Hi All, Regarding the question "Maybe before step2 there will be needed apic2 "Decommission". Not sure" It's a yes, I needed to do decommission in order to successfully replace APIC. Here are my notes from the action: https://howdoesinternetwork.com/2019/aci-multipod-enable-standby-apic Hope this helps.. cheers!!
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Hi Guys, There is a paragraph in Cisco ACI docs about per-IP EPG definition where I could map few VMs from one segments/BD to an EPG but I cannot find how to configure that in real life. I have a simple network based ACI deployment where each BD is mapped to one EPG which represents an legacy VLAN used in customer environment before migration. We now need to implement some ACLs (contracts) to define inbound and inter VLAN communication filters so I suppose I would need to map source VMs to one additional EPG and destination VMs in one additional EPG so that I can define app profile with contract and filters to allow or deny the communication between them. I know and I did configure VLAN-to-EPG mappings and that part works well, this more granular next step is not clear to me on how should be configured...? thanks... valter
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I wrote about how to do this in the past. You should find your answer in my post:
Unidirectional communication filter between two VLANs: http://howdoesinternetwork.com/2012/allow-vlan-access-but-no-back
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Actually there is a simple solution. I needed a lot of time to get to this so it's worth sharing. There is a special type of Access list called reflexive. This kind of access list will allow traffic from one VLAN to another only if the communication is established in other direction before that. It can't be used for IP traffic but only for every protocol separatelly so you will need to use more rows in ACL to allow TCp, ICPM etc, but it will solve your problem. Here is how is done: Let's say that you have two VLANs: VLAN 10 and VLAN 20. VLAN 10 INTERFACE = 10.10.10.1 /24 VLAN 20 INTERFACE = 10.10.20.1 /24 VLAN 10 can access VLAN 20 but, VLAN 20 can't access VLAN 10. (That was the whole problem, to allow access only in one direction). To be able to do so, you need to let the traffic from VLAN 10 go to VLAn 20 but you need also to let this communication to go back to VLAn 10 in order to close the communication bidirectional functionality. Almost every communication needs to get back to source in order to make the circle functional. But, if you allow this communicaton to go back to VLAN 10, you will alow all the communication in both ways, and this is the problem that we can solve using reflexise ACLs. We will make extended named ACL with name EASYONE: ip access-list extended EASYONE permit tcp 10.10.20.0 0.0.0.255 10.10.10.0 0.0.0.255 established (The work established at end of this ACL row means that this TCP traffic from VLAN 20 to VLAN 10 will only be allowed when it's from some communication that was started from VLAN 10, a going back traffic) permit icmp 10.10.20.0 0.0.0.255 10.10.10.0 0.0.0.255 echo-reply (This echo-reply row will allow VLAN 20 to reply to ping and other ICMP requests) deny ip 10.10.20.0 0.0.0.255 10.10.10.0 0.0.0.255 permit ip any any (This row will deny all other traffic from VLAN 20 directed to VLAN 10 but with permit ip any any it will allow VLAN 20 to go let say to gatway and further to internet and other VLANs) Finally, we will put the ACL EASYONE to VLAN 20 L3 interface interface vlan 20 ip access-group EASYONE in To conclude the config without comments, indeed easy now when is done: ip access-list extended EASYONE permit tcp 10.10.20.0 0.0.0.255 10.10.10.0 0.0.0.255 established permit icmp 10.10.20.0 0.0.0.255 10.10.10.0 0.0.0.255 echo-reply deny ip 10.10.20.0 0.0.0.255 10.10.10.0 0.0.0.255 permit ip any any exit interface vlan 20 ip access-group EASYONE in The credit for the solution goes to my mentor and friend Sandra who did the configuration and lab for it but more than that she came out with the established word at end of the ACL and whole reflexive ACL solution. For this detailed article and more about Cisco, Juniper, etc configurations from real life please visit blog howdoesinternetwork.com and enjoy networking as we do.
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