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EIGRP routing over new L3 connections

we have our network separated into a northend and southend.  each data center has two 4510R+E switches running VSS between them.  we have both data center's connected with a port channel that connects to a 3750E switch.  we would like to remove the port channel and connect both data center's using EIGRP.  I have setup the ports as L3 with IP addresses, i have setup the EIGRP process with the network, I can ping the interface of the switch on my side of the network.  when i try to ping the other side, the ping fails.

What I am needing to happen, is to be able to drop the port-channel and then load balance over the L3 connections.

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1 ACCEPTED SOLUTION

Accepted Solutions
Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

If that is the other switch pair then that is your problem.

If you have "mac-address use-virtual" then the domain ID is used to generate the unique mac addresses per VSS pair.

Because you have the same domain ID on both VSS pairs they are generating the same mac addresses and that explains your arp table output.

There are a number of workarounds but i think changing the domain ID for one VSS pair would be the preferred solution because using the same domain ID affects other things such as port channels which you may want to use.

See this link for full details of possible solutions -

http://www.labminutes.com/blog/2012/12/cisco-6500-vss-domain-id-and-virtual-mac-address

Jon

27 REPLIES
VIP Super Bronze

EIGRP routing over new L3 connections

Not sure why ping fails between the 2 VSS sets.  The easier design would be to have a Layer-3 portchannel between the 2 sets with one /30 instead of 4.

HTH

New Member

EIGRP routing over new L3 connections

we were running the 4 connections for redundancy between the switches.  We have two sets of fibers, one is buried and the other is on the pole.  we wanted to make sure if one gets cuts there will have the other side to fall back on.

I am looking at building the port channels in our lab to see if that will work as well.

Hall of Fame Super Blue

EIGRP routing over new L3 connections

Your EIGRP adjancencies are not working properly ie. the RTO is 5000 and your Q cnt is > 0.

Do you see any messages in your log files regarding EIGRP ?

Are you sure you have connected the links correctly ie the addresses on either of the link are correct from your diagram but have you actually connected them up that way.

Jon

New Member

EIGRP routing over new L3 connections

I ran show cdp neighbor and verified that all the connections were going to the correct interfaces with the correct IP addresses.

Hall of Fame Super Blue

EIGRP routing over new L3 connections

If CDP is working then you have basic connectivity at L2 but you say you cannot ping the remote ends. This sounds more like a basic connectivity issue than an EIGRP problem.

Ping is obviously L3. Are you absolutely sure the IPs and subnet masks are correct ?

Jon

New Member

EIGRP routing over new L3 connections

show cdp neighbor

Device ID           Local Intrfce     Holdtme     Capability    Platform    Port ID

Northend              Ten 1/1/4         133             R S I  WS-C4510R Ten 1/1/1

Northend              Ten 2/6/1         172             R S I  WS-C4510R Ten 1/5/1

Northend              Ten 2/1/4         123             R S I  WS-C4510R Ten 2/1/2

Northend Interfaces

interface TenGigabitEthernet1/5/1

no switchport

ip address 10.254.250.1 255.255.255.252

end

!

interface TenGigabitEthernet2/5/1

no switchport

ip address 10.254.250.5 255.255.255.252

shutdown

end

!

interface TenGigabitEthernet1/1/1

no switchport

ip address 10.254.250.9 255.255.255.252

end

interface TenGigabitEthernet2/1/2

no switchport

ip address 10.254.250.13 255.255.255.252

end

Southend Interfaces

interface TenGigabitEthernet2/6/1

no switchport

ip address 10.254.250.2 255.255.255.252

end

interface TenGigabitEthernet1/1/4

no switchport

ip address 10.254.250.10 255.255.255.252

end

interface TenGigabitEthernet2/1/4

no switchport

ip address 10.254.250.14 255.255.255.252

end

Hall of Fame Super Blue

EIGRP routing over new L3 connections

Your 4500s are running VSS. Do you have different domain IDs for each pair ?

Jon

New Member

EIGRP routing over new L3 connections

Yes both pairs of 4500's are running VSS and each pair is running a different VTP domain

Hall of Fame Super Blue

EIGRP routing over new L3 connections

Not the VTP domain, the domain ID when you configure VSS.

Jon

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

To see the domain ID on your switches -

"sh switch virtual"

Jon

New Member

EIGRP routing over new L3 connections

#sh swi vir

Executing the command on VSS member switch role = VSS Active, id = 1

Switch mode                  : Virtual Switch

Virtual switch domain number : 1

Local switch number          : 1

Local switch operational role: Virtual Switch Active

Peer switch number           : 2

Peer switch operational role : Virtual Switch Standby

Executing the command on VSS member switch role = VSS Standby, id = 2

Switch mode                  : Virtual Switch

Virtual switch domain number : 1

Local switch number          : 2

Local switch operational role: Virtual Switch Standby

Peer switch number           : 1

Peer switch operational role : Virtual Switch Active

New Member

EIGRP routing over new L3 connections

from within the northend and southend switches i can ping the other side of the L2 interfaces.

Its when i am on another switch that is connected to either the northend or southend that i am unable to ping the other side the interface.

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

In addition to previous post, when you try to ping the remote end of the connection what does the arp table show ?

Jon

New Member

EIGRP routing over new L3 connections

Northend#sh arp | in 10.254.250

Internet  10.254.250.1            -   0008.e3ff.fc04  ARPA   TenGigabitEthernet1/5/1

Internet  10.254.250.2            0   Incomplete      ARPA  

Internet  10.254.250.9            -   0008.e3ff.fc04  ARPA   TenGigabitEthernet1/1/1

Internet  10.254.250.10           0   Incomplete      ARPA  

Internet  10.254.250.13           -   0008.e3ff.fc04  ARPA   TenGigabitEthernet2/1/2

Internet  10.254.250.14           0   Incomplete      ARPA  

Southend#sh arp | in 10.254.250

Internet  10.254.250.1            0   Incomplete      ARPA  

Internet  10.254.250.2            -   0008.e3ff.fc04  ARPA   TenGigabitEthernet2/6/1

Internet  10.254.250.10           -   0008.e3ff.fc04  ARPA   TenGigabitEthernet1/1/4

Internet  10.254.250.13           0   Incomplete      ARPA  

Internet  10.254.250.14           -   0008.e3ff.fc04  ARPA   TenGigabitEthernet2/1/4

Hall of Fame Super Blue

EIGRP routing over new L3 connections

Your arp tables are showing the same mac address for different IPs.

Do you have the same domain ID on both VSS pairs and if so are you using this command -

"mac-address use-virtual"

Jon

New Member

EIGRP routing over new L3 connections

yes i am using this command

"mac-address use-virtual"

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

Okay, you have posted the output of "sh switch virtual" from one VSS pair. What about the other pair.

I simply need to know if you are using the same domain ID for both VSS pairs. I suspect you are because of the arp tables but i want to confirm before leading you off in the wrong direction.

So can you run that command on both pairs and see if the domain ID is the same.

Jon

New Member

EIGRP routing over new L3 connections

#show swit virt

Executing the command on VSS member switch role = VSS Active, id = 1

Switch mode                  : Virtual Switch

Virtual switch domain number : 1

Local switch number          : 1

Local switch operational role: Virtual Switch Active

Peer switch number           : 2

Peer switch operational role : Virtual Switch Standby

Executing the command on VSS member switch role = VSS Standby, id = 2

Switch mode                  : Virtual Switch

Virtual switch domain number : 1

Local switch number          : 2

Local switch operational role: Virtual Switch Standby

Peer switch number           : 1

Peer switch operational role : Virtual Switch Active

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

If that is the other switch pair then that is your problem.

If you have "mac-address use-virtual" then the domain ID is used to generate the unique mac addresses per VSS pair.

Because you have the same domain ID on both VSS pairs they are generating the same mac addresses and that explains your arp table output.

There are a number of workarounds but i think changing the domain ID for one VSS pair would be the preferred solution because using the same domain ID affects other things such as port channels which you may want to use.

See this link for full details of possible solutions -

http://www.labminutes.com/blog/2012/12/cisco-6500-vss-domain-id-and-virtual-mac-address

Jon

New Member

EIGRP routing over new L3 connections

then that explains why we have to use a 3750e switch to connect both VSS switch pairs to gain connectivity between our northend and southend over our current port-channel.

Hall of Fame Super Blue

EIGRP routing over new L3 connections

I think it explains it yes. If the port channels connecting the VSS pairs to the 3750 were L2 then i suspect it would work. The docs are not entirely clear but it looks like for L2 MECs the actual mac address of a member link is used so the 3750 would not see duplicate mac addresses on different ports.

If the port channels had been L3 though then they use a mac address from the shared pool and so the 3750 would have seen the same mac on different ports and i don't think it would have worked.

Jon

New Member

EIGRP routing over new L3 connections

Could this be the other reason why EIGRP is having issues as well? with the Mac addresses being the same?

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

That is very probably is the reason. You do not have L3 connectivity working properly. I suspect once you change the domain ID (or whatever solution you choose) EIGRP will work properly.

Jon

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

Just to clarify.

On each VSS pair "sh ip eigrp neighbor" shows a Q cnt of 1. This means each side is waiting for an acknowledgement from the other. Acknowledgements are sent as unicast but because of the wrong arp tables i don't believe these acks are getting to the remote end.

Once you have L3 connectivity between the VSS pairs working properly then EIGRP should also start working.

Jon

New Member

EIGRP routing over new L3 connections

the document was very helpful.  We will probably just change the virutal domain ID and reboot the switches. 

Hall of Fame Super Blue

Re: EIGRP routing over new L3 connections

the document was very helpful.  We will probably just change the virutal domain ID and reboot the switches.

That's probably the best solution as it will allow you to run L3 port channels as interconnects if you decide that is the way you want to go.

Jon

New Member

EIGRP routing over new L3 connections

The documentation worked.  i was able to change the switch domain and reload the VSS switches.

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