The BigIP ISP network contains 5 PE LSRs (R1 - R5). BigIP uses OSPF to synchronize...

  

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The BigIP ISP network contains 5 PE LSRs (R1 - R5). BigIP uses OSPF to synchronize global routing tables among these 5 routers. All link bandwidths are 1 Gbps. BigIP has two corporate customers - the Gordon Corporation has 4 customer sites, which are connected to BigIP PE routers R1, R2, R3, R5, respectively, while Blatchley Enterprises has one customer site connected to BigIP PE router R4. R4 redistributes eBGP over OSPF and vice-versa. Each customer site has a Customer Edge (CE) router, which runs eBGP with its directly-connected PE. The 4 Gordon sites are connected together as a single 4-site Virtual Private Network (VPN). BigIP configures layer 3 MPLS VPN service on LSRs R1, R2, R3 and R5 to provide this VPN service to Gordon sites. PHP is enabled. The Blatchley site is not on any VPN. 1. (4 points) How many VRF interfaces are there in the diagram? Tell me the name (router name & interface name) of each router interface on the diagram which is a VRF interface. 2. (10 points) Out of the 5 numbered IP subnets shown in the diagram: a) Which of these subnets will be in the router R3 global routing table? b) Which of these subnets will be in the router R.3 VRF routing table (for the Gordon VPN)? c) Which of these subnets will be in the routing table of the Gordon CE connected to R5? 3. A packet is sent from source IP 40.1.22.9 to destination IP 40.1.21.156. When LSR R3 receives this packet on interface S0/0, it will push two labels (VPN and LDP label) onto the packet and send it out interface S0/2. a) (3 points) Why are 2 labels needed? What is the purpose of each label? b) (3 points) In what table does LSR R3 look up these two label values before forwarding the packet - choose one: (a) VRF routing table, (b) global routing table. (c) VRF CEF table, (d) global CEF table or (e) LFIB table? c) (3 points) When LSR R1 receives this labeled packet from R3, which label will it look up in its LFIB - the VPN label or the LDP label? 5. 6. d) (3 points) How many labels (that is, how many MPLS headers) will be in this packet on the hop from R3 to R1? How many labels (i.e., MPLS headers) will this packet carry on the hop from R1 to R2? e) (4 points) What protocol was used to advertise (distribute) the VPN label value to R3? Which LSR was the source of the packet that advertised this label value? f) (4 points) What protocol was used to advertise (distribute) the LDP label value to R3? Which LSR was the source of the packet that advertised this label value? 4. (4 points) How many iBGP sessions (that is, how many 2-way iBGP TCP connections) are established between BigIP routers to provide this VPN service? (4 points) What is a major difference between ATOM service and VPLS service? Assume that there are two customers - cust-one and cust-two - each has business sites in both New York and LA. Each NY customer site has its own Ethernet attachment circuit (AC) into a single provider edge router, PE-1, in New York and each LA site has its own Ethernet AC into a single provider edge router, PE-2, in LA. The provider uses two Ethernet over MPLS (EoMPLS) pseudowires - one for cust-one and one for cust-two - to pass their Ethernet traffic between PE-1 and PE-2. Each packet carries 2 labels - the VC label and the LDP label. a) (4 points) For packets sent out of PE-1 going to PE-2, can the LDP Label in cust-one packets have the same value as the LDP Label in cust-two packets? Why or why not? (4 points) For packets sent out of PE-1 going to PE-2, can the VC Label in cust-one packets have the same value as the VC Label in cust-two packets? Why or why not? b) Subnet S00 CE $0/0 Gordon Corp. 40.1.23.0/24 S0/1 $0/2 R5 Gordon Corp. 40.1.21.0/24 Subne S010 CE S0/1 SO/2 $0/0 Subnet so/d R4 Blatchley Ent. 50.1.0.0/16 $0/0 R2 CE $0/2 S0/1 $0/1 $0/1 R3 $0/0 $0/2 50/2 R1 soro Gordon Corp. 40.1.22.0/24 ibnet $0/0 CE $040 Gordon Corp. 40.1.20.0/24 abnet CE The BigIP ISP network contains 5 PE LSRs (R1 - R5). BigIP uses OSPF to synchronize global routing tables among these 5 routers. All link bandwidths are 1 Gbps. BigIP has two corporate customers - the Gordon Corporation has 4 customer sites, which are connected to BigIP PE routers R1, R2, R3, R5, respectively, while Blatchley Enterprises has one customer site connected to BigIP PE router R4. R4 redistributes eBGP over OSPF and vice-versa. Each customer site has a Customer Edge (CE) router, which runs eBGP with its directly-connected PE. The 4 Gordon sites are connected together as a single 4-site Virtual Private Network (VPN). BigIP configures layer 3 MPLS VPN service on LSRs R1, R2, R3 and R5 to provide this VPN service to Gordon sites. PHP is enabled. The Blatchley site is not on any VPN. 1. (4 points) How many VRF interfaces are there in the diagram? Tell me the name (router name & interface name) of each router interface on the diagram which is a VRF interface. 2. (10 points) Out of the 5 numbered IP subnets shown in the diagram: a) Which of these subnets will be in the router R3 global routing table? b) Which of these subnets will be in the router R.3 VRF routing table (for the Gordon VPN)? c) Which of these subnets will be in the routing table of the Gordon CE connected to R5? 3. A packet is sent from source IP 40.1.22.9 to destination IP 40.1.21.156. When LSR R3 receives this packet on interface S0/0, it will push two labels (VPN and LDP label) onto the packet and send it out interface S0/2. a) (3 points) Why are 2 labels needed? What is the purpose of each label? b) (3 points) In what table does LSR R3 look up these two label values before forwarding the packet - choose one: (a) VRF routing table, (b) global routing table. (c) VRF CEF table, (d) global CEF table or (e) LFIB table? c) (3 points) When LSR R1 receives this labeled packet from R3, which label will it look up in its LFIB - the VPN label or the LDP label? 5. 6. d) (3 points) How many labels (that is, how many MPLS headers) will be in this packet on the hop from R3 to R1? How many labels (i.e., MPLS headers) will this packet carry on the hop from R1 to R2? e) (4 points) What protocol was used to advertise (distribute) the VPN label value to R3? Which LSR was the source of the packet that advertised this label value? f) (4 points) What protocol was used to advertise (distribute) the LDP label value to R3? Which LSR was the source of the packet that advertised this label value? 4. (4 points) How many iBGP sessions (that is, how many 2-way iBGP TCP connections) are established between BigIP routers to provide this VPN service? (4 points) What is a major difference between ATOM service and VPLS service? Assume that there are two customers - cust-one and cust-two - each has business sites in both New York and LA. Each NY customer site has its own Ethernet attachment circuit (AC) into a single provider edge router, PE-1, in New York and each LA site has its own Ethernet AC into a single provider edge router, PE-2, in LA. The provider uses two Ethernet over MPLS (EoMPLS) pseudowires - one for cust-one and one for cust-two - to pass their Ethernet traffic between PE-1 and PE-2. Each packet carries 2 labels - the VC label and the LDP label. a) (4 points) For packets sent out of PE-1 going to PE-2, can the LDP Label in cust-one packets have the same value as the LDP Label in cust-two packets? Why or why not? (4 points) For packets sent out of PE-1 going to PE-2, can the VC Label in cust-one packets have the same value as the VC Label in cust-two packets? Why or why not? b) Subnet S00 CE $0/0 Gordon Corp. 40.1.23.0/24 S0/1 $0/2 R5 Gordon Corp. 40.1.21.0/24 Subne S010 CE S0/1 SO/2 $0/0 Subnet so/d R4 Blatchley Ent. 50.1.0.0/16 $0/0 R2 CE $0/2 S0/1 $0/1 $0/1 R3 $0/0 $0/2 50/2 R1 soro Gordon Corp. 40.1.22.0/24 ibnet $0/0 CE $040 Gordon Corp. 40.1.20.0/24 abnet CE

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1 There are 8 VRF interfaces in the diagram R1 S01 S02 S03 S04 R2 S01 S02 S03 S04 R3 S01 S02 S03 S04 R4 S01 S02 R5 S01 S02 2 a The following subnets w... View the full answer