Re: Speeds and feeds

From: Ryan Russell (ryanrat_private)
Date: Fri May 29 1998 - 11:02:05 PDT

  • Next message: George Ross: "Re: Identifying End of Tx in FTP"

    T3's are nice if you can afford them, and that's really
    the deciding factor, cost.
    You haven't mentioned any layer 1/2 soultions, i.e.
    muxing 2 or more T1's together.  Most ISPs support
    that, and it's transparent to the layer 3 setup.  You
    do tend to halve your MTBF when you mux two
    T1s, so make sure the muxing arrangement you
    make can deal with one of them going out.  Also,
    it forces you to use only 1 ISP, which might be bad
    if you were hoping to get some redundancy that way.
    Other ways (which you've mentioned) are to use seperate
    T1s for seperate purposes.. I did that for a while.  My
    "incoming traffic" such as people hitting my web sites
    and sending me mail came in one pipe, by virtue of the
    fact that I had a seperate IP range on it.  The other pipe
    was for my users to "surf."  Different ISPs, different address
    ranges, no problem.  The problems are fairly obvious.. when
    one pipe goes over, I can't take advantage of spare
    bandwidth on the other.  When I lose one pipe, I lose it's
    function, because it typically takes to long to switch routes.
    It may be viable to switch routes if you stick with one ISP,
    and both pipes go to the same or nearby POPs.
    I got rid of that soultion because I got T3's.
    I don't really have the experiece to speak to BGP routing
    I'm working with a company currently using a T1 which becomes very
    sluggish when engineers do many FTP and HTTP sessions through a state
    firewall on a Netra-1 (firewall is not a bottleneck).  They're thinking
    of upgrading to a T3 with a fast proxy server (+ VPN) since they also
    are running out of IPs, and internal systems are getting hit by external
    My knee-jerk reaction is to use a very fast CPU system (600MHz Alpha)
    and Altavista FW with 100Mbps cards.
      Internet--(T3)---R1---FW---+----R2----Internal LAN
                             Tunnel Svr
    I'm wondering about alternatives to the situation, one is multiple T1s
    coming into a set of BGP net for redundancy, and to partition FTP/HTTP
    proxies on one server, and remaining traffic on a second server
    (allowing future cluster or fail-over via scripts and IP failover of
    secondaries).  Although this actually may be cheaper, faster and more
    reliable, but it's more complex, and harder for the company to fix if it
    dies (fails into a degraded mode).  Also most local traffic may route
    through a single T1, and they may inadvertantly become an Internet
        | | |
       (n+1 T1s)
        | | |
      Cisco 2500s
        | | |
        |    |
     FW-A   FW-B
    FW-A could be used for outbound client system access, and FW-B could be
    used for inbound/server protocols (VPN, webserver SQL, NTP, SMTP, DNS,
    etc).  A dual-subnet webfarm could connect to third interface on both.
    Hmm, too complex maybe.
    Bill Stout
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    Date: Tue, 26 May 1998 14:06:42 -0400
    From: "Stout, Bill" <>
    Subject: Speeds and feeds
    To: Firewall-wizards <firewall-wizardsat_private>
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