Routing

UBC RIPE Atlas Probe

UBC hosts a RIPE Atlas probe at https://atlas.ripe.net/probes/21001/. It may be possible to use it to trace or ping IP addresses that are generally not possible to ping from eduroam WiFi.

External <-> UBC

ubcvisitor (206.87.130.254/21) -> external

Outbound (To external):

1. 10.43.225.254 (Gateway): Does NAT for ubcvisitor?
2. 10.20.216.30: Common gateway for WiFi?
3. 142.103.204.198: Common router for WiFi that makes routing decisions to various UBC subnets or external router?
4. 137.82.88.125: External outbound that peers with BCNet and has IPv4 full table?
5. 134.87.0.58 (345-ix-cr1-ubcab.vncv1.bc.net)
6. (Hops after BCNet removed for simplicity)

eduroam (206.87.130.254/21) <-> external

Outbound (To external):

1. 206.87.135.254 (Gateway): On-link gateway
2. 10.20.216.30: Common gateway for WiFi?
3. 142.103.204.198: Common router for WiFi that makes routing decisions to various UBC subnets or external router?
4. 137.82.88.125: External outbound that peers with BCNet and has IPv4 full table?
5. 134.87.0.58 (345-ix-cr1-ubcab.vncv1.bc.net): Upstream
6. (Hops after BCNet removed for simplicity)

Selecting a different destination IP will replace the 4th hop above (after leaving UBC 137.82.88.125). This indicates that 137.82.88.125 is peered with BCNet and receives a full IPv4 table that directs routes to diffrerent BCNet transit servers.

Inbound (From external):

1. (Hops prior to BCNet removed for simplicity)
2. 134.87.0.57 (345-ix-ubcab-cr1.vncv1.bc.net): Upstream
3. 137.82.88.122: External inbound that peers with BCNet?
4. 142.103.204.197: Similar to 142.103.204.198, WiFi router, but for inbound?
5. ???: Guess to be 10/8 gateway for WiFi?
6. 206.87.130.254 (eduroam)

pender.students.cs.ubc.ca (198.162.33.17/24) <-> external

Note: this server (pender.students.cs.ubc.ca) has two IP addresses: 198.162.33.17 and 198.162.33.37. We are using former as src IP because it is the default route on this server, although remote.students.cs.ubc.ca resolves to the later IP. Both IPs drop ICMP echo requests after a0-a3.net.ubc.ca.

Outbound (To external):

1. 198.162.33.253 (Gateway, cs-net-33-router2.cs.ubc.ca): On-link gateway?
2. 137.82.73.5: ???
3. 142.103.78.250 (a0-a1.net.ubc.ca): Common router that makes routing decisions?
4. 137.82.88.125: External outbound that peers with BCNet and has IPv4 full table?
5. 134.87.0.58 (345-ix-cr1-ubcab.vncv1.bc.net): Upstream
6. (Hops after BCNet removed for simplicity)

Inbound (From external): Complete inbound impossible because hops after a0-a1.net.ubc.ca are dropped.

1. (Hops prior to BCNet removed for simplicity)
2. 134.87.0.57 (345-ix-ubcab-cr1.vncv1.bc.net): Upstream
3. 137.82.88.122: External inbound that peers with BCNet?
4. 142.103.78.250 (a0-a1.net.ubc.ca): Common router that makes routing decisions?
5. (Hops after a1-a0.net.ubc.ca are dropped)

External -> dsci-100-instructor.stat.ubc.ca (142.103.37.173)

1. (Hops prior to BCNet removed for simplicity)
2. 134.87.0.57 (345-ix-ubcab-cr1.vncv1.bc.net): Upstream
3. 137.82.88.121: External inbound that peers with BCNet?
4. 142.103.78.121: Some dept routers?
5. 137.82.221.70: Some dept routers?
6. ???: Some dept routers?
7. ???: Some dept routers?
8. 142.103.37.253 (gw-37pri.stat.ubc.ca)
9. 142.103.37.173 (dsci-100-instructor.stat.ubc.ca)

eduroam <-> dept servers

pender.students.cs.ubc.ca (198.162.33.17/24) <-> eduroam (206.87.130.254/21)

To eduroam:

1. 198.162.33.253 (Gateway, cs-net-33-router2.cs.ubc.ca): On-link gateway?
2. 137.82.73.5: ???
3. 142.103.78.250 (a0-a1.net.ubc.ca): Common router that makes routing decisions?
4. 142.103.204.197: Similar to 142.103.204.198, WiFi router, but for inbound?
5. 10.45.25.134: Yet-another gateway for WiFi?
6. 206.87.130.254 (eduroam)

From eduroam:

1. 206.87.135.254 (Gateway): On-link gateway
2. 10.20.216.30: Common gateway for WiFi?
3. 142.103.204.198: Common router for WiFi that makes routing decisions to various UBC subnets or external router?
4. 142.103.78.249 (a1-a0.net.ubc.ca)
5. (Hops after a1-a0.net.ubc.ca are dropped)

eduroam (206.87.130.254/21) -> www.cs.ubc.ca (142.103.6.5)

1. 206.87.135.254 (Gateway): On-link gateway
2. 10.20.216.30: Common gateway for WiFi?
3. 142.103.204.198: Common router for WiFi that makes routing decisions to various UBC subnets or external router?
4. 142.103.78.250 (a0-a1.net.ubc.ca): Common router that makes routing decisions?
5. 137.82.73.13
6. 142.103.6.5 (www.cs.ubc.ca)

eduroam (206.87.130.254/21) -> phys119.phas.ubc.ca (142.103.51.11)

1. 206.87.135.254 (Gateway): On-link gateway
2. 10.20.216.30: Common gateway for WiFi?
3. 142.103.204.198: Common router for WiFi that makes routing decisions to various UBC subnets or external router?
4. 142.103.78.2 (l0-a0.net.ubc.ca): Common router that makes routing decisions?
5. 142.103.78.121: Some dept routers?
6. 137.82.221.174: Some dept routers?
7. ???: Some dept routers?
8. ???: Some dept routers?
9. 142.103.51.253: Some dept routers?
10. 142.103.51.11 (phys119.phas.ubc.ca)

eduroam (206.87.130.254/21) -> dsci-100-instructor.stat.ubc.ca (142.103.37.173)

1. 206.87.135.254 (Gateway): On-link gateway
2. 10.20.216.30: Common gateway for WiFi?
3. 142.103.204.198: Common router for WiFi that makes routing decisions to various UBC subnets or external router?
4. 142.103.78.2 (l0-a0.net.ubc.ca): Common router that makes routing decisions?
5. 142.103.78.121: Some dept routers?
6. 137.82.221.70: Some dept routers?
7. ???: Some dept routers?
8. ???: Some dept routers?
9. 142.103.37.253 (gw-37pri.stat.ubc.ca)
10. 142.103.37.173 (dsci-100-instructor.stat.ubc.ca)

We can conclude that:

1. All outbound traffics go through 137.82.88.125, which is peered with BCNet. From BGP.HE.NET, BCNet (AS271) is the only upstream UBC uses.
2. ubcvisitor likely does SNAT on its first hop (direct gateway on-link). Although this can't be seen from the traceroute, I would design in such way if I were the IT.