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Trusted Contributor
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Registered: ‎06-11-2009
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Q in Q - customer ports as trunks?

Most of the documentation I have read about q in q says that access ports are considered to be part of the customer VLANS. I have a situation where I don't have any access ports, they are all trunks, but would like to use q in q since I will have overlapping VLAN ranges... So is it possible to have C-VLANS configured using trunks ports?
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Re: Q in Q - customer ports as trunks?

if memory serves, with QinQ on the EX platform, you actually still configure the port as an Access port in the S-VLAN even though you will be receiving tagged frames.  I know that threw me off when I was trying to learn it and test it, but if you think about it it kind of makes sense, because in a QinQ environment the switch is just adding / removing the S-VLAN tag when traffic enters / exits the switch toward the customer, and doesn't care what the C-VLAN tag is

 

will

 

 

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Re: Q in Q - customer ports as trunks?

So just to confirm... is this the process?

 

 

 

 

start---Customer(VLAN500)-----C-VLAN(VLAN4001)----S-VLAN(4001)------SVLAN(4001)-----Customer(VLAN500)-----Finish

 

So I have a customer comming in using vlan 500, it hits the first q-in-q point where VLAN4001 is assigned.

VLAN4001 then traverses through a few service provider hops, all using VLAN4001, then goes out the last C-VLAN port where 4001 is removed and the original tag is used.

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Re: Q in Q - customer ports as trunks?

I believe that should be the case, yes.

 

were you able to test this for your situation?  did this solve your problem?

 

will

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Re: Q in Q - customer ports as trunks?

Yes i was able to set this up successfully in a lab enviornment... it worked quite well actually

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Re: Q in Q - customer ports as trunks?

one thing to caution you on -- make sure you raise the interface MTU of the QinQ 'core' interfaces to at least 1522 (though I would recommend higher just to be able to allow larger frames in the future).  I believe 1522 would be the minimum because Juniper's MTU calculation includes the L2 info (unlike Cisco I believe) -- 1500 byte payload + 14 byte MAC info + 4 byte C-VLAN Tag + 4 byte S-VLAN tag

 

if you do not, with simple tests like pings etc will flow fine, but 'normal' traffic that has higher frame sizes will not work properly

 

you can see this behavior by sending a larger ping with the DF bit set in your tests.  You want to make sure at a minimum a full-sized 1500 byte payload will go through.  at a minimum you would want to be able to send a ping with size 1472 with the DF bit set through the QinQ network from customer switch to customer switch (1472 + 8 byte ICMP header + 20 byte IP header = 1500 byte payload)

 

will

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Re: Q in Q - customer ports as trunks?

[ Edited ]

Can i configure a customer port (access port) to be a member of multiple QinQ VLANs?

I would like to be able to have some customer VLANs in one tag and others with anothe tag.  So somthing like this:

 

{master:0}[edit interfaces ge-0/0/26 unit 0 family ethernet-switching]
root# show
port-mode access;
vlan {
members [ s-vlan1 s-vlan2 ];
} 

root# run show configuration vlans
}
s-vlan1 {
vlan-id 4001;
dot1q-tunneling {
customer-vlans 500-600;
}
}
s-vlan2 {
vlan-id 4002;
dot1q-tunneling {
customer-vlans 10;

 

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Registered: ‎11-02-2010
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Re: Q in Q - customer ports as trunks?

So you want to deliver two different circuits? Are they going to two different destinations?

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Re: Q in Q - customer ports as trunks?

They will be going to the same destination, but for other reaons I'd like to have them as seperate tags

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Re: Q in Q - customer ports as trunks?

[ Edited ]

I have never tried it, but I guess it might work.

 

We typically use 1 port per circuit, and if a customer requests qinq we do the whole vlan range 1-4096 so that way they do not have to contact us to coordinate for new transit vlans.

 

Are you wanting to do different rate-limits or QoS classifications for each circuit?

 

In 10.3 documentation it states:

 

"An interface can be a member of multiple S-VLANs. You can map one C-VLAN to one S-VLAN (1:1) or multiple C-VLANs to one S-VLAN (N:1). Packets are double-tagged for an additional layer of segregating or bundling of C-VLANs. C-VLAN and S-VLAN tags are unique; so you can have both a C-VLAN 101 and an S-VLAN 101, for example."

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Re: Q in Q - customer ports as trunks?

Just thinking about it and I may not need it after all.... I think I single s-vlan mapping all vlans would work. One other thing, can traffic flow between two c-vlans if they have the same tag? Similar to normal traffic in a normal vlan.... So what would happen if I had two servers which needed to talk to each other and they were both configured as access ports in the same QinQ vlan? Would the communication work? Also? The s-vlan is where the new tag is first added to the Ethernet frame right? Thanks
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Re: Q in Q - customer ports as trunks?

Yes it should work.

 

But remember, if this is an actual service provider deployment, you wouldn't be talking spanning-tree with a customer so the potential for a loop exsists.

 

I rarely deliver two of the same circuit to one customer site to prevent loops.

 

 

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Re: Q in Q - customer ports as trunks?

I'll explain the reason for needing this a bit more....  I look after a public cloud providor, when we get a customer they are assgined a VLAN.  We are starting to run out of VLANs so we need a way to be able to duplicate our VLAN numbers as traffic flows through our core network....  QinQ is the answer.

 

Since we are totally virtualized the switchports which connect to our virtual servers have a number of VLANs trunked into them, some are for customers and some are for internal use which is why i was curious about assigning multuple S-VLANs to the access ports.

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Re: Q in Q - customer ports as trunks?

Ah, good application for qinq.