At 06:48 AM 4/6/2001 +0200, Hank Nussbacher wrote:
>In Juniper one needs a Tunnel PIC:
>http://www.juniper.net/techpubs/hardware/m160/m160-picinstall/html/pic-description21.html
>in order to create GRE or IP/IP tunnels. What exactly is so special in
>managing a tunnel that one needs a special line card as compared to IOS
>that provides tunnel support for free in IOS?
In IOS they do it via the processor. There is no processor in the M-series
forwarding path. To be able to modify the packet twice you need to loop it
through the Internet Processor twice. This is what the Tunnel PIC does.
And, as Avi pointed out, it is good for up to ~1Gb of tunnel encap/decap
per Tunnel PIC with no performance hit and you can have more than one
Tunnel PIC per chassis.
> Do most ISPs buy the tunnel
>PIC when ordering a router or do you wait till a tunnel is needed?
Depends on how hard it is to get to the router to install the Tunnel PIC
when it becomes needed and how long it will be before they think they will
need it. And how well they can stand the delay from when they decide they
need it and when they would actually be able to cut the PO/get the
PIC/install the PIC.
GK
GK
>Thanks,
>Hank
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