Any suggestion on how to replaced 3560 by an ASR1001 with no downtime?

[carensantos23]

We will be replacing our 3560 with ASR1001. 3560 is connected to a 2960 switch which facing the Uplink. 3560 is running eBGP peer with only 2 neighbor. My plan is to copy the major configuration of 3560 and paste to the ASR1001 and connect on that same 2960 switch. Would this be fine? Any suggestion will be highly appreciated.

Configuration is attached:

Thanks.

[SANTHOSHKUMAR SARAVANAN]

Hi , 

Connect your ASR1001 on your Network (towards 2960) 

1) configure HSRP for your LAN Segment ( Between 3560 & ASR1001) , at this moment your 3560 should be Active for HSRP Group . All traffic should come to 3560 for exiting your campus

2) Move one BGP Negibhors towards ASR1001 , ensure stability of link .  

3) Then make ASR 1001 as active for HSRP Group , so traffic will go via ASR 1001

4) Move the Second BGP neigbhor from Switch to ASR 1001

5) Finally you can remove 3560 from your network . 

HTH

Sandy

[carensantos23]

3560 Configuration:

!

!
interface Vlan 3333
 description ISP Link 1
 ip address 11.11.11.9 255.255.255.252
!
interface Vlan7777
 description  ISP Link 2
 ip address 22.22.22.21 255.255.255.252
!

!

router bgp 54321

 bgp router-id 1.2.3.4

 bgp log-neighbor-changes

 network 1.2.3.0 mask 255.255.248.0

 neighbor 11.11.11.10 remote-as 55555

 neighbor 11.11.11.10 transport path-mtu-discovery

 neighbor 11.11.11.10 password 7 1231415151B1E5429203557

 neighbor 11.11.11.10 update-source Vlan3333

 neighbor 11.11.11.10 soft-reconfiguration inbound

 neighbor 22.22.22.22 remote-as 44444

 neighbor 22.22.22.22 transport path-mtu-discovery

 neighbor 22.22.22.22 update-source Vlan7777

 neighbor 22.22.22.22 soft-reconfiguration inbound

  no auto-summary

!

ASR Configuration:

router bgp 54321

 bgp router-id 1.2.3.5

 bgp log-neighbor-changes

 network 1.2.3.0 mask 255.255.248.0

 neighbor 11.11.11.10 remote-as 55555

 neighbor 11.11.11.10 transport path-mtu-discovery

 neighbor 11.11.11.10 password 7 1231415151B1E5429203557

 neighbor 11.11.11.10 update-source g0/0/0.3333

 neighbor 11.11.11.10 soft-reconfiguration inbound

 neighbor 22.22.22.22 remote-as 44444

 neighbor 22.22.22.22 transport path-mtu-discovery

 neighbor 22.22.22.22 update-source g0/0/0.7777

 neighbor 22.22.22.22 soft-reconfiguration inbound

 no auto-summary

Is my update source syntax command from 3560 to ASR correct?

Thanks...

[SANTHOSHKUMAR SARAVANAN]

Hi 

 I think presently on your switch 3560 , you have created SVI for your WAN Link .So you used update source as your VLAN number .

On your ASR router , you can directly terminate on L3 Interface . Like interface Gi0/0/0 for WAN Link 1 and Gi/0/0/2 for WAN Link 2

on this case 

neighbor 11.11.11.11 update-source g0/0/0

 neighbor 22.22.22.22 update-source g0/0/1

HTH

Sandy

[carensantos23]

Would there be a conflict if I will just configure the BGP on the ASR and connect to 2960 without doing any HSRP? I mean, would it be possible for them to work independently?

Thanks Sandy for reponding...:)
 

[SANTHOSHKUMAR SARAVANAN · Accepted solution]

Hi Caren , 

             By this way  , you cant move your LAN traffic towards to ASR1001 . Only you can move your WAN Link which of no use for you . 

          I can suggest you one way over here , configure your LAN interface on your ASR1001 .Keep it shutdown until you establish your 1st link . Once you establish your WAN Link .

Shut your LAN interface on 3560 switch 1st , then un shutdown your router LAN interface (else you have IP address duplication , your LAN segment will loose network connectivity . )

During this duration , your LAN segment may experience some packet drop reaching out of your campus , 

Once you done your movement with first link , then swap your Second WAN link towards ASR1001

By this way some Sensitive application will have time out , need re connection  .

When you use HSRP you will have 4 packet drop during fallback which is invisible to end user

HTH

Sandy 

[carensantos23]

I forgot to mention that this 3560 switch only serve as gateway to the internet and do some QoS shaping to other branches. Basically, only 2 ports of 3560 is active and connected to the switch. All connections are in 2960 including a switch for few LAN users and another router which do QoS to another branch as well.

From this setup, can I expect no issues with BGP which will run on both ASR and 3560?

Thanks again Sandy :)

[SANTHOSHKUMAR SARAVANAN]

Share me your switch config . I can assist you better .

HTH
Sandy

[carensantos23]

Attached is the configuration:)

Thanks for your help...