Configure Primary/Standby L2 ports on Catalyst C1000

[dima.ostapenko]

I need to configure 2 L2 ports on Catalyst C1000 with Primary/Standby functionality. These ports connected to 2 ISP with L2 links.

Primary port should be up and standby should be down until primary port will be down.

On 2960 switches we used flexlink for this case, but there is not this feature on C1000. 

I tried to configure REP with 2 edge no-neighbor ports (primary and preffered) but get error  "Error: Segment id 1023 already has one edge no-neighbor port. Cannot configure another edge no-neighbor port."

Any ideas How can I realise this scheme on Catalyst C1000?

Thanks.

[marce1000]

 -  Ref : https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst1000/software/releases/15_2_7_e/configuration_guides/lyr2/b_1527e_layer2_c1000_cg.pdf
                        >...REP has these limitations:
               • You must configure each segment port; an incorrect configuration might cause forwarding loops in the
networks.
               • REP can manage only a single failed port within the segment; multiple port failures within the REP
segment cause loss of network connectivity.
              • You should configure REP only in networks with redundancy. Configuring REP in a network without
redundancy causes loss of connectivity

 M.

[dima.ostapenko]

As I understand REP isn't helpfull in my case.

[Reza Sharifi]

According to this document, you need a Network Essentials license for REP.

Also, it is supported starting with Cisco IOS XE Fuji 16.9.1 

see link

https://www.cisco.com/c/en/us/td/docs/switches/lan/cisco_ie3X00/software/17_4/b_redundancy_17-4_iot_switch_cg/m_1610-layer2-rep-cg.html#:~:text=Resilient%20Ethernet%20Protocol%20(REP)%20is,failures%2C%20and%20improve%20convergence%20time.

The other option would be to use a PO is the provider supports it, if not you would have to use STP port priority.

HTH

[dima.ostapenko]

Both providers are different with no-cisco equipment. I can use only port status on my C1000 switch. Maybe it possible to use tcl script for it but I have not expirience with it and couldn't find if it is supported on C1000.

[Reza Sharifi]

And you are peering with both providers using layer-2 links and not layer-3?

HTH

[dima.ostapenko]

Yes, ports to both providers are trunks and allowed vlan the same on both links. But its a different outside networks and primary link has much better capabilities. So we need to up backup link only when primary  is down.

[balaji.bandi]

Yes, ports to both providers are trunks and allowed vlan the same on both links. But its a different outside networks and primary link has much better capabilities. So we need to up backup link only when primary  is down.

how is your network diagram looks like ? if this Layer 2 only, how is your routing take place.

can you provide config of Cat 2900 switch which was working ?

[dima.ostapenko]

interface GigabitEthernet1/0/43
switchport trunk allowed vlan 2020,2220
switchport mode trunk
switchport backup interface GigabitEthernet1/0/44
switchport backup interface GigabitEthernet1/0/44 preemption mode forced
!
interface GigabitEthernet1/0/44
switchport trunk allowed vlan 2020,2220
switchport mode trunk
!

Routing isn't use on this switch.

[balaji.bandi]

i see some limitation as i see also other posters mentioned here ?

where is this terminating ISPlink to Layer 2- Layer 2 switch to what device ?

that device (can be Firewall or router ) - can make decision based on the tracking ?

can you post the complete diagram to understand.

couple of option you can use EEM Script to see the links Physical one move to other side.

but i would take advantage where the Layer 3 configured.

[Max Jobs]

Since Catalyst C1000 switches do not support FlexLink or REP (Resilient Ethernet Protocol) directly, you can achieve similar functionality using a combination of features available on the switch. One approach is to use Interface Tracking in conjunction with HSRP (Hot Standby Router Protocol) or VRRP (Virtual Router Redundancy Protocol) for Primary/Standby functionality.

Here's a high-level overview of how you can configure it:

1. Configure Interface Tracking: Interface Tracking allows the switch to monitor the status of a primary interface and adjust the priority of the HSRP/VRRP group accordingly. When the primary interface goes down, the standby interface takes over.

   Example Configuration:

interface GigabitEthernet1/0/1
 description Primary ISP Connection
 ip address x.x.x.x y.y.y.y
 !
interface GigabitEthernet1/0/2
 description Standby ISP Connection
 ip address z.z.z.z a.a.a.a
 !
track 1 interface GigabitEthernet1/0/1 line-protocol​

• Configure HSRP or VRRP: Configure HSRP or VRRP on the interfaces connected to the ISP routers. Ensure that the priority is higher on the primary interface and lower on the standby interface.

  Example Configuration for HSRP:

interface GigabitEthernet1/0/1
 standby 1 ip x.x.x.x
 standby 1 priority 110
 standby 1 preempt
 !
interface GigabitEthernet1/0/2
 standby 1 ip x.x.x.x
 standby 1 priority 100
 standby 1 preempt

Replace x.x.x.x with the IP address of the HSRP/VRRP virtual gateway.

• Configure Default Gateway: Set the default gateway of your internal devices to the virtual IP address of the HSRP/VRRP group.

  Example:

ip route 0.0.0.0 0.0.0.0 x.x.x.x

Replace x.x.x.x with the IP address of the HSRP/VRRP virtual gateway.

With this configuration, the switch will actively monitor the primary interface (GigabitEthernet1/0/1) using interface tracking. If the primary interface goes down, the switch will decrement the priority of the HSRP/VRRP group associated with it, causing the standby interface (GigabitEthernet1/0/2) to take over. Once the primary interface is restored, the switch will raise the priority of the HSRP/VRRP group back to normal, making the primary interface active again.