that corresponded to that traffic.

So what exactly are these interfaces? Which is the WAN, which is the wifi, which is the ethernet LAN?

Thanks in advance!
 

Attachments

  • Cacti.jpg
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eth0 is the WAN port.
eth1 is the 2.4 GHz interface
wifi0 is the 5 GHz interface (on the other router models it's eth2)
br0 is the LAN bridge, bridging LAN, eth1 and eth2/wifi0

VLAN2 is usually Internet traffic I believe (I've never dug too deep in the vlan stuff, especially since it can sometime change between versions).
 
eth0 is the WAN port.
eth1 is the 2.4 GHz interface
wifi0 is the 5 GHz interface (on the other router models it's eth2)
br0 is the LAN bridge, bridging LAN, eth1 and eth2/wifi0

VLAN2 is usually Internet traffic I believe (I've never dug too deep in the vlan stuff, especially since it can sometime change between versions).

Thanks! I wonder why I'm not seeing a wifi0 interface.
 
Thanks! I wonder why I'm not seeing a wifi0 interface.

Possibly because Asus didn't expose it in their MIB definitions (the MIB I use were intended for the other router models, and only the RT-AC87U has that wifi0 interface).
 
eth0 is the WAN port.
eth1 is the 2.4 GHz interface
wifi0 is the 5 GHz interface (on the other router models it's eth2)
br0 is the LAN bridge, bridging LAN, eth1 and eth2/wifi0

VLAN2 is usually Internet traffic I believe (I've never dug too deep in the vlan stuff, especially since it can sometime change between versions).

I don't think the MIB is accurately labeling the interfaces.

I'm not sure about eth0 being the WAN port, at least as its getting reported. The traffic is too high on my net - I was guessing it was the wired ports, and eth1 being the wireless.

vlan1 seems to be the WAN traffic.

I have no clue what vlan2 is - the numbers being reported are so high it almost looks like all traffic in and out of all ports on the router, at least on my setup.
 
I don't think the MIB is accurately labeling the interfaces.

I'm not sure about eth0 being the WAN port, at least as its getting reported. The traffic is too high on my net - I was guessing it was the wired ports, and eth1 being the wireless.

vlan1 seems to be the WAN traffic.

I have no clue what vlan2 is - the numbers being reported are so high it almost looks like all traffic in and out of all ports on the router, at least on my setup.

eth0 is definitely the physical WAN port on your router. Traffic can be higher if you use, for example, PPPoE, as it would carry also the overhead of PPP packets.

You can ssh into your router to manually check the packet count on each interfaces to see if they would be mislabeled in the MIB.
 
Another interesting thing I found. When I ssh into my router and do an ifconfig, vlan2 has my WAN IP.

Yes, that interface is internally known by the firmware as being the "INTERNET" interface. That might be to provide something constant regardless of whether your Internet interface is Ethernet, PPP or USB based.

Code:
admin@Stargate87:/tmp/home/root# nvram get wan0_ifname
vlan2
 
My thinking is there is a disconnect between the router firmware labeling of interfaces, and what the SNMP MIB defines them as. Internally, I'm pretty sure that eth0 is the WAN port, and vlan2 also encompasses external internet traffic. But looking at the send/recv counts from SNMP for eth0 and vlan2, I don't think that is the interfaces they are reporting on, they both look way too high.
 
You can try comparing with kernel-level info:

Code:
cat /proc/net/dev
 
You can try comparing with kernel-level info:

Code:
cat /proc/net/dev

vlan1 from proc/net/dev is vastly larger than the vlan1 being reported by SNMP. I'm pretty sure the vlan1 from SNMP is actually the WAN traffic - it seems to match with the sum of traffic monitor's per IP device traffic for any given time period.
 

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