Thomas Narten wrote:
please review the draft-shen-icmp-routing-inst-00.txt
just submitted, and send any comment you may have.
What scope are these extensions intended to cover? Are they restricted
to being included only in ICMP Time Exceeded messages?
The intention seems to be to supplement the info available for
traceroute. But, traceroute sends UDP messages to an arbitrary
port. I.e., there is no one distinctive "traceroute" messages. Thus,
all time exceeded ICMP messages would presumably include these
extensions. (Or maybe just for UDP messages?)
Not sure I really like augmenting ICMP with more stuff only to benefit
a narrow purpose (e.g., traceroute). Slippery slope here. Where do we
draw the line between what is OK and what is not?
And the specific extensions are of little value to most users. i.e.;
The router MAY include the AS number [3] when sending out the
ICMP messages.
...
I am curious how you concluded that "the specific extensions are of
little value to most users".
In the last ten years or longer, customers/providers had to bend
backward in order to obtain the AS number in debugging network
problems. That's why some vendors query the routing table and then
display the AS number in traceroute. But that information is accurate
only when the full routes are carried.
Both Naiming and I used to work for a large provider. The need for the
AS number in the tracereoute is compelling. Clearly not all extensions
are equal, and some are more useful than others.
-- Enke
The router MAY include the Multi-Topology ID [4, 5] when sending
out the ICMP messages.
...
The router MAY include the Area ID for OSPF [6] when sending
out the ICMP messages.
...
The router MAY include the IS-IS level [7] when sending out the
ICMP messages.
...
The router MAY include the IGRP AS ID or EIGRP AS Number when sending
out the ICMP messages.
...
The router MAY include the virtual router identifier of VRRP [9]
when sending out the ICMP messages.
Thomas
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