[nsp] Dual homing without BGP

From: Martin Picard (mpicard@sinc.ca)
Date: Thu Feb 22 2001 - 19:42:01 EST


Hi,

  From an ASP redundancy standpoint, dual homing to
  two different providers is essential. Most of the times
  a small block of IP addresses is required (from one of
  the Upstream ISP). In order to be fully redundant, this
  block has to be propagated through the internet by
  both Upstream ISPs. I understand that this causes
  some "non-summarized" routes to be advertised but
  are there any other choices ?!
  Assuming not, both providers will advertise the prefix.
  The issue of wether or not one agrees to have a more
  specific prefix to advertise and also allow others to
  advertise it puzzles me but moreover is the way to do
  it.

  It seems that when we're talking BGP peering, there's
  no problem, everybody can advertise whatever.
  Again, from an ASP standpoint that only has a local
  LAN of servers with redundant routers to get to the
  internet, the full knowledge of all Internet routes is
  useless. Granted that the ASP can filter out all routes
  if so desired and that BGP can be used only to
  provide the Internet the paths to the ASP. But does
  it absolutely require that the ASP runs eBGP with
  both providers. I mean, both providers can inject
  the ASP prefix in the Internet and the ASP just
  default to one or the other. If BGP is the only option,
  I just can't imagine the number of ASNs required
  to support all upcoming ASPs and I don't see any
  technical reasons why it cannot be otherwise.

  I am probably missing something...
  Please enlight me !!!

  tx
  martin



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