While I wait for someone to clear my messages from the inept filters that
excluded me from participating in discussions today (ARGH), I thought I
would send a few comments about IRDP, which someone was asking about. I'm
going to try to not use any smileys and not include my signature that has a
URL in it and see if that helps. I also promise no profanities or hypertext
code. Oh, I'm just dying to put in a smiley here. No, stop it fingers.
IP workstation-to-router communication in the IP world is absolutely
essential, but surprisingly fragile. One option is the Router Discovery
Protocol (RDP). Request for Comments (RFC) 1256 specifies the RDP extension
to the Internet Control Message Protocol (ICMP).
With RDP, each router on a LAN segment periodically multicasts an ICMP
router advertisement packet from each of its interfaces, announcing the IP
address of that interface. Workstations discover the addresses of their
local routers simply by listening for advertisements, in a similar fashion
to the method AppleTalk workstations use to discover the address of a
router. (The default advertising rate for RDP is once every 7 to 10
minutes, however, which is quite different than AppleTalk, which is once
every 10 seconds).
When a workstation starts up, it can multicast an ICMP router solicitation
packet to ask for immediate advertisements, rather than wait for the next
periodic advertisement to arrive. Although most routers support RDP, few
workstation IP implementations support it, so RDP is not widely used. RDP
is not the default configuration on Cisco routers. If had been the default,
like Proxy ARP is the default, RDP might have caught on.
Priscilla
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=8470&t=8470
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