Traceroute question

CheesyBread

Guys, what does this mean when it shows the !A * !A ? I'm trying to traceroute an MPLS link and this is all I get.



AR#traceroute 192.168.105.10

Type escape sequence to abort.
Tracing the route to 192.168.105.10

1 192.168.105.10 !A * !A
AR#

MrBrian

Ahh, I had just read about this in the Cisco white pages recently and your question reminded me of it.. I kind of skipped over it the first time, but now rereading it, I feel like I learned something new, thanks! Lol.

Anyways, it looks like an A in the traceroute output means "Administratively prohibited (example, access list)." So there you have it. Not sure why you get a combo of ! and A though, that'll take more pondering. It's got me curious though.. The ping program outputs a ! for a echo reply, but I didn't think traceroute output that.. I know that traceroute sends out UDP datagrams to random, unreachable ports, so the program knows when it hit the destination upon receiving a destination port unreachable. Also, each hop is noted by receiving an icmp time exceeded error because of the TTL expiring. So I'm trying to imagine the access-list.. If you find it I wanna see it lol.

Here's the link to the Cisco documentation.. it covers ping and traceroute. Just scroll way down for traceroute info and you'll see the table with the meaning of each possible character output.

Understanding the Ping and Traceroute Commands - Cisco Systems

MrBrian

Hmm.. there's also some documentation on using traceroute in an MPLS network, which may be of more value to you.

The Traceroute Command in MPLS  [MPLS] - Cisco Systems

CheesyBread

I had reviewed the MPLS traceroute section extensively since there is a confirmed "traceroute mpls ipv4 A.B.C.D/32" command and I wanted to make sure I didn't over look that.

I believe I had a wrong IP address, I think. I checked the MPLS section in my Sprint Compass account and found a different IP for our alaska site. I did a traceroute on that :

AR#traceroute 172.30.0.9

Type escape sequence to abort.
Tracing the route to 172.30.0.9

1 172.30.0.1 4 msec 4 msec 4 msec
2 172.30.0.25 [MPLS: Label 8419 Exp 0] 24 msec 28 msec 32 msec
3 172.30.0.26 108 msec 112 msec 108 msec
4 172.21.48.245 108 msec 116 msec 116 msec
5 172.21.48.250 108 msec 112 msec 108 msec
6 172.30.0.9 112 msec * 108 msec
AR#

I'm really struggling here. Our only WAN guy is like on the brink of suicide because he's so busy, he can't even really sleep and he's trying to give me a crash course in MPLS and WAN routing so I can take over as the engineer for that stuff.

Only thing is, I'm barely CCNA level and I'm reading the 2010 Cisco Press MPLS fundamentals AND a cisco press ROUTE book which are both way over my head.

I have the next 10 days off as "vacation" but they want me to read both these books by the time I come back.

MrBrian

Your guys' team must be pretty small eh? Well hey, soak it up man. I think it sounds kind of awesome lol. The fact that they're relying on you to be responsible for something you admittedly don't really know. You'll learn a ton from it probably. Only thing that's tough is they're only giving you 10 days to try and learn it!

It does sound pressuring though, I will admit. Just do your best to soak it up and stay positive. I think this whole experience will only make you a better engineer moving forward.

drkat

Most hops in a trace through MPLS will time out - a lot of routers do not respond.

My main expertise is WAN stuff so if you have any questions feel free to PM me.

What we're really concerned with the trace is the last hop if it completes or where it starts timing out

also with determining "lag" we're looking at the time on the last hop not the intermediate ones since routers are design to route traffic and return icmp requests last.