The FF reservation style specifies an explicit list of senders and a distinct bandwidth reservation for each sender. The distinct bandwidth reservation is not shared with other senders, and is identified by an IP address and a local identification number (LSP_ID). Because each sender has its own particular reservation, a unique label and a separate LSP are constructed for each sender-receiver pair.
In RSVP with traffic engineering, each sender and receiver represent a different sender or receiver on a router, not necessarily different end systems. (See Figure 8).
Figure 8 shows a primary and secondary path that share the Fast Ethernet link fe-0/1/2 between R2 and R4. Each path has a separate RSVP session in the FF reservation style. When sessions share a link, the total amount of reserved bandwidth on the shared link is the sum of the reservations for each individual session. If the sum of reservations is larger than the available bandwidth, the LSP cannot be established, as illustrated in the example network in Figure 8.
In the example network in Figure 8, R1 requests a 75-Mbps bandwidth reservation for all configured primary and secondary paths. Therefore, to establish a primary and standby secondary path, a 50-Mbps bandwidth reservation is required. Because the Fast Ethernet link has a total of 100 Mbps of bandwidth available, 75 Mbps of which is reserved for the primary path, leaving 25 Mbps for the standby secondary path, the standby secondary path cannot be established.
Action
For an illustration of this situation, see the output for the following commands:
show configuration protocols mpls (See Sample Output)show rsvp session detail (See Sample Output)show mpls lsp extensive (See Sample Output)
Sample Output
user@R1>show configuration protocols mpls
bandwidth 75m;
label-switched-path lsp1 {
to 192.168.5.1;
primary via-r2;
secondary via-r7 {
standby;
}
}
path via-r7 {
10.0.17.14 strict;
10.0.27.1 strict;
10.0.24.14 strict;
10.0.49.2 strict;
}
path via-r2 {
10.0.12.14 strict;
10.0.24.14 strict;
}
interface fe-0/1/0.0;
interface fe-0/1/1.0;
interface so-0/0/3.0;
What It Means
Sample output from R1 for the show configuration protocols mpls command shows the MPLS configuration that includes a bandwidth of 75 Mbps for all paths, LSP lsp1, a primary path, and a standby secondary path. Both named paths, path via-r7 and path via-r2, specify all transit routers up to the egress. The egress router is not specified. Both paths are strict, indicating that the route taken from one router to the next router is a direct path and cannot include any other routers. All specified addresses are interface addresses, ensuring that the incoming interface is the one specified and enforcing routing on a per-link basis.
From the network topology shown in Figure 8, the link shared by both paths is from R2 to R4, fe-0/1/2, or address 10.0.24.14.
Sample Output
user@R1> show rsvp session detail
Ingress RSVP: 1 sessions
192.168.5.1
From: 192.168.1.1, LSPstate: Up, ActiveRoute: 0
LSPname: lsp1,LSPpath: Primary
Suggested label received: -, Suggested label sent: -
Recovery label received: -, Recovery label sent: 102720
Resv style: 1 FF, Label in: -, Label out: 102720
Time left: -, Since: Fri Jul 21 11:08:12 2006
Tspec: rate 75Mbps size 75Mbps peak Infbps m 20 M 1500
Port number: sender 1 receiver 60165 protocol 0
PATH rcvfrom: localclient
Adspec: sent MTU 1500
Path MTU: received 1500
PATH sentto: 10.0.12.14 (fe-0/1/0.0) 6 pkts
RESV rcvfrom: 10.0.12.14 (fe-0/1/0.0) 6 pkts
Explct route: 10.0.12.14 10.0.24.14 10.0.45.2
Record route: <self> 10.0.12.14 10.0.24.14 10.0.45.2
Total 1 displayed, Up 1, Down 0
[...Output truncated...]
What It Means
The sample output from R1 for the show rsvp session detail command shows that R1 has one ingress RSVP session established in the FF style and associated with the primary path, indicating that the standby secondary path is not established. If the secondary standby path was established, we would expect to see two ingress sessions, one for the primary path and another for the secondary standby path.
Sample Output
user@R1> show mpls lsp extensive
Ingress LSP: 1 sessions
192.168.5.1
From: 192.168.1.1,State: Up, ActiveRoute: 0,LSPname: lsp1
ActivePath: via-r2 (primary)
LoadBalance: Random
Encoding type: Packet, Switching type: Packet, GPID: IPv4
*Primary via-r2 State: Up
Bandwidth: 75Mbps
SmartOptimizeTimer: 180
Computed ERO (S [L] denotes strict [loose] hops): (CSPF metric: 3)
10.0.12.14 S 10.0.24.14 S 10.0.45.2 S
Received RRO (ProtectionFlag 1=Available 2=InUse 4=B/W 8=Node 10=SoftPreempt):
10.0.12.14 10.0.24.14 10.0.45.2
5 Jul 21 11:08:12 Selected as active path
4 Jul 21 11:08:12 Record Route: 10.0.12.14 10.0.24.14 10.0.45.2
3 Jul 21 11:08:12 Up
2 Jul 21 11:08:12 Originate Call
1 Jul 21 11:08:12 CSPF: computation result accepted
Standby via-r7 State: Dn
Bandwidth: 75Mbps
SmartOptimizeTimer: 180
No computed ERO.
Created: Fri Jul 21 11:08:11 2006
Total 1 displayed, Up 1, Down 0
[...Output truncated...]
What It Means
Sample output from R1 for the show mpls lsp extensive command shows that 75 Mbps of bandwidth is allocated for each path. The secondary standby path is down (State: Dn) because there is not enough available bandwidth.