Routing

Hello,

I have some confusions when i try to understand vlan tag in the interfaces and in the VPLS routing instance.

Topology of lab:

Customer_switch1 <--trunk--> MX_PE1 <----> (core) <---> MX_PE2 <--trunk--> Dell-Switch <-(qinq)-----(trunk)--> customer_switch2.

Configuration:

MX_PE1:

interfaces ae19 {
description TEST-VPLS;
encapsulation ethernet-vpls;
unit 0 {
input-vlan-map {
push;
vlan-id 20;
}
output-vlan-map pop;
family vpls;
}
}

routing-instances VPLS-TEST {
instance-type vpls;
interface ae19.0;
vrf-target target:123:123;
protocols {
vpls {
site-range 100;
no-tunnel-services;
site site1 {
site-identifier 1;
interface ae19.0;
}
}
}

}

MX_PE2:

interfaces ae18.20 { 
description VPLS-TEST;
encapsulation vlan-vpls;
vlan-id 20;
family vpls;

}

routing-instances VPLS-TEST {
instance-type vpls;
interface ae18.20;
vrf-target target:123:123;
protocols {
vpls {
site-range 100;
no-tunnel-services;
site site2 {
site-identifier 2;
interface ae18.20;
}
}
}

}

It work perfectly ! Each interface vlan on Customer_switch1 can ping corresponding interface vlan on Customer_switch2.

Because i dont include vlan-id statement in routing-instances VPLS-TEST so the default behavior is vlan-id none. Therefore the packets will be transferred between two sites in core network without vlan tags (im not sure about this).

So somethings are excess in my configure !

On PE1, the interface ae19 push vlan 20 to the packets (double vlan tags). Otherwise, the vpls routing-instance pops all vlan tags of the packets before transfer them to the remote PE.

So i wonder that i just need to make the vlans between interface of each site match when the packets go in and go out the intefaces when i configure a vpls with multi vlans. Dont need to include vlan-id statement in routing-instances because i dont see any benefits ?

Thanks for any answer !

Hello,

Actually if there is no vlan-id configured under the vpls the default behaviour is to send the packets with the vlans they come with, so not like vlan-id none.

The vlan-id configured under the routing-instance is to perform the vlan normalization you are configuring on the interface without so much configuration. For example, on PE1 you are pushing vlan 20 to the incoming packets, and taking the top vlan of the outgoing packets, do a "show interface ae19.0" you will see that operation is specified. If you remove the input/output vlan maps from ae19.0 and configure vlan-id 20 under the vpls routing-instance it should do the same (check the "show interface ae19.0" and the input/output push/pop operations should appear the same as before). So that would be the advantage of vland-id under vpls, it's an alternative to vlan-maps under the inteface.

Thanks for your answer,

You are right, i have checked. So when i configure input/out-vlan-map under interface, it work in the same way with include vlan-id under routing-instance (push vlan at input and pop at output) even though the input packets from physical interface have vlan tag or not. If i include the vlan-id statement under interfaces interface-name unit x, the behavior is the same if i configure input/out-vlan-map under interface, and the behavior is swap the vlan of the packets if i configure vlan-id under routing-instance.

Now i understand it carefully. Thanks again !