[Irtf-rr] Just an idea for a self organiziong IPv6 address space network
Jing Shen
jshen_cad@yahoo.com.cn
Thu, 7 Nov 2002 11:11:39 +0800 (CST)
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Hi all,
the situation Yang thought about is the situation some ISPs do with their customers who are
small companies. These companies just want to access the internet with acceptable access speed
but with limited budget. So, they just buy some IP address from ISP and lease line with low speed ( as I know
it's usually under 1Mbps). But the situation changes when ADSL and LAN access come into market. By using monitoring
tools, ADSL could be kept up nearly all the time , and by using NAT and ADSL (or 10Mbps ethernet LAN), small companies
can easily set up their internet connection, and with help of DynaDNS they can even set up web service, email service etc.
So, more and more small companies abandon the old way of paying for a block of IP address in ISP network.
The second, from the point of view of routing, AS enables a reliable and dynamic routing ability in internet. The path vector
is exchanged and stored in routers while only the 'best' one is used. This means, no matter a company's network
is single homed or multi-homed it can rely on the BGP to get a fulltime connection, with help of policy based routing some commercial
policy could be applied too. Within AS, OSPF/IS-IS could be used to establish best paths.
To the extrem situation, if a customer hire two leased line from two ISP, and each ISP allocate a block of ip address to the customer,
policy based routing and NAT could guarantee the internet access but a block of IP address is wasted. I think this situation is the one
considered by Yang, and maybe he's thinking about a solution by routing. But I think this could solved by using solution using
(DHCP, network monitoring, two or more IP block from two AS, two or more leased line). In this solution, a DHCP server hold all
addresses and monitors outgoing lines, when a computer comes up the DHCP server allocate ip address according to state of leased
lines. The access router just need to set up static routing table ( maybe NAT). The problem exists with those servers, who could not
change its ip address from time to time and the cost.
So, to my opinion it's not a good idea to allocate IP addres hierachically and a peer connection between AS is a good solution.
regards
Xiaowei Yang <yxw@cordelia.lcs.mit.edu> 的正文： Thanks for the explanations and for the pointers. I agree that
dynamically allocating IP addresses is not desirable in practice, but
I do think it is possible to "statically" allocate provider-rooted
hierarchical addresses. (I was not the one originating the thread, but
my thesis work is related to the topic.)
What I mean by "statically" is that once a provider-customer
relationship is established, the customer is allocated a fixed address
block from the provider. A multi-homed customer will be allocated one
or more address blocks from each of its providers.
I agree that there might be reluctance to adopt this approach. This
is a general problem discussed in Shenker et al's paper on algorithmic
mechanism design. In a distributed system like Internet, we can not
simply expect that each AS cares about the stability and scalability
of BGP and will follow the protocols we design. Each AS will act
selfishly, but we can design protocols with incentives for an AS to
follow.
As an example, if an global address prefix costs a significant amount
of fortune, perhaps many small networks / local ISPs are willing to
take address blocks from their providers. If becoming a visible entry
in the global BGP table costs money, perhaps many networks would want
to be aggregated into their providers' entries.
By this allocation, ISPs can still operate if the rest of the Internet
collapses, because dynamic failures do not terminate the business
relationships and do not change the address blocks a domain owns.
We do not need algorithms to determine which ASes are the top level
ones. Whichever affords the money can buy a global unique address
prefix.
Due to the hierarchical aggregation, some dynamic failure will be
hidden from outside the address blocks. Thus, the end system itself
will need to have some error recovery mechanisms. Once an address
fails, it tries another one.
Kleinrock's hierarchical routing scheme cannot be directly applied to
the Internet. In Kleinrock's work, there is no "policy routing"
involved. Each node is willing to provide transit service for each
other. Thus, the cluster boundaries can be formed easily. In Internet,
due to policy routing, there is no natural way of forming clusters.
However, landmark routing can be applied to the Internet. This
hierarchical allocation scheme can be viewed as a variant of landmark
routing. A provider is the landmark for a customer. Packets are routed
towards the landmarks unless a better route is heard.
Jing Shen
State Key Lab of CAD&CG
ZheJiang University(YuQuan)
HangZhou, ZheJiang Province 310027
P.R.China
---------------------------------
Do You Yahoo!?
"是IT精英吗？小试牛刀获时尚大奖！"
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<P> Hi all,
<P>the situation Yang thought about is the situation some ISPs do with their customers who are
<P>small companies. These companies just want to access the internet with acceptable access speed
<P>but with limited budget. So, they just buy some IP address from ISP and lease line with low speed ( as I know
<P>it's usually under 1Mbps). But the situation changes when ADSL and LAN access come into market. By using monitoring
<P>tools, ADSL could be kept up nearly all the time , and by using NAT and ADSL (or 10Mbps ethernet LAN), small companies
<P> can easily set up their internet connection, and with help of DynaDNS they can even set up web service, email service etc.
<P>So, more and more small companies abandon the old way of paying for a block of IP address in ISP network.
<P>The second, from the point of view of routing, AS enables a reliable and dynamic routing ability in internet. The path vector
<P>is exchanged and stored in routers while only the 'best' one is used. This means, no matter a company's network
<P>is single homed or multi-homed it can rely on the BGP to get a fulltime connection, with help of policy based routing some commercial
<P>policy could be applied too. Within AS, OSPF/IS-IS could be used to establish best paths.
<P>To the extrem situation, if a customer hire two leased line from two ISP, and each ISP allocate a block of ip address to the customer,
<P>policy based routing and NAT could guarantee the internet access but a block of IP address is wasted. I think this situation is the one
<P>considered by Yang, and maybe he's thinking about a solution by routing. But I think this could solved by using solution using
<P>(DHCP, network monitoring, two or more IP block from two AS, two or more leased line). In this solution, a DHCP server hold all
<P>addresses and monitors outgoing lines, when a computer comes up the DHCP server allocate ip address according to state of leased
<P>lines. The access router just need to set up static routing table ( maybe NAT). The problem exists with those servers, who could not
<P>change its ip address from time to time and the cost.
<P>So, to my opinion it's not a good idea to allocate IP addres hierachically and a peer connection between AS is a good solution.
<P>regards
<P> <B>Xiaowei Yang <yxw@cordelia.lcs.mit.edu></B> 的正文：
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #1010ff 2px solid">Thanks for the explanations and for the pointers. I agree that<BR>dynamically allocating IP addresses is not desirable in practice, but<BR>I do think it is possible to "statically" allocate provider-rooted<BR>hierarchical addresses. (I was not the one originating the thread, but<BR>my thesis work is related to the topic.)<BR><BR>What I mean by "statically" is that once a provider-customer<BR>relationship is established, the customer is allocated a fixed address<BR>block from the provider. A multi-homed customer will be allocated one<BR>or more address blocks from each of its providers.<BR><BR>I agree that there might be reluctance to adopt this approach. This<BR>is a general problem discussed in Shenker et al's paper on algorithmic<BR>mechanism design. In a distributed system like Internet, we can not<BR>simply expect that each AS cares about the stability and scalability<BR>of BGP and will follow the protocols we design. Each AS will act<BR>selfishly, but we can design protocols with incentives for an AS to<BR>follow.<BR><BR>As an example, if an global address prefix costs a significant amount<BR>of fortune, perhaps many small networks / local ISPs are willing to<BR>take address blocks from their providers. If becoming a visible entry<BR>in the global BGP table costs money, perhaps many networks would want<BR>to be aggregated into their providers' entries.<BR><BR>By this allocation, ISPs can still operate if the rest of the Internet<BR>collapses, because dynamic failures do not terminate the business<BR>relationships and do not change the address blocks a domain owns.<BR><BR>We do not need algorithms to determine which ASes are the top level<BR>ones. Whichever affords the money can buy a global unique address<BR>prefix.<BR><BR>Due to the hierarchical aggregation, some dynamic failure will be<BR>hidden from outside the address blocks. Thus, the end system itself<BR>will need to have some error recovery mechanisms. Once an address<BR>fails, it tries another one.<BR><BR>Kleinrock's hierarchical routing scheme cannot be directly applied to<BR>the Internet. In Kleinrock's work, there is no "policy routing"<BR>involved. Each node is willing to provide transit service for each<BR>other. Thus, the cluster boundaries can be formed easily. In Internet,<BR>due to policy routing, there is no natural way of forming clusters.<BR><BR>However, landmark routing can be applied to the Internet. This<BR>hierarchical allocation scheme can be viewed as a variant of landmark<BR>routing. A provider is the landmark for a customer. Packets are routed<BR>towards the landmarks unless a better route is heard.<BR><BR><BR></BLOCKQUOTE><BR><BR>Jing Shen<br><br>State Key Lab of CAD&CG<br>ZheJiang University(YuQuan)<br>HangZhou, ZheJiang Province 310027<br>P.R.China<p><br><hr size=1><b>Do You Yahoo!?</b><br>
<a href="http://rd.yahoo.com/mail_cn/tag/?http://cn.promo.yahoo.com/cgi-bin/udb/u">"是IT精英吗？小试牛刀获时尚大奖！"</a>
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