Route leak in Bangladesh

Wed Jul 1 14:57:21 UTC 2015

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.