Well I was kind of wondering what variable maximum meant! &;-)
Seriously, I just checked IEEE 802.5 and it doesn't specify a maximum frame
size. It just says that the maximum token holding timer is 8.9
milliseconds. A station can hold onto the token while sending its bits for
a maximum of 8.9 milliseconds. After 8.9 milliseconds, it must relinquish
control of the token. So here's the math:
4 Mbps = 4000 bits in a millisecond
In 8.9 milliseconds a station could send 8.9 x 4000 bits = 35600 bits
35600/8 = 4450 bytes
For 16 Mbps, the max frame size = 4450 x 4 = 17800 bytes
QED
Priscilla
At 08:15 AM 9/18/00, John Barnes wrote:
>----- Original Message -----
>From: "John Barnes" <[EMAIL PROTECTED]>
>Newsgroups: groupstudy.cisco
>Sent: Sunday, September 17, 2000 11:48 PM
>Subject: Re: Help about a technical interview I had PLEASE!
>
>
> > See comments below.
> >
> >
> > --- "David L. Blair" <[EMAIL PROTECTED]> wrote:
> > >
> > > > 1) What is the size of a token ring frame?
> > > > My answer: Token ring has a variable frame size.
> > > > His answer: 3 bytes..
> > > >
> > > > Isn't that the size of the Token frame?
> > >
> > > Yes.
> > >
> > > >
> > > > 2) What the MTU of a token ring frame? (Isn't
> > > this
> > > > about the same question as #1?)
> > > > My answer: slightly larger that 16K (I couldn't
> > > > remember the exact number)
> > > > His answer: about 4470 bytes .
> > >
> > > He is correct.
> >
> > No, he isn't. Token ring has a variable MTU.
>Oops...the maximum is 18k. I'll go with Priscilla's answer over that of Mr.
>Giles :)
> >
> >
> > >
> > > >
> > > > Ahh... what? He claimed I was thinking about
> > > > FDDI.grrrr Ah. Who's thinking about what?
> > > >
> > > > 3) What is the decision making process involved
> > > when a
> > > > packet enters a router? What three criteria are
> > > used
> > > > to make this decision?
> > > > My answer: It depends. Is this the first
> > > > packet with this destination to arrive at this
> > > router?
> > > > What switching mode is the router configured for.
> > >
> > > Most routers actually do not switch that requires a
> > > switching module in the
> > > router. Since routers have to make a routing
> > > decision on a packet, by
> > > default a router reads the whole packet before it
> > > makes a decision that is
> > > why routers forward packets slower than a switch. A
> > > switch is basically a
> > > fixed function bridge that can have one of three
> > > modes: Cut Through, Store
> > > and Forward, or Fragment Free.
> > >
> >
> >
> > Actually, every router does. Unless you disable it
> > with a no ip-route cache on the interface, almost
> > every Cisco router does fast switching by default.
> > This means the first packet is checked against the
> > routing information base, then subsequent packets
> > recieved on the same interface with the same
> > destination are fast switched using the route cache,
> > not process switched. Regardless, the first packet
> > received for a given destination on an interface is
> > ALWAYS process switched.
> >
> >
> > > >
> > > > His answer: Forget about that stuff. how
> > > does
> > > > it determine which route to use.
> > > >
> > > > My answer: longest match in the routing
> > > table
> > > >
> > > > His answer: What if multiple routes exist
> > > in
> > > > the table.
> > > >
> > > > My answer: It depends.
> > > >
> > >
> > >
> > > > Maybe I should have picked up on this stuff
> > > when
> > > > the recruiter asked me with BGP was a DV or LS
> > > based
> > > > routing protocol. My answer. ahh.neither, it's
> > > path
> > > > vector.
> > >
> > > BGP is an External Gateway Protocol which most
> > > closely resembles DV.
> > >
> >
> > BGP is a Path Vector routing protocol, although it
> > more closely resembles a DV, it is not.
> >
> >
> > __________________________________________________
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> >
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>
>**NOTE: New CCNA/CCDA List has been formed. For more information go to
>http://www.groupstudy.com/list/Associates.html
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
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