Layer 2 Etherchannel different carriers

[Louis Adams]

Hi,

I have 2 metro ethernet Layer 2 circuits by 2 different carriers.  They fully pass all vlan traffic.  When I do a show cdp neighbor command I see the switch on the other side.  My question is, is it possible to etherchannel 2 ports over different carries.  physically the 2 ports are not connected to each other just logically.

[Jaderson Pessoa]

No, if they are visible trough cdp / lldp is because they are directly connected. Some case are used "adpters or bridges" to improve more distance... But it is not the case :)

[Louis Adams]

They are not physically connected , each switch is connect physically to the carriers switch and then who knows how many other switches in between.  But the carriers switches pass all traffic, so it is logically like they are directly connected, if that makes sense.  so the problem I believe I would have is the switches would never be able to dell when one of the ports goes down because the actually physical port of the carrier switch most likely would be up, but one of the many other switches that could be in-between could be down.

Currently, I use one of them as a backup circuit.  But it's manual, when one of the carriers goes down I have to plug in the other carrier on both ends of the circuit.  Do you know if spanning tree would work in this case?  I am trying to find an auto solution were I don't have to manually bring up the backup circuit.

[Leo Laohoo]

Not going to work.
There's even a chance the ports at the ISP side will go into "error disable".

[balaji.bandi]

i do not believe this works. only you can do is Load-sharing the Load between carriers.

[Louis Adams]

right now one carrier is used as a backup, but when the other circuit goes down, I have to manually plug the backup circuit in, at both locations.  So I am trying to get it automated some way.  I thought etherchannel would be the only way.

[Joseph W. Doherty]

You've confirmed you cannot use any STP variant?

[Louis Adams]

No I have not tried that any variations, I am not all that familiar with the different stp variants.  One side I have a cisco 3850 stacked and the other side I have a 3750X stacked.  They are obviously layer 2 trunk ports.  What would you suggest to try? 

[Joseph W. Doherty]

Rapid-STP.

If STP is "allowed" by your MetroE vendors, you should be able to have both circuits hot. STP will block one, but if it fails, it will begin to use the other.

[Louis Adams]

Joseph thanks for reply.  Is there any way to know with out actually doing it if my vendors allow stp?  I know cdp traffic is allowed because when I do Show CDP neighbors it shows my switch on the other end of the circuit.

[Jaderson Pessoa · Accepted solution]

Well, you can use a track to get interface status and a EEM script to shutdown this interface and no shutdown in secondary link, for exemple;

In this case your primary link is: Ethernet 0/1
In this case your secondary link is: Ethernet 0/2

track 1 interface Ethernet0/1 line-protocol
delay down 5 up 5

event manager applet EnableSecondaryLink
event syslog pattern " %TRACK-6-STATE: 1 interface Et0/1 line-protocol Up -> Down"
action 1.0 cli command "enable"
action 1.1 cli command "configure terminal"
action 1.2 cli command "interface ethernet 0/2"
action 1.3 cli command "no shutdown"
action 1.4 syslog msg "Secondary Link activated"

event manager applet DisabledSecondaryLink
event syslog pattern " %TRACK-6-STATE: 1 interface Et0/1 line-protocol Down -> Up"
action 1.0 cli command "enable"
action 1.1 cli command "configure terminal"
action 1.2 cli command "interface ethernet 0/2"
action 1.3 cli command "shutdown"
action 1.4 syslog msg "Secondary Link Disabled"

You can tunning it using ip sla to monitor a next-hop to get a better information. This is a exemple to open your mind.

Regards,

[Louis Adams]

Jaderson,

Thanks very much for the info, I will for sure look into that.  Thanks for opening my Mind :)

[Jaderson Pessoa]

Great,

mark as solved and helpful.. it can will help other users to get this information easier

[Louis Adams]

Jaderson,

Just thought of something.  I think the problem I would have is if the circuit goes down not because of the directly connected switch, the line-protocol will not show down. thus will not trigger the event message.  Can I use an IP SLA to ping an address on the other side and then generate a syslog message off that?

[Louis Adams]

I found out how to use the ip sla to generate the syslog and there for I am working on EEM script do what you suggested.  I will update when done, but I think it will work.