How ISP distinguish between Metropolitan and External traffic?

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Jul 13th, 2009
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Hello,


I want to limit bandwith for my subnets

I have from my ISP: 10Mb for Metropolitan and 4MB for External. I did limit traffic for one subnet to 1MB. But this limitation is affecting also the Metropolitan traffic.

I want to limit to 1MB for that subnet for External traffic only, but for Metropolitan traffic I want no limitation(to be able tu use all 10MB)


Do u know how ISP make this separation between Metro and Extern traffic? Maybe I can use the same method.


Thnaks

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Joseph W. Doherty Wed, 07/15/2009 - 04:39
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"Do u know how ISP make this separation between Metro and Extern traffic? Maybe I can use the same method. "


Do I know how your ISP makes this distinction, no, and even if we did, and you could do likewise, it might not be your best option. This because your ISP might be enforcing such limits by policing.


For you, your best option might be making an distinction on destination (outbound) addressing, between "Metropolitan" and "External", then shaping such for 10 and 4 Mbps, respectively.


How does your ISP define these two?


NB: If both "Metropolitan" and "External" are Internet traffic, but your ISP makes a distinction based on a using a local Internet exchange point or other local ISP BGP peering agreements, it could be very difficult for you to mimic their policy without knowing your ISP's local BGP topology.


PS:

It's clear why you want to use all 10 Mbps for "Metropolitan traffic", and why you wouldn't want to mix limitation of one with the other, but why do you want to limit "External traffic", or some subnet, to just 1 Mbps when you have 4 Mbps?

Spinu Viorel Wed, 07/15/2009 - 11:28
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I have 4 subnets: A, B, C, D

Subnet A must not go above 1MB

Subnet B must not go above 200kbits

Subnet C must not go above 2MB

Subnet D the rest of the bw


I don't want subnet C to go above those 2MB and steal the bandwidth from subnet A.


I don't understand one thing: how can I make a distinction on destination addresses? This means that I have to know all the IP addresses of my country and define those as Metropolitan?


U are right. I found out that my ISP makes the distintion between Metropolitan and External based on their own IP addresses and based on BGP peering agreements with other ISP from my country. So this is not the solution for me.


Thamk u for answering! This was an old dilema for me.


Joseph W. Doherty Wed, 07/15/2009 - 12:03
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"how can I make a distinction on destination addresses? This means that I have to know all the IP addresses of my country and define those as Metropolitan? "


Well not all address, but address blocks. This could have worked if "Metropolitan" was something like Metro Ethernet, and private addressing. Not so, based on BGP peering agreements.


BTW, you could still manage bandwidth between your subnets based on their souce addresses. However, what would still be a problem whether the overall cap should be 4 or 10 Mbps.

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