Cool, thanks for the confirmation and the education.
Funny thing, I'm using your Designing Routing and Switching book as one of
my references.
Thanks again,
Sean C.
CCNP, CCDP, MCSE
""Howard C. Berkowitz"" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> >Hi All,
> >
> >HostA----------Router1-----------Router2-----------HostB
> > Ether Serial Ether
> >
> >If a packet is sent from HostA to HostB and the packet is lost between R1
> >and R2 - who resends?
> >
> >I've seen this question before and thought the generally agreed upon
answer
> >was that Host A would resend with the reason being "The data-link layer
> >protocols in use today on serial lines, including PPP, Frame Relay, and
> >Cisco HDLC, detect errors but are not responsible for error correction or
> >retransmission."
>
> In general, I'd say Host A. The difficulty, however, is that there
> is no absolute rule for what hosts do and what routers do. It's a
> question of the specific protocols in use.
>
> If, for example, the Ethernet between R1 and R2 were running X.25
> (not a common configuration, but specified in ISO 8880), R1 would
> retransmit.
>
> I can come up with even weirder configurations involving multiple
> levels of tunneling, but, if it is an IP environment, hosts are
> architecturally responsible for the reliability of communications. I
> used words very carefully there -- I'm not saying "reliable" but
> simply the appropriate level of reliability. If, for example, the
> hosts are running a UDP-based application such as streaming video, no
> one will retransmit.
>
> Again, the IP architecture assumes the default behavior of
> retransmission, if done at all, is done in hosts. Routers retransmit
> only when they are using data link protocols that specifically
> retransmit (e.g., SDLC and LAP-B), or when they are acting as a host
> (e.g., as a protocol converter or endpoint of a reliable tunnel).
>
> >
> >The reason I post this is I have found a contradictoring document and
wanted
> >some 2nd and 3rd opinions. The document in questions is the cramsession
> >from BrainBuzz.com at the link:
> >
> >http://cramsession.brainbuzz.com/cramsession/cisco/ccie_written/
> >
> >The statement in question is at the top of Page 13. It states the the
> >packet would be resent (actually rebroadcast) from Router B.
> >
> >I'm not using this guide to learn from as much to reinforce what I have
> >learned and this statement is bringing up an old question.
> >
> >Thanks to all who answer,
> >Sean
> >FAQ, list archives, and subscription info:
> >http://www.groupstudy.com/list/cisco.html
> >Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
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