Fix interop issue for EVPN w/ MPLS in GRE encapsulation

Current version of EVPN overlay draft says to use MPLSoGRE codepoint,
whereas Contrail uses GRE. This results in interop issues with other
implementations.

The justification for definining a new code point for MPLSoGRE is not
clear. In the intrest of improving interoperability, advertise both GRE
and MPLSoGRE for EVPN routes and map both GRE and MPLSoGRE to the same
string value when advertising routes via xmpp.

Change-Id: I6d01053de225c8058756f9d76682164b6499352e
Closes-Bug: 1588554

src/bgp/bgp_xmpp_channel.cc

@@ -1614,9 +1614,19 @@ bool BgpXmppChannel::ProcessEnetItem(string vrf_name,
                 if (first_nh) {
                     ext.communities.push_back(
                         tun_encap.GetExtCommunityValue());
+                    if (tun_encap.tunnel_encap() == TunnelEncapType::GRE) {
+                        TunnelEncap alt_tun_encap(TunnelEncapType::MPLS_O_GRE);
+                        ext.communities.push_back(
+                            alt_tun_encap.GetExtCommunityValue());
+                    }
                 }
                 nexthop.tunnel_encapsulations_.push_back(
                     tun_encap.GetExtCommunity());
+                if (tun_encap.tunnel_encap() == TunnelEncapType::GRE) {
+                    TunnelEncap alt_tun_encap(TunnelEncapType::MPLS_O_GRE);
+                    nexthop.tunnel_encapsulations_.push_back(
+                        alt_tun_encap.GetExtCommunity());
+                }
             }
 
             // Mark the path as infeasible if all tunnel encaps published

src/bgp/tunnel_encap/test/tunnel_encap_test.cc

@@ -13,7 +13,7 @@ class TunnelEncapTest : public ::testing::Test {
 
 TEST_F(TunnelEncapTest, String_1) {
     TunnelEncap tunnel_encap("gre");
-    EXPECT_EQ(TunnelEncapType::MPLS_O_GRE, tunnel_encap.tunnel_encap());
+    EXPECT_EQ(TunnelEncapType::GRE, tunnel_encap.tunnel_encap());
     EXPECT_EQ("encapsulation:gre", tunnel_encap.ToString());
     EXPECT_EQ("gre", tunnel_encap.ToXmppString());
 }
@@ -74,10 +74,17 @@ TEST_F(TunnelEncapTest, String_7) {
     EXPECT_EQ("vxlan-gpe", tunnel_encap.ToXmppString());
 }
 
-TEST_F(TunnelEncapTest, EncapType_1) {
+TEST_F(TunnelEncapTest, EncapType_1a) {
+    TunnelEncap tunnel_encap(TunnelEncapType::GRE);
+    EXPECT_EQ(TunnelEncapType::GRE, tunnel_encap.tunnel_encap());
+    EXPECT_EQ("encapsulation:gre", tunnel_encap.ToString());
+    EXPECT_EQ("gre", tunnel_encap.ToXmppString());
+}
+
+TEST_F(TunnelEncapTest, EncapType_1b) {
     TunnelEncap tunnel_encap(TunnelEncapType::MPLS_O_GRE);
     EXPECT_EQ(TunnelEncapType::MPLS_O_GRE, tunnel_encap.tunnel_encap());
-    EXPECT_EQ("encapsulation:gre", tunnel_encap.ToString());
+    EXPECT_EQ("encapsulation:mpls-o-gre", tunnel_encap.ToString());
     EXPECT_EQ("gre", tunnel_encap.ToXmppString());
 }
 
@@ -136,15 +143,24 @@ TEST_F(TunnelEncapTest, EncapType_7) {
     EXPECT_EQ("vxlan-gpe", tunnel_encap.ToXmppString());
 }
 
-TEST_F(TunnelEncapTest, ByteArray_1) {
+TEST_F(TunnelEncapTest, ByteArray_1a) {
     TunnelEncap::bytes_type data =
         { { 0x03, 0x0C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02 } };
     TunnelEncap tunnel_encap(data);
-    EXPECT_EQ(TunnelEncapType::MPLS_O_GRE, tunnel_encap.tunnel_encap());
+    EXPECT_EQ(TunnelEncapType::GRE, tunnel_encap.tunnel_encap());
     EXPECT_EQ("encapsulation:gre", tunnel_encap.ToString());
     EXPECT_EQ("gre", tunnel_encap.ToXmppString());
 }
 
+TEST_F(TunnelEncapTest, ByteArray_1b) {
+    TunnelEncap::bytes_type data =
+        { { 0x03, 0x0C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0B } };
+    TunnelEncap tunnel_encap(data);
+    EXPECT_EQ(TunnelEncapType::MPLS_O_GRE, tunnel_encap.tunnel_encap());
+    EXPECT_EQ("encapsulation:mpls-o-gre", tunnel_encap.ToString());
+    EXPECT_EQ("gre", tunnel_encap.ToXmppString());
+}
+
 TEST_F(TunnelEncapTest, ByteArray_2a) {
     TunnelEncap::bytes_type data =
         { { 0x03, 0x0C, 0x00, 0x00, 0x00, 0x00, 0x00, 0x0d } };

src/net/tunnel_encap_type.cc

@@ -15,7 +15,7 @@ TunnelEncapType::TunnelEncapType() {
 static const map<string, TunnelEncapType::Encap>
     fromString = boost::assign::map_list_of
         ("unspecified", TunnelEncapType::UNSPEC) 
-        ("gre", TunnelEncapType::MPLS_O_GRE) 
+        ("gre", TunnelEncapType::GRE)
         ("vxlan", TunnelEncapType::VXLAN)
         ("nvgre", TunnelEncapType::NVGRE)
         ("mpls", TunnelEncapType::MPLS)
@@ -27,10 +27,11 @@ static const map<string, TunnelEncapType::Encap>
 static const map<TunnelEncapType::Encap, string>
     toString = boost::assign::map_list_of
         (TunnelEncapType::UNSPEC, "unspecified")
-        (TunnelEncapType::MPLS_O_GRE, "gre")
+        (TunnelEncapType::GRE, "gre")
         (TunnelEncapType::VXLAN, "vxlan")
         (TunnelEncapType::NVGRE, "nvgre")
         (TunnelEncapType::MPLS, "mpls")
+        (TunnelEncapType::MPLS_O_GRE, "mpls-o-gre")
         (TunnelEncapType::VXLAN_GPE, "vxlan-gpe")
         (TunnelEncapType::MPLS_O_UDP, "udp")
         (TunnelEncapType::MPLS_O_UDP_CONTRAIL, "udp-contrail")
@@ -39,10 +40,11 @@ static const map<TunnelEncapType::Encap, string>
 static const map<TunnelEncapType::Encap, string>
     toXmppString = boost::assign::map_list_of
         (TunnelEncapType::UNSPEC, "unspecified")
-        (TunnelEncapType::MPLS_O_GRE, "gre")
+        (TunnelEncapType::GRE, "gre")
         (TunnelEncapType::VXLAN, "vxlan")
         (TunnelEncapType::NVGRE, "nvgre")
         (TunnelEncapType::MPLS, "mpls")
+        (TunnelEncapType::MPLS_O_GRE, "gre")
         (TunnelEncapType::VXLAN_GPE, "vxlan-gpe")
         (TunnelEncapType::MPLS_O_UDP, "udp")
         (TunnelEncapType::MPLS_O_UDP_CONTRAIL, "udp")

src/net/tunnel_encap_type.h

@@ -12,10 +12,11 @@ class TunnelEncapType {
 public:
     enum Encap {
         UNSPEC = 0,
-        MPLS_O_GRE = 2,
+        GRE = 2,
         VXLAN = 8,
         NVGRE = 9,
         MPLS = 10,
+        MPLS_O_GRE = 11,
         VXLAN_GPE = 12,
         MPLS_O_UDP = 13,
         MPLS_O_UDP_CONTRAIL = 37001,