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Re: Film at 11:00
From: alex () relcom EU net
Date: Wed, 1 Jan 97 18:56:57 +0300

BTW, really all data incorporated from BGP protocl for
3 - 8 core routings do not need more than 32MB RAM; the fact CISCO
need more than 32MB ram for core routing is due to inefficient data
structures... Exactly it's because they (I think) have solved some
other task (not minimize memory, but CPU and development time).

What is really 100K routes?

100K * (
        8 bytes - address + maska
        4 - pointer to interface
        4 - pointer to ASPATH (ASPATHES are really shared by many
                different routes; You have not 1000,000 different AS
                PATHES at all)
        8 - accounting
        8 - some other,

) - it's about 32 bytes in this example.

Of cource, it's not true - really we can expect about 64 bytes/route.

64 bytes * 100K = 6 Mb RAM. I can propose it's nessesary 128bytes - it'll be
12MB RAM.

But anyway, if somebody designes specially INTERNET CORE router,
he can hold any core routing tables in 16 MB RAM, not more. There is
a lot of different ways to minimise memory usage.

We are far from the theoretical memory leak; the more serious problem
may be efficiensy etc..., but there is CISCO FUTIONS and other ideas
to hold CPU usage in acceptable range.

I am shure we'll be the witnesses of the such events as it have been last
year when CISCO's engeneers have fixed serious BGP problem in 1 or 2
nights. Through this way (to solve hardware problems by software)
have it's limits.



--- 
Aleksei Roudnev, Network Operations Center, Relcom, Moscow
(+7 095) 194-19-95 (Network Operations Center Hot Line),(+7 095) 239-10-10, N 13729 (pager)
(+7 095) 196-72-12 (Support), (+7 095) 194-33-28 (Fax)
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