[c-nsp] Dual-homing without BGP

Vincent De Keyzer vincent at dekeyzer.net
Thu Feb 16 09:55:21 EST 2006



can you please review the following suggestion ?



*         Customer is a communications agency (i.e. more "content" than

*         They are doing serious things like e-commerce on the Internet
connection they have with provider T (like 'trusted'). It's a 2M line.

*         They have a /23 which is announced as such on the global BGP
network by provider T (although it's part of one of T's /16s)

*         They are considering to buy a second Internet link at 25 Mbps from
provider N (like 'new'), on which they plan to do less serious things like
video streaming.

*         They also want to have some redundancy: if T link goes down,
traffic goes out via N - but if N goes down, they don't want streaming to
clog the limited T bandwidth, so no streaming in that case.


Would the following solution work?

1.       Customer have a router that would NOT run BGP (in order to limit
investment), and that would be connected to N, T and servers LAN.

2.       N would also announce the /23 to the world.

3.       If link to T or N fails, T or N respectively stop announcing the

4.       With a combination of PBR (which I am not too familiar with) and
floating routes, they would control on which link traffic will go out (based
on server source address) according to the last requirement above.


What do you think?





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