If IP route sharing is disabled, the first best route is installed in the hardware table, if multiple best routes are available. Hence the compression algorithm considers the first best route for ECMP (Equal Cost Multi Paths) cases. As shown in the following table, when IP route sharing is disabled, all routes are compressed, except the first one in this case.
Route Manager‘s Table When IP Route Sharing is Disabled
| Prefix | Gateways | Compressed? |
|---|---|---|
| 20.0.0.0/8 | Gw1: 30.1.10.1, Gw2: 50.1.10.1 | NO |
| 20.1.10.0/24 | Gw1: 30.1.10.1 | YES |
| 20.2.10.0/24 | Gw1: 30.1.10.1, Gw2: 60.1.10.1 | YES |
| 20.3.10.0/24 | Gw1: 30.1.10.1, Gw2: 50.1.10.1 | YES |
| 20.4.10.0/24 | Gw1: 30.1.10.1, Gw2: 50.1.10.1 Gw3: 60.1.10.1 | YES |
| 20.1.10.44/32 | Gw1: 30.1.10.1 Gw2: 50.1.10.1 | YES |
HAL(TCAM)/Kernel Routing Table When IP Route Sharing is Disabled
| Prefix | Gateway |
|---|---|
| 20.0.0.8/16 | Gw1: 30.1.10.1, |
Sample output is shown below:
* (debug) # disable iproute sharing * (debug) # show iproute Ori Destination Gateway Mtr Flags VLAN Duration #s Default Route 12.1.10.10 1 UG---S-um--f v1 0d:19h:58m:58s #s Default Route 12.1.10.12 1 UG---S-um--- v1 0d:19h:12m:53s #d 12.1.10.0/24 12.1.10.62 1 U------um--f v1 0d:19h:58m:59s d 16.1.10.0/24 16.1.10.62 1 -------um--- v16 0d:19h:58m:59s #d 22.1.10.0/24 22.1.10.62 1 U------um--f v2 0d:19h:58m:59s #s 33.33.33.0/24 12.1.10.25 1 UG---S-um--f v1 0d:19h:58m:58s #s 55.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #s 55.0.0.0/8 22.1.10.33 1 UG---S-um--- v2 0d:19h:58m:58s #s 55.2.1.1/32 12.1.10.22 1 UG---S-um--f v1 0d:19h:58m:58s #s 55.5.5.1/32 12.1.10.44 1 UG---S-um--f v1 0d:19h:58m:58s #s 66.0.0.0/8 12.1.10.12 1 UG---S-um--f v1 0d:19h:58m:58s #s 66.0.0.0/16 12.1.10.12 1 UG---S-um--c v1 0d:19h:58m:58s #d 70.1.10.0/24 70.1.10.62 1 U------um--f v7 0d:19h:58m:59s #s 78.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #s 79.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #s 79.0.0.0/8 12.1.10.12 1 UG---S-um--- v1 0d:19h:58m:58s #s 80.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #d 80.1.10.0/24 80.1.10.62 1 U------um--f v8 0d:19h:58m:59s #s 81.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #s 81.0.0.0/8 12.1.10.12 1 UG---S-um--- v1 0d:19h:58m:58s #s 81.0.0.0/8 12.1.10.13 1 UG---S-um--- v1 0d:19h:58m:58s #s 82.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #s 83.0.0.0/8 12.1.10.10 1 UG---S-um--c v1 0d:19h:58m:58s #d 91.1.10.0/24 91.1.10.62 1 U------um--f v9 0d:19h:58m:59s #d 92.1.10.0/24 92.1.10.62 1 U------um--f v10 0d:19h:59m:2s #d 93.1.10.0/24 93.1.10.62 1 U------um--f v11 0d:19h:59m:2s Origin(Ori): (b) BlackHole, (be) EBGP, (bg) BGP, (bi) IBGP, (bo) BOOTP (ct) CBT, (d) Direct, (df) DownIF, (dv) DVMRP, (e1) ISISL1Ext (e2) ISISL2Ext, (h) Hardcoded, (i) ICMP, (i1) ISISL1 (i2) ISISL2 (is) ISIS, (mb) MBGP, (mbe) MBGPExt, (mbi) MBGPInter, (mp) MPLS Lsp (mo) MOSPF (o) OSPF, (o1) OSPFExt1, (o2) OSPFExt2 (oa) OSPFIntra, (oe) OSPFAsExt, (or) OSPFInter, (pd) PIM-DM, (ps) PIM-SM (r) RIP, (ra) RtAdvrt, (s) Static, (sv) SLB_VIP, (un) UnKnown (*) Preferred unicast route (@) Preferred multicast route (#) Preferred unicast and multicast route Flags: (B) BlackHole, (D) Dynamic, (G) Gateway, (H) Host Route (L) Matching LDP LSP, (l) Calculated LDP LSP, (m) Multicast (P) LPM-routing, (R) Modified, (S) Static, (s) Static LSP (T) Matching RSVP-TE LSP, (t) Calculated RSVP-TE LSP, (u) Unicast, (U) Up (f) Provided to FIB (c) Compressed Route Mask distribution: 2 default routes 12 routes at length 8 1 routes at length 16 9 routes at length 24 2 routes at length 32 Route Origin distribution: 8 routes from Direct 18 routes from Static Total number of routes = 26 Total number of compressed routes = 8
If the parent node of the LSP route is also an LSP route
If the LSP nexthop of the parent node matches with this node
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