In another mailing list, someone has asserted that "noone believes router vendors who say [they can support 2M routes today and 10M with no change in technology]". Or perhaps more accurately, the router vendors claiming this are being a bit disingenuous in that while it is possible routers can handle this many static routes, they'll quickly fall down if they were subjected to real world dynamic conditions ISPs would see if you extrapolate routing flux in today's tables up to (say) 2M routes.
My questions:
Do you believe router vendors who state they today have "capacities on the order of 2 million ipv4 routes and they have no reason to expect that they couldn't deliver 10 million route FIB products in a few years given sufficient demand."?
If you do not (or you believe the router vendors are being disingenuous) and routing system growth continues:
- where do you believe existing routing technology will fall down?
- what steps will you take/are you taking to limit your vulnerability?
Feel free to respond privately if you don't feel comfortable discussing this in a public forum. I promise to hold any responses confidential, publishing only a summary of responses.
In another mailing list, someone has asserted that "noone believes
router vendors who say [they can support 2M routes today and 10M with
no change in technology]".
Do you believe router vendors who state they today have "capacities
on the order of 2 million ipv4 routes and they have no reason to
expect that they couldn't deliver 10 million route FIB products in a
few years given sufficient demand."?
David,
NNTP is similar to BGP in that every message must spread to every
node. Usenet scaled up beyond what anyone thought it could. Sort of.
Its not exactly fast and enough messages are lost that someone had to
go invent "par2".
- where do you believe existing routing technology will fall down?
I guess you could say that I think BGP has an NNTP future. It never
quite breaks completely, it just gets worse and worse at doing its
job.
- what steps will you take/are you taking to limit your vulnerability?
As a multihomed endpoint network, I can sacrifice some reliability by
introducing a default route and filtering longer prefixes if I really
have to. I hope the folks upstream have a better answer.
Netnews was originally designed for 300 bps dial-up modems with O(1)
hubs. Fortunately, the technology evolved to meet the load. Will BGP
evolve that way? Netnews didn't demand anything more in common than a
file format, and the only major change in it was within 2-3 years after
it was invented. BGP doesn't have that property.
Well, to get specific, I think that it will be interesting to see what
happens when the size of the route table exceeds the stock TCAM on the Cisco
Catalyst platform. Before I got to my current employer Cisco sold then
7604s with Sup32s (I hope they weren't more expensive than 6504 chassis
because all they did was change the paint). I'm going to hope that Cisco
comes out with a Sup upgrade that includes the larger TCAM of the 3BXL
without the switch fabric mojo - that's stuff's expensive. The whole thing
really makes me wonder about the value of selling the Cat platform as a
customer edge router...
Its a great sale; they suddenly have hard limits which "the internet exceeds",
forcing the hardware upgrade cycle. Remember how long the Cisco 75xx persisted
and note how many people are still running Cisco 720x's with NPE-225's or
NPE-400's w/ full tables simply by adding RAM.
In another mailing list, someone has asserted that "noone believes
router vendors who say [they can support 2M routes today and 10M with
no change in technology]".
Can you tell us who said this on which email list?
Or perhaps more accurately, the router
vendors claiming this are being a bit disingenuous in that while it
is possible routers can handle this many static routes, they'll
quickly fall down if they were subjected to real world dynamic
conditions ISPs would see if you extrapolate routing flux in today's
tables up to (say) 2M routes.
I remember quite clearly at a much earlier meeting the statement that
"obviously the Internet will keel over dead if the top level IP routing
table reaches 10,000 entries" (this is not an exact quote, but the
"10,000" limit was what was stated at the time). At the time no one
challenged this observation, although at the time I did wonder why
someone thought that this was obviously true. Of course this statement
has been obviously false for quite a few years.
Sadly, I don't recall whether this statement was made at a very early
IETF, or at a GADS (gateway algorithms and data structures) meeting,
which was the group that preceded the IETF ("gateway" was an early word
for "router").
Of course, over the years there have been improvements in both
implementations and protocols to make the growth from "less than 10,000"
to "more than 200,000" work okay. I don't think that anyone is expecting
that today's routers will work with 10,000,000 top level Internet routes
without any change at all in any aspect of the implementation.
I think the context of (the other) David's question was wether or not
there need to be any changes in technology.
In that context, I don't think NNTP is a good analogy to prove the
point that no changes in technology are necessary.
NNTP acheived its ends in large part due to a protocol update for
'streaming' feeds - the CHECK and TAKETHIS commands to de-synchronize
sender and receiver (supplanting 'IHAVE' and 'SENDME') allowed servers
to fill the socket buffer and make full use of TCP large-window and
selective-ACK. I do not think I overstate the importance of this
change to call it an 'NNTP rewrite'; it literally reversed NNTP's core
design. There was at least one company that sold commercial NNTP
software - and provided a catalyst that caused most other software to
reflect upon itself and redesign core processes. Virtually all
software changed significantly (and there's some debate wether it was
for the better).
But the biggest part of NNTP's survival, I think, were the behind the
scenes news mega hubs - expensive machines with a lot of memory
bandwidth, solid state disks, and fat network connections, taking and
giving feeds to anyone who would ask. Some (most I think) were
operated at a loss - purely to support the network.
In another mailing list, someone has asserted that "noone believes
router vendors who say [they can support 2M routes today and 10M with
no change in technology]".
Can you tell us who said this on which email list?
The discussion was occurring on the ARIN PPML list.
I remember quite clearly at a much earlier meeting the statement that
"obviously the Internet will keel over dead if the top level IP routing
table reaches 10,000 entries" (this is not an exact quote, but the
"10,000" limit was what was stated at the time). At the time no one
challenged this observation, although at the time I did wonder why
someone thought that this was obviously true. Of course this statement
has been obviously false for quite a few years.
Yes, and I remember when quite a few folks were doing "ISP code release of the day" to ISPs whose routers were having "issues" because of the routing load (ah, the good old days :-)).
Of course, over the years there have been improvements in both
implementations and protocols to make the growth from "less than 10,000"
to "more than 200,000" work okay. I don't think that anyone is expecting
that today's routers will work with 10,000,000 top level Internet routes
without any change at all in any aspect of the implementation.
"In the case of Cisco that means delivering switch routers with a capacity of about a million routes now. In the case of Foundry they are projecting that with some FIB aggregation techniques that switches capable of 512k fib entries will still be usable by 2014. Juniper is delivering new products (m120 mx960) with DRAM rather than TCAM/SRAM based FIB's with capacities on the order of 2 million ipv4 routes and they have no reason to expect that they couldn't deliver 10 million route FIB products in a few years given sufficient demand."
The question I am asking is whether or not folks in the operational community believe these statements are accurate or realistic in the face of real world Internet dynamics. I know some people do not. I'm trying to get a feel from the wider community as I am in no position to judge.
Adrian Chadd writes [on Cisco's TCAM-based 7600/Cat6500 routers]:
Its a great sale; they suddenly have hard limits which "the internet
exceeds", forcing the hardware upgrade cycle. Remember how long the
Cisco 75xx persisted and note how many people are still running
Cisco 720x's with NPE-225's or NPE-400's w/ full tables simply by
adding RAM.
"Simply adding RAM" may not be that easy/cheap, especially when you
have to upgrade it on many linecards (VIP2s anyone?). On distributed
platforms with hardware forwarding in the linecards (GSR) this is/was
probably even worse, you have these "hard limits" in the linecards.
Replacing centralized switching engines from time to time doesn't
seem such a bad value proposition compared to
replacing/memory-upgrading line cards.
Yes, but people -are- still acquiring VIP2-80's and such, maxing them
out with RAM, and deploying them in the network. You might not see it
in the US as much but, if c-nsp is anything to go by, they're quite
popular in "internet developing" nations.
People are "simply adding RAM" to older routers to squeeze the last
few cents. Then you get people that'll quite happily throw on BGP
filters to drop down the table/FIB size and use a default to get
to the rest. Or people doing similar tricks on Cisco 3550 L3 switches.
In any case, I was primarily referring to the staying power of the
non-distributed Cisco forwarding platforms.
> In another mailing list, someone has asserted that "noone believes
> router vendors who say [they can support 2M routes today and 10M with
> no change in technology]".
Can you tell us who said this on which email list?
In terms of the original statement, we were also given this
presentation during the routing working group of the most recent RIPE
meeting:
dire predictions of the MSFC2 "topping out" have occured
on this list. anyone want to SWAG the number of MSFC2's
are in use today? It might be nice to also extrapolate
that number as a percentage of total routing engines... but
thats an even larger SWAG.
if the number is roughly the same as the number of AGS+ boxen
in use, i'm less worried