Re: [IPsec] One comment to this draft//Fwd: I-D Action: draft-ietf-ipsecme-ad-vpn-problem-06.txt

Hi Toby.

Let's see if I understand the issue. I'll describe this with an example. Please let me know if I got it.

Suppose we have satellite gateways A, B, C, D, and E. A through D each have a bandwidth of 10 Mb/s, while E has 20 Mb/s.

The center gateway, Z, has plenty of bandwidth and the appropriate QoS policy. So if A, B, and C are simultaneously sending traffic to E through Z, Z will do the QoS magic (maybe by dropping packets or playing with TCP ACKs) to make sure the QoS goals are met.

Now add ADVPN to the mix. A and E discover each other, and are able to bypass Z. Initially A had no IPsec policy about E. There's no reason to think it had a QoS policy about E, and the same is true in the other direction. Unless the QoS policy from Z somehow gets transmitted to the satellites, they may reach congestion and have the QoS targets miss.

So whereas before ADVPN the center gateway could be counted on to handle the QoS (because everything goes through it), as soon as you add ADVPN, that policy has to be enforced on the spokes, or not at all.

I'm not sure whether we can or should solve this issue as part of AD-VPN, but I want to make sure that we understand the issue.

Yoav

On May 2, 2013, at 6:02 PM, Toby Mao <yumao9@gmail.com<mailto:yumao9@gmail.com>> wrote:

On Sat, Apr 27, 2013 at 10:57 PM, Paul Hoffman <paul.hoffman@vpnc.org<mailto:paul.hoffman@vpnc.org>> wrote:
These requirements might be useful to add in the next draft, but they need to be refined.

On Apr 26, 2013, at 8:10 PM, Toby Mao <yumao9@gmail.com<mailto:yumao9@gmail.com>> wrote:

> The ADVPN solution SHOULD be able to implement Quality of Service (QoS) to regulate the traffic in the ADVPN topology.

Why is this statement needed? Do you see situations where an ADVPN solution would be *prevented* from implementing some sort of QoS because it was an ADVPN?

 [Toby]: There is no situation that ADVPN solution could be prevented from implementing Qos. Actually, Qos is crucial on ADVPN, such as sharing network bandwidth, meeting the application latency requirement. Especially in the Hub, for each spoke, the Qos policy should be implemented individually , because different spoke has different link speed and data processing capability. Thus, in the ADVPN solution, the small spoke can not be overrun by hub by sending too much traffic, also the spoke which has large bandwidth cannot hog the hub's resources and starve other spokes. In addition, a unique Qos policy for each spoke in the hub could be cumbersome for administrator, some improvement could be implemented, such as the spokes with the same bandwidth can belong to the same group, the Qos policy can be implemented on a basis of group.

> ADVPN peer SHOULD NOT send excessive traffic to the other members of ADVPN.

How would you define "excessive"? Where would that measurement be done?

[Toby]  The traffic to the ADVPN peer exceeding the actual peer bandwidth can be defined as "excessive". To solve this problem, the other ADVPN peer should apply Qos policy for this ADVPN peer.

> The traffic for each ADVPN peer CAN be measured individually for shaping and policing.

Why is this statement needed? Do you see situations where an ADVPN solution would be *prevented* from measuring individually?

[Toby]  The reason is explained in the first answer.

--Paul Hoffman

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