Multiple vendor ISPs and multihoming and QoS route optimization

[Abzstrak]

ok guys (and gals), the more I read about doing this the more I dont know...

for example, when a client has 4 T1's all from different vendors, is it all the same IP range? if so how can the ISPs that dont own the range use the range of someone else? if its not the same range how do they handle simple things like DNS resolution?

Also, where are qos route optimization devices setup? are they on the perimeter of each WAN line from each vendor? or is there another router before these routing to the proper link?

Also in the QoS is it possible to have the return path be different than the transmitting one? if so how does this work?

anyways can someone gimme a quick and dirty run through on this stuff (if one exists ;-)

and does anyone have some good links where I can do alot of reading?

TIA

 

[Shockwave]

First off, lemme say I'm just guessin on most of this...

Why would a client want multiple vendors? And more importantly, why use links from mulitple vendors at the same time. I would think that would be a nightmare to get working. I can see 4 T1's, with a back up service from another vendor. Anyways, I would assume route optimization would happen on the ISP's network, not on site, simply because all links will have to run through the LEC. ISP's dont run new wiring, they just run through LEC (unless you got ALOT fo money). In which case, your essentially having a static route until you get off the local loop. I would say you shouldnt have different rc/tx paths, however I have seen cases where a edge switch will be transmitting on working and recieving on protect, however it shouldnt be doing this and is considered a problem. But, in by what you've said (ISP) I assume you mean this is IP traffic, in which case the route wont be static, so different rc / tx really isnt an option, as the packets may not take the same path anyways, unless perhaps your doin IP tunneling or something. Keep in mind I dont deal with IP traffic, so i dont understand all the wonderful details.
So, thats my thoughts, which probably doesnt help ya much, but I had fun typin...🙂

 

[spidey07]

You announce your AS (networks) with BGP (internet routing protocol). Route selection is then based on your upstream providers and any kind of agreement you have with them. You can do all sorts of things with BGP to mark certain routes and prefer others. You most certainly can have return traffic follow a different path - called asymetric routing and it happens all the time.

I've never really heard of QoS and routing being used together. That is where MPLS and RSVP come into play.
quick link