4500-E vss MEC

[serge123]

Hi all,

I was reading today that Cisco Release IOS XE 3.4.0SG does not support Layer 3 MEC on the 4500 platform.

I would like to configure my MEC and run OSPF on my UPLINK.  I would also like to prioritise 1 uplink over the other.

Would something like this work or can someone recommend a better solution not too sure abut the ospf cost.

thank you

SWITCH-VSS(config)#interface Port-channel 10

SWITCH-VSS(config-if)#switchport          

SWITCH-VSS(config-if)#switchport mode trunk

SWITCH-VSS(config-if)#switchport nonegotiate

SWITCH-VSS(config-if)#switchport trunk allowed vlan 100

SWITCH-VSS(config)#interface range gigabitEthernet 1/2/48, gigabitEthernet 2/2/48

SWITCH-VSS(config-if-range)#switchport

SWITCH-VSS(config-if-range)#switchport mode trunk

SWITCH-VSS(config-if-range)#switchport nonegotiate  

SWITCH-VSS(config-if-range)#switchport trunk allowed vlan 100

SWITCH-VSS(config-if-range)#channel-group 10 mode desirable

SWITCH-VSS(config)#interface port-channel 15

SWITCH-VSS(config-if)#switchport

SWITCH-VSS(config-if)#switchport mode trunk

SWITCH-VSS(config-if)#switchport nonegotiate

SWITCH-VSS(config-if)#switchport trunk allowed vlan 105

SWITCH-VSS(config-if)#interface range gigabitEthernet 1/3/48, gigabitEthernet 2/3/48

SWITCH-VSS(config-if-range)#switchport mode trunk

SWITCH-VSS(config-if-range)#switchport nonegotiate

SWITCH-VSS(config-if-range)#switchport trunk allowed vlan 105

SWITCH-VSS(config-if-range)#channel-group 15 mode desirable

SWITCH-VSS(config)#interface vlan 100

SWITCH-VSS(config-if)#ip address 10.0.0.1 255.255.255.252

SWITCH-VSS(config-if)#int vlan 105

SWITCH-VSS(config-if)#ip address 10.0.0.5 255.255.255.252

SWITCH-VSS#conf t

Enter configuration commands, one per line. End with CNTL/Z.

SWITCH-VSS(config)#router ospf 100

SWITCH-VSS(config-router)#router-id 10.10.10.10

SWITCH-VSS(config-router)#log-adjacency-changes

SWITCH-VSS(config-router)#nsf

SWITCH-VSS(config-router)auto-cost reference-bandwidth 1000

SWITCH-VSS(config-router)#network 10.0.0.0 0.0.0.3 area 0

SWITCH-VSS(config-router)#network 10.0.0.4 0.0.0.3 area 0

SWITCH-VSS(config-router)#passive-interface default

SWITCH-VSS(config-router)#no passive-interface port-channel 10

SWITCH-VSS(config-router)#no passive-interface port-channel 15

SWITCH-VSS(config-router)#no passive-interface vlan 100

SWITCH-VSS(config-router)#no passive-interface vlan 105

SWITCH-VSS(config-router)#^Z

SWITCH-VSS(config)#int vlan 100

SWITCH-VSS(config-if)#ip ospf cost 10

SWITCH-VSS(config-if)#int vlan 105

SWITCH-VSS(config-if)#ip ospf cost 100

SWITCH-VSS(config-if)#

[Reza Sharifi]

Hi,

I am not sure if OSPF priorities will work that way since you assigned them to vlan interfaces instead of the portchannel interfaces

What device are you connecting the VSS pair to?

HTH

[serge123]

Cisco 3550

[Jon Marshall]

Serge

As Reza says it would be useful to know what devices are connected to the 4500 via these two etherchannels.

I believe you can use OSPF cost on the SVIs so it may well work but some more information would be helpful. I should also say i am talking in general about using cost on an SVI and Reza has far more experience with VSS than i do so i may well be wrong.

Jon

[serge123]

Cisco 3550,  I'm not sure of the IOS unfortunatly I don't have access to them and they are asking for ospf.

OSPF will be running in the 3550 facing my VSS switch and BGP on the wan side.

I will be running EIGRP on my LAN and OSPF to the 3550.

[Jon Marshall]

So you are having two etherchannels to the same device ?

I'm just not sure why you are using two etherchannels as one should give you the redundancy ie. if one of the 4500s goes down you still have the connection from the 3550 to the other 4500.

Again though, like i say it could be due to may lack of knowledge in terms of VSS.

Hopefully Reza can add to this.

Jon

[serge123]

2 X 3550  that goes into the MPLS cloud

[Jon Marshall]

That makes more sense.

I think applying cost to the SVI should work but the obvious problem is that if one link in the active MEC fails because the cost is applied to the SVI it will probably still favour that remaining link.

That would only be applicable if the actual link went down though ie. if the switch crashed then the other MEC only has one link available anyway.

Jon

[Reza Sharifi]

I have never tested VSS with priority on the SVI. I have only done it with layer-3 MEC with IP address on the Etherchannle. If the priority does not work for you, you can simply let OSPF do equal cost load balancing. You also need a layer-3 link between the 3550s.

HTH

[serge123]

ok thanks, I will try it next week