n**********l
发帖数: 271 | 1 Is it possible for discontiguous networks (for example, multiple datacenters
across the world) to use the same ASN? A private backbone connecting them
is a must?
Route reflector does not solve the discontiguous problem, does it?
I was asked a bunch of questions for a CDN network and last night I realized
everything I said would make no sense if it has a noncontiguous backbone.
AS65000 East coast datacenter -- AS 100 (Upstream1) -- AS65000 West coast
datacenter
AS65000 East coast datacenter -- AS 200 (Upstream2) -- AS65000 West coast
datacenter
Without a private backbone, blackhole is very likely to happen. And even
with a private backbone, hauling traffic around is expensive and it is
essentially someone else's (transit providers etc.) work.
How do CDNs(Akamai, Netflix etc.) use BGP? Route reflector/modifying next-
hop?
I am quite confused. | s*****g
发帖数: 1055 | 2 A basic BGP feature "bgp allow-as in" will allow prefixes with its own AS in
AS-PATH into local BGP/routing table, by-pass BGP's loop-avoidance
algorithm, so to speak. Is this what you are asking? or if you are not multi
-homing, you just import default route from your local ISP.
Unless you are tier-1 ISP, you most probably don't need your own transport.
For Netflix's CDN, read their "open-connect" white paper, nothing fancy at
all.
datacenters
realized
【在 n**********l 的大作中提到】
: Is it possible for discontiguous networks (for example, multiple datacenters
: across the world) to use the same ASN? A private backbone connecting them
: is a must?
: Route reflector does not solve the discontiguous problem, does it?
: I was asked a bunch of questions for a CDN network and last night I realized
: everything I said would make no sense if it has a noncontiguous backbone.
: AS65000 East coast datacenter -- AS 100 (Upstream1) -- AS65000 West coast
: datacenter
: AS65000 East coast datacenter -- AS 200 (Upstream2) -- AS65000 West coast
: datacenter
| x*********n
发帖数: 28013 | 3 你要从头理解它。
AS本来就是一个virtual的concept，和area一样。
现在你几个location是一个company，你用什么iBGP还是eBGP？
iBGP require direct connection吗？为啥你config iBGP的时候不用改TTL？
后面的问题你应该都知道的，那就是自问自答了，呵呵。
再说RR，为什么要RR，是因为full mesh database大，那跟next-hop有什么关系？ | n**********l
发帖数: 271 | 4 一个interview BGP diagram里面sites之间没有link, 直接连upstream
我就看得莫名其妙的了....估计答的大都错了....
【在 x*********n 的大作中提到】
: 你要从头理解它。
: AS本来就是一个virtual的concept，和area一样。
: 现在你几个location是一个company，你用什么iBGP还是eBGP？
: iBGP require direct connection吗？为啥你config iBGP的时候不用改TTL？
: 后面的问题你应该都知道的，那就是自问自答了，呵呵。
: 再说RR，为什么要RR，是因为full mesh database大，那跟next-hop有什么关系？
| x*********n
发帖数: 28013 | 5 eBGP needs to directly connected, iBGP doesn't
eBGP 不directly connected也能peer，3种方式，一种是常见的emulti-hop，一种是
disconnected，一种是TTL-max啥的，总之都是改TTL。
BGP是over TCP的，你想啊，这都是在layer 4了，底层是要有IGP running的。
synchronation都是要和IGP match才能做BGP的。
你可以把interview题目发上来，大家帮你看看，弄清楚了，下次就不会错了。
【在 n**********l 的大作中提到】
: 一个interview BGP diagram里面sites之间没有link, 直接连upstream
: 我就看得莫名其妙的了....估计答的大都错了....
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