nanog mailing list archives

Re: Route leak in Bangladesh


From: Mark Tinka <mark.tinka () seacom mu>
Date: Wed, 1 Jul 2015 16:57:21 +0200



On 1/Jul/15 16:52, Nick Hilliard wrote:
This is a strange sort of thing really.  There's no reason that a compiled
prefix list of 250k entries should take up much RAM in a trie structure;
there's no reason that a competently written parser shouldn't be able to
handle 20 megs of prefix lists / sets in a trivial amount of time and
there's no reason that writing a 20 meg configuration file should take long
to write to disk / flash / etc.

BIRD handles this in ultraquick time.  Even recent versions of Quagga can
now suck + parse 10 megs of prefix filters in a second or two and write
them out in less.

But Junos / IOS / XR puke horribly.  What gives?

Nick, I think the concerns are two-fold:

    1. The time it takes to process the trie.
    2. How much physical space there is to support the configuration.

Remember some high-end Cisco routers only have 2MB of NVRAM. This could
get tested with a large prefix-list configuration. Junos may not have
much of a space issue since the configuration is stored on the compact
flash or HDD.

Trie compilation or process will be very OS-dependent, and how the
vendor has chosen to optimize that operation.

Mark.


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