Subject: Re: Re: RE: draft-lasserre-vkompella-ppvpn-vpls as working group draft

From: Du Wenhua <[email-masked]>
Date: Wed, 16 Apr 2003 06:12:20 +0800

Hi, Ali Sajassi

　　　　　　　　Du Wenhua
　　　　　　　　[email-masked]
　　　　　　　　　　2003-04-16

At 13:22:00 2003-04-15, Ali Sajassi wrote:
>>> >I think there is misunderstanding in here. P-VLAN is just to represent a
>> >VPLS-id inside the QinQ domain - e.g., VPLS-id can be a 32-bit id for MPLS
>> >domain and can be a 12-bit id for QinQ domain. P-VLAN is different from a
>> >customer vlans (C-VLANs) and as MPLS domain where several C-VLANs map into
>> >the same VPLS instance (represented by an ID), for QinQ domain several
>> >C-VLANs map into the same VPLS instance (represented by a 12-bit field).
>>
>>In this draft, there are two way to treat C-VLAN in MTU-rs:
>>1)if C-VLAN are not used as service delimiter, add P-VLAN.
>>      In this way, the isssue is that if two C-VLAN map into same P-VLAN, 
>> the PE-rs can only distinguish two customer by C-VLANs. But, the C-VLAN 
>> is untrusted, is not service delimiter. It is wrong for PE-rs to apply 
>> different value-add service for different C-VLANs.
>>     So it is better to map into different P-VLANs for differnent custom 
>> if the PE-rs want to distinguish them.
>>2)if C-VLAN are used as service delimiter, translating C-VLAN to a P-VLAN
>>     In this way, the issue is that if two C-VLAN are tranlated to one 
>> P-VLAN, the PE-rs will couldn't distinguish two customer.
>>      So it is better way to use different P-VLANs for different customers.
>
>I thought this has already been explained in the draft. If not it might 
>have been lost during editing. I will double check on this.
>
OK. Hope to add it, thanks.
To PE-rs,  P-VLAN is just looked as a AC , not be look as PW.  Many ACs can be  map to one VPLS-instance. So, many P-VLAN can map to one VPLS-instance also, even if these P-VLANs in one physical port.
If the MTU just map each customer to each P-VLAN, it become a VPWS/VLL. MAC learning is removed in MTU.    

>Thanks,
>Ali

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From: Ali Sajassi <[email-masked]>
Date: Tue, 15 Apr 2003 15:44:34 -0700

At 06:12 AM 4/16/2003 +0800, Du Wenhua wrote:
>To PE-rs,  P-VLAN is just looked as a AC , not be look as PW.  Many ACs 
>can be  map to one VPLS-instance. So, many P-VLAN can map to one 
>VPLS-instance also, even if these P-VLANs in one physical port.

No, that's not correct. Lets go over it one more time.

1) Unqualified learning: all traffic from a given customer is tagged by 
P-VLAN, so if a customer is connected to a given access network through 10 
different ACs (and through several different MTU-s), then all those ACs 
will be tagged by the same P-VLAN. The P-VLAN as mentioned before 
corresponds to a single VPLS instance. Thus, all C-VLANs for a that 
customer share the same MAC address domain and broadcast domain.

2) Qualified learning: each C-VLAN is represented by a P-VLAN. Thus a given 
C-VLAN (e.g., VLAN-10) over different ACs maps into a unique P-VLAN (e.g., 
VLAN-100) and that P-VLAN corresponds to a single VPLS instance.

Therefore, in both cases, a single P-VLAN correspond to a single VPLS 
instance and vise versa - e.g., one-to-one mapping.

-Ali

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From: Muneyoshi Suzuki <[email-masked]>
Date: Wed, 16 Apr 2003 10:16:48 +0900 (JST)

Ali,

> instance and vise versa - e.g., one-to-one mapping.

I'm not sure what is a VPLS instance in the above context, but if it 
means frame forwarding based on the P-VLAN ID value, I think, it may 
violate in-sequence delivery of frames.

Thanks,

Muneyoshi Suzuki
Nippon Telegraph and Telephone Corp.

---

From: Ali Sajassi <[email-masked]>
Date: Wed, 16 Apr 2003 09:21:05 -0700

>violate in-sequence delivery of frames.

For a description of VPLS instance in context of qualified and unqualified 
learning and its relationship to customer VLANs, please refer to sec. 8.1.1 
of the draft and then tell me why "it may violate in-sequence delivery". 
P-VLAN id just like a VPLS-instance id identifies a given FIB and the 
forwarding is done based on customer's MAC addresses within that FIB.

-Ali