why we cannot use the IP address of the Layer 3 interface vlan for NAT or PAT in cisco ace 4710 ??

[Saroj Pariyar]

why we cannot use the IP address of the Layer 3 interface vlan for NAT or PAT in cisco ace 4710 ??

[Jorge Bejarano]

Saroj,

Could you elaborate a little bit more your question?

Could you paste the configuration related and explain what error you are getting or what you are trying to accomplish?

Jorge

[Cesar Roque]

Hi Saroj,

If you try that the ACE will show an error like this:

interface vlan 144

  ip address 10.198.44.16 255.255.255.0

  alias 10.198.44.174 255.255.255.0

  peer ip address 10.198.44.15 255.255.255.0

  access-group input ALLOW

  access-group output ALLOW

  nat-pool 1 10.198.44.201 10.198.44.201 netmask 255.255.255.0 pat

  service-policy input MGMT

  service-policy input TT

  no shutdown

ACE-4710H/Admin# conf t

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

ACE-4710H/Admin(config)# interface vlan 144

ACE-4710H/Admin(config-if)# nat-pool 2 10.198.44.16 netmask 255.255.255.0 pat

Error: Specified ip address duplicates with an existing ip address configured in

the context

You can use a VIP address for  nat-pool otherwise you need to use an available IP address for a nat-pool. 

---------------------
Cesar R
ANS Team

[vpurbiya]

Hi saroj

The reason why you get the error is Ace allocates MAC address to interface and Nat and VIP ip from different pools
Generally interface mac is from a BIA pool unless you are sharing interface between contexts.
And NAT/ VIP gets a MAC address from virtual mac pool.
This classification is done to identify traffic forwarding from ace perspective in case you have context based setup
So that is why it doesn't let you assign Nat. Ip same as interface ip as it needs to allocate a mac from virtual mac pool

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