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traceroute question

I was doing a traceroute and i see down near the bottom a 10.x.x.x address. I may be asking a stupid question but arent these not private addresses? how come i see this then? look down to number 15-16

root@devsrv1 root]# traceroute 200.21.18.197 traceroute to 200.21.18.197 (200.21.18.197), 30 hops max, 38 byte packets

2 hse-sherbrooke-ppp98688.qc.sympatico.ca (64.230.222.81) 7.350 ms 7.079 ms 6.863 ms 3 core3-toronto63-gigabite4-0.in.bellnexxia.net (206.108.107.169) 7.223 ms 7.525 ms 7.110 ms 4 bx1-toronto63-pos1-0.in.bellnexxia.net (64.230.242.114) 7.147 ms 6.711 ms 7.349 ms 5 if-7-0.core2.ttt-scarborough.teleglobe.net (207.45.198.1) 7.626 ms 7.508 ms 7.611 ms 6 if-3-0.core2.cqw-chicago.teleglobe.net (207.45.222.182) 19.409 ms 19.383 ms 37.419 ms MPLS Label=394 CoS=3 TTL=1 S=0 7 if-7-0.core2.ct8-chicago.teleglobe.net (66.110.14.165) 18.768 ms 21.994 ms 18.434 ms 8 0.so-1-2-3.BR6.CHI2.ALTER.NET (204.255.169.17) 20.008 ms 20.097 ms 19.445 ms 9 0.so-5-3-0.xl1.chi2.alter.net (152.63.64.50) 19.927 ms 19.582 ms 19.411 ms 10 0.so-0-0-0.tl1.chi2.alter.net (152.63.68.82) 19.720 ms 21.642 ms 19.653 ms 11 0.so-3-0-0.tl1.atl5.alter.net (152.63.38.62) 44.102 ms 43.798 ms 43.556 ms 12 0.so-7-0-0.xl1.mia4.alter.net (152.63.86.189) 59.312 ms 58.963 ms 58.999 ms 13 pos6-0.gw4.mia4.alter.net (152.63.82.141) 58.947 ms 59.700 ms 58.752 ms 14 telecomnetco-gw.customer.alter.net (157.130.75.250) 120.253 ms 120.492 ms 119.772 ms 15 10.0.16.69 (10.0.16.69) 120.484 ms 120.558 ms 123.883 ms 16 10.0.16.2 (10.0.16.2) 177.173 ms 120.365 ms 119.958 ms 17 200.21.211.106 (200.21.211.106) 368.640 ms 341.883 ms 407.430 ms 18 200.21.18.197 (200.21.18.197) 403.910 ms 400.602 ms 451.870 ms [root@devsrv1 root]#
Reply to
Steven Kalcevich
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They are private addresses, but since they are used on links between routers, it is perfectly ok to use them. They aren't destination addresses.

Scott

Reply to
thrill5

Hi there,

What type of routes would these be in? Within a pop? I would like to know why someone would use private addresses. is this common practice to do? Is it just to preserve ip addresses? Is there a security reason behind this? Say for instance if someone wanted to DOS this router

10.0.16.69 it would not be possible unless you were directly connected to it as its a private address.

thrill5 wrote:

Reply to
Steven Kalcevich

It looks like the customer is using them on their own internal links. telecomnetco-gw.customer.alter.net is the router at the customer end of the link to the ISP. Everything after that is the customer's network.

Reply to
Barry Margolin

hey,

I need to understand this. Why would an ISP (200.21.18.197)

formatting link
who has a US link with Alternet (157.130.75.250) have a link to cuba
formatting link
use internal addresses. They have 2 class c's that I know from traceroute. Is this a common pratice or an error? Thank you in advance oh ip addressing guru.

Barry Margol> >

Reply to
Steven Kalcevich

The question has already been answered. It is common practice to use RFC

1918 address space within a network and as they are not source or destination addresses they do not need to be 'internet routeable'.
Reply to
Tom

To add to this, it helps to understand the interoperation of BGP and IGP. Whoever owns these links is routing your icmp packets there via their IGP, not BGP.

The 10.x.x.x networks will never appear in the global routing table since: a) they are not ingress or egress point to a BGP autonomous system b) they will never be the destination point for any internet traffic (being in all likelihood /30 point to point links) c) they will get filtered anyway being private addressing

Reply to
Ben

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