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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: QoS for ADSL customers
On Wed, 30 Nov 2005, Joe Shen wrote: > To Kim's situation, IP packet header based (or access > interface based) traffic classification is pratical. > If application based traffic classification is > required, tools from sandvine or packeteer may have to > be sitted between ERX1440 and Cisco7609. IMHO, ISP > network should NOT trust any TOS/DSCP set by their > customers; so, classifying and (re)tagging must be > done in PE or BRAS. On the other hand, anti-spoofing > configuration must be enabled in ERX1440 or 7609. > Anyway, I don't trust current router's ability on > content based traffic delivery. The problem with waiting until the PE or BRAS to do the classification is most access providers use traffic aggregation in the access network (e.g. ATM/DSL, Cable, WiFi, etc). This means the interfaces on the BRAS or PE are oversubscribed and the access network interface will experience inbound cell/frame drops. If you don't trust the router's ability, imagine a dslam's ability to do it at the ATM layer. Some networks let users tag their traffic, other networks re-tag all traffic according the network's policies. At the moment it seems to be a business decision. But the result is users shouldn't expect unmangled TOS/DSCP bits over the Internet. Coordinating the IP layer QOS with the access network/physical layer QOS is a bit of a challenge.
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