"Marco Rodrigues" <[EMAIL PROTECTED]> wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Hello Group,
>
> I dont' know if anyone found this yet, but I couldn't find an
> errata on the ciscopress homepage so here it goes. On Pg .100 it states
> that a VLAN ID header is 10 bits long in the first 26 bytes of the ISL
> encapulation. But later in Figure 3-7 it says the VLAN ID field is 15
> bits. Can someone clarify this for me?
I don't have the book handy, so I can't cover this one. I will say that you
will find many more errors in this book. It is a good reference, and will
get you though the test, but if ever a book screamed for an errata, its this
one. There were a couple of others pointed out by others, so check the
groupstudy archives. One bad one is in the exercises for multicast IP-to-MAC
translation.
> Another issue is on Pg 104 is says original ethernet frames can't exceed
> 1518 bytes. But they state that if using 802.1q the frame becomes 1522
> bytes long. I thought 802.1q inserts it's information into the exsisting
> ethernet frame and ISL encapulates it making the size of the frame 1522
> bytes. Can someone also clarify this of me?
IIRC, the frame, with the 802.1q tag inserted, is still an ethernet frame,
and thus you could get notification on the switch of oversized frames if it
exceeds 1518 bytes. However, with the ISL encapsulation, the frame is no
longer an ethernet frame, it is an ISL frame, so the size limitation doesn't
apply.
---JRE---
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