Local Policy Routing for Local Router traffic to "RE-ENTER" the router

[XIE YAO]

Hi everyone,

I have seem below configuration from a CCIE RS note but couldn't figure it out, can somebody help to explain a bit?

CONFIG-SET: Local Policy Routing for Local Router traffic to "RE-ENTER" the router

+-----------------------------------------------------

| ip access-list extended LOCAL_TRAFFIC

| permit tcp any any eq 23                                                    - Match locally generated telnet traffic                                                   

| !

| route-map LOCAL_POLICY 10

| match ip address LOCAL_TRAFFIC                                     - Redirect local telnet traffic via the loopback interface

| set interface Loopback0                                                       - Traffic sent to loopback interface re-enters the router

| !

| interface Loopback0

| ip address 150.1.6.6 255.255.255.50

| !

| ip local policy route-map LOCAL_POLICY                             - Apply the policy for router generated traffic

If I understand correctly, set interface will set the output interface(for outgoing telnet traffic in this case), then what's the effect of setting a loopback interface to output this traffic, I mean there is nothing connecting back to the loopback interface, right?

TIA.

Regards

Yao

[cadet alain · Accepted solution]

Hi,

Let's suppose you have an outbound ACL or  a reflexive ACL or CBAC, none of these will take care of traffic generated by the router so you can use this trick,this way the traffic will be considered as transit traffic and it will be taken care of by the previous technologies.

Regards.

Alain

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[XIE YAO]

Thanks a lot, Alain.